AES Meeting Reno 2015,   AES Abstracts only of Presentations and Posters in Chronological Order (posters in numeric order) from ASIH website.

 

0613 Plenary Session, Carson 1, 2 & 3, Thursday 16 July 2015

Jennifer Wyffels

South-East Zoo Alliance for Reproduction and Conservation, Yulee, FL, USA

 

The Changing Face or AES

 

There has been a steady demographic shift occurring in life sciences over the last 30 years, so maybe it’s not so unexpected to see it in the field of elasmobranch science as well. While all fields of science have historically been largely male-dominated, there are now far more women training in biological fields than men; however, the proportion of women entering and remaining within professional careers is still proportionally behind that of males. This trend is particularly true for women and underrepresented groups in AES. Not unlike other fields in the life sciences, pioneers like Eugenie Clark, one of the first women to establish herself as force among elasmobranch scientists in the 1960s, led the way for the next generation of female scientists. Despite increasing numbers of female student members, the number of women remaining in the society as professional members has not increased proportionally. Male AES members have served as president for 26 out of the 30 year history of the society and only two women have been elected as President of AES, the first being Merry Camhi in 2002. There has been a growing number of women serving important leadership roles in AES, particularly over the last 10 years, which is needed to support the needs of our changing society. However, there is also a need to further enrich our ranks with greater diversity.

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AES Conservation & Management/AES Ichthyology, Carson 2, Thursday 16 July 2015 Afternoon

 

0469 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Heather Brekke 2, Nicholas Dulvy 1

1 Simon Fraser University, Vancouver, British Columbia, Canada, 2 Royal Roads University, Victoria, British Columbia, Canada

 

Does it Matter How Many Sharks are Killed Each Year?

 

The number of elasmobranchs killed each year has become a key communication message used to raise public awareness of the plight of sharks, skates, and rays. The total number killed alone may divert attention from conservation success and the true problems, priorities, and actions. We illustrate this with an analysis of extent and pattern of catches of elasmobranchs within Canadian Pacific commercial fisheries over the past 30 years (1980 1980–2013). In Canada, few elasmobranchs are subject to directed commercial fisheries, but some are incidentally caught in fisheries targeting teleosts. A total of 208,642 tonnes of elasmobranchs was recorded in Canadian Pacific waters over the thirty-year period, with most (93%) of weight comprised of the commercially valued elasmobranchs: Spotted Spiny Dogfish (Squalus suckleyi), Big Skate (Raja binoculata), and Longnose Skate (Raja rhina). Most (three-quarters) of the catch was retained and catch retention has changed little over the last 30 years. Overall, on average, nearly two million sharks, skates, and rays have been killed each year and there has been an 80% decline in catch over the last decade. While such statistics could be used to support what Hilborn has called the “litany of decline”, it seems instead that almost all of the recent catch has been sustainable and taken within scientifically set catch limits. Furthermore, the steep decline in catch is more likely to reflect a combination of declining market demand and improved management resulting in the emergence of sustainable elasmobranch fisheries.

 

0529 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Rachel H L Walls, Nicholas K Dulvy

Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada

 

A Tale of Two Seas: The Contrasting Status of Europe’s Elasmobranchs

 

The International Union for Conservation of Nature’s (IUCN) Red List Assessments provide the motivation and foundation for global and regional conservation and fisheries management efforts. Some of the earliest assessments were done in Europe, which led to improved fisheries management measures specific to elasmobranch protection in the Northeast Atlantic. Conversely in the Mediterranean Sea, there has been little scientific or management progress. The IUCN Shark Specialist Group recently reassessed all elasmobranchs in European waters, which allows us to review status changes since 2005 for both the Northeast Atlantic and Mediterranean regions. Our comparison revealed striking differences in the overall status of elasmobranchs since the previous assessments and between regions. While the status of elasmobranchs in the Northeast Atlantic has improved, the Mediterranean status has actually worsened. Approximately 35% of Northeast Atlantic elasmobranchs are considered “safe” compared to only 10% of Mediterranean species. Similarly, 31% of Northeast Atlantic species are threatened with an elevated risk of extinction, compared to almost 50% in the Mediterranean: the highest proportion of threatened species in any region globally. It is likely that the lack of appropriate management measures implemented in the Mediterranean specific to elasmobranchs since the previous Red List assessment is the primary reason for these differences, and this will be explored in greater detail.

 

0554 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Lindsay Davidson, Nicholas Dulvy

Simon Fraser University, Burnaby, Canada

 

Conservation Priorities and Political Responsibilities for Chondrichthyans

 

Global areas with concentrations of biodiversity (hotspots) are often prioritized for conservation and management action. The first hotspot analysis found that 1.5% of the earth's land surface area contained almost half of the world's threatened endemic plants and 30% of threatened vertebrates. The term hotspot has heretofore become a blanket term for finding concentrations of biodiversity using a variety of measurements. For example, the majority of marine analyses have described hotspots based on species richness patterns. Species richness patterns, however, are driven by common species. Therefore basing conservation and management actions on species richness patterns would not protect the most rare or vulnerable species. Here, we use a systematic conservation planning approach to determine the location of global marine hotspots as originally defined by Myers (2000). We define hotspots as global marine areas with concentrations of threatened, endemic chondrichthyans. We found the highest counts of threatened endemics in the national marine waters of, in descending order, Brazil, Taiwan, Uruguay, Argentina, and South Africa. Just over half of the 13 countries with the greatest number of threatened endemics in their national waters have a National Plan of Action (NPOA) for Sharks or finning regulation in place. Only one of the countries, Australia, has a NPOA that meets >65% of the objectives of sustainable fishing. This information can be used to inform the use of limited resources for the conservation of marine threatened species.

 

 

0487 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Sonja Fordham

Shark Advocates International, Washington, DC, USA

 

Spotlight on the Small and Flat: Conservation Status Updates for Select U.S. Atlantic Dogfish, Skates, and Rays

 

While large sharks continue to be a popular focus for conservation attention, smaller, flatter species actually hold the national titles for elasmobranch depletion, recovery, and landings, as well as most and least protected species. As the most commercially important U.S. shark, the spiny dogfish (Squalus acanthias) has been to driven to depletion and back, regulated through quotas that once severely restricted fishing yet now grossly exceed demand. Lagging more than a decade behind in basic assessment and management is the similarly sized Atlantic smoothhound or “smooth dogfish” (Mustelus canis), which feeds poorly understood markets and is the nation’s sole subject of the world’s weakest ban on shark “finning.” A complex of Northwest Atlantic skates (Family Rajidae), used for food and bait, supports the country’s largest elasmobranch fishery, yet the American public’s concern for the overfished species is outweighed by growing appreciation for eating skate wing, thereby allowing for less than rigorous recovery actions. Despite the now notorious “Save the Bay, Eat a Ray” industry campaign, Americans appear more interested in appreciating cownose rays (Rhinoptera bonasus) in touch tanks than on their plates. Still, this exceptionally vulnerable, un- assessed species continues to be taken without limit as bycatch and in tournaments. The focus for ensuring the recovery of Florida’s Endangered Smalltooth Sawfish (Pristis pectinata) has shifted from securing legal safeguards to restoring adequate funding for implementing the recovery plan, particularly programs to prevent mishandling. Following the latest conservation status updates, recommendations for improvement will be offered.

 

0539 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Dewayne Fox 1, Bradley Wetherbee 2, Symone Johnson1, James Kilfoil 1

1 Delaware State University, Dover, DE, USA, 2 University of Rhode Island, Kingston, RI, USA

 

Development of a Multifaceted Conservation Plan for Sand Tigers (Carcharias taurus) in the Delaware Bay and Nearshore Coastal Waters

 

Due to their large size, feeding habits, abundance, and prolonged periods of occurrence, Sand Tigers (Carcharias taurus) serve as apex predators for the Delaware Bay and much of the surrounding nearshore coastal waters. Likely a result of their restricted summer movements and overlap with humans, they unfortunately suffer the consequences of intentional and accidental takes in fisheries. Most problematic is the recently developed and apparently increasing recreational sector targeting this prohibited species. Adding to our concerns is the fact that the fishery has increased in size and popularity after Sand Tigers were listed as a Species of Concern by NOAA-NMFS. Facing a growing problem, the State of Delaware implemented regulatory changes in 2011 in an effort to increase survival of recreationally landed Sand Tigers. While these changes have likely led to reductions in angling pressure, a more unified approach is required to conserve and recover this species. Our plan includes enhanced protection of core Sand Tiger habitats, working with anglers to change practices and/or implement use of conservation engineering approaches, as well changes in cooperative tagging programs and scientific/aquaria collections. While the State of Delaware has taken large steps to educate the public on the need for improved angling practices, the lack of higher level support cannot help but undermine the state's efforts. Ultimately, to be successful and applicable to the US northwest Atlantic Sand Tiger population as a whole, a number of state and federal agencies, as well as local stakeholders must cooperate.

 

 

0071 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Simon Dedman 1, Rick Officer 1, Deirdre Brophy 1, Maurice Clarke 2, David Reid 2

 

1 Galway-Mayo Institute of Technology, Galway, Co. Galway, Ireland, 2 Marine Institute, Rinville, Co. Galway, Ireland

 

Modelling Abundance Hotspots for Data-poor Irish Sea Rays

 

Skates and rays represent one of the most vulnerable components of the fish community in temperate demersal fisheries such as the Irish Sea. They also tend to be data poor in comparison to commercially exploited teleost fish. Spatial management has been suggested as an important tool in protecting these species, but requires an understanding of the abundance distribution, and its relationship with the environment at both adult and juvenile life history stages. In this analysis, delta log-normal boosted regression tree models were used with bottom trawl survey data to derive rays' spatial abundance, and environmental links. The modelling approach allowed the development of detailed predictive maps of abundance of four common and rare skate and ray species implicated in the fishery: thornback, spotted, cuckoo and blonde rays. The distributions were driven by a general preference for sand and courser substrates, higher salinities, temperatures and currents speeds. The abundance distribution maps were examined together with maps of skate and ray commercial landings, suggesting that the main hotspots for the species were away from the main commercial fishing areas. The maps were also compared to potential MPAs proposed for wider ecosystem protection, and the main hotspots were well covered by the proposed MPAs. This combination of the main abundance hotspots in areas of low fishing, and wider potential ecosystem protection, suggests good potential for spatial management measures to protect these species in the Irish Sea.

 

0392 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Matthew Ajemian 1, Philip Jose 1, John Froeschke 2, Gregory Stunz 1

1 Harte Research Institute for Gulf of Mexico Studies, Texas A&M University-Corpus Christi, Corpus Christi, TX, USA, 2 Gulf of Mexico Fishery Management Council, Tampa, FL, USA

 

Trends and Characterization of the Land-based Recreational Shark Fishery off Texas

 

Most analyses of shark population trends use seasonally-limited fishery-independent data that generally neglect important nearshore coastal habitats (i.e.,<20m bottom depth). The Texas coast supports one of the largest year-round, land-based recreational shark fisheries in the United States. However, no studies have characterized the catch composition and overall trends in this fishery despite its beginnings several decades ago. We used fishery-dependent data from two distinct periods (historic = 1973-1986, and modern = 2008-2014) to assess the status of the nearshore shark community off Texas. Monthly catch records from both data sets were examined using multivariate techniques to examine seasonality in shark assemblages as well as potential shifts in catch composition over time. These fishery-dependent data revealed relatively distinct assemblages by season (ANOSIM Global R = 0.159; P = 0.0001) and period (ANOSIM Global R = 0.222; P = 0.0001). Similarity Percentange analysis showed a general shift in shark community assemblage from larger to smaller species. Most notably, Bull Shark (Carcharhinus leucas) dominance decreased over time while Blacktip Shark (Carcharhinus limbatus) contribution increased. Our analyses also identified a large decrease in mean total length (TL) of Bull Sharks from 232.8 cm to 175.1 cm and a modest increase in Blacktip Shark size from 125.1 cm to 127.9 cm TL. These findings document a significant change in the size and composition of Texas’ nearshore shark community potentially driven by overfishing and removal of large (>2 m) sharks. Future management decisions should account for these removals as stocks are rebuilt to historical levels.

 

0575 AES Conservation & Management, Carson 2, Thursday 16 July 2015

Bradley Wetherbee 1, Michael Byrne 5, Jeremy Vaudo 2, Guy Harvey 3, Mahmood Shivji 4

1University of Rhode Island, Kingston, RI, USA, 2 Guy Harvey Research Institute, Ft L auderdale, FL, USA, 3 Guy Harvey Ocean Foundation, Ft Lauderdale, FL, USA, 4 Save Our Seas Foundation Shark Center, Ft Lauderdale, FL, USA, 5Warnell School of Forestry and Natural Resources University of Georgia, Athens, GA, USA

 

Orientation of Mako Sharks (Isurus oxyrinchus) to Environmental Conditions in the Open Ocean

 

Mako sharks (Isurus oxyrinchus) are frequently captured in long line fisheries and are heavily targeted by recreational anglers in many parts of the world. Given the fishing pressure on mako shark populations there is a great deal of interest in management of their stocks. However, information about movements and migrations of mako sharks that would enable comprehensive understanding of interactions with fisheries and delineation of distribution patterns in waters under the jurisdiction of numerous countries is sparse. We tagged 45 mako sharks with satellite transmitters and tracked their movements over the span of several years. A state space model was used to construct continuous tracks for sharks and to categorize their locations into two behavioral states – searching and transiting. Remote sensing databases were used to determine environmental conditions of sea surface temperature, chlorophyll, productivity, upwelling and frontal index at each location and values in areas searched were compared with those for locations when sharks were transiting. Environmental conditions of specific water temperature and productivity were associated with the searching behavioral mode indicating that mako sharks orient towards a specific set of water conditions for presumably engaging in foraging behavior.

 

 

0121 AES Ichthyology, Carson 2, Thursday 16 July 2015

Allen Andrews 1, Michelle Passerotti 2, Lisa Kerr 3, Lisa Natanson 4, Sabine Wintner 5

1  NOAA Fisheries – PIFSC, HI, USA, 2 NOAA Fisheries – SEFSC, FL, USA, 3 Gulf of Maine Research Institute, ME, USA, 4 NOAA Fisheries – NEFSC, RI, USA, 5 KwaZulu- Natal Sharks Board, Durban, South Africa

 

Maximum Age and Missing Time in Shark Vertebrae: The Limits and Validity of Age Estimates Using Bomb Radiocarbon Dating

 

Bomb radiocarbon dating has become a common tool in determining valid measures of age for large shark species. In most cases, estimates of age were made by counting growth-band pairs in vertebrae and usually in the corpus calcareum of vertebral cross- sections. These estimates of age have been either supported or refuted using measured radiocarbon values (reported as ∆14C) that are equated to a year-of-formation, and subsequently compared to an appropriate ∆14C reference record. While the approach seems straightforward, the application is not and an effective ageing project may require some significant assumptions that are sometimes overlooked. Two of the most important considerations are the sources of carbon available to the vertebrae and the use of a valid ∆14C reference to provide validated age estimates. Recent findings for some species indicate the vertebrae cease growth and as a consequence ages have been underestimated by decades (i.e. sand tiger shark, Carcharias taurus). However, proper alignment of the ∆14C measurements from vertebral samples to the ∆14C reference record does not always provide well-defined ages and many are still considered estimates that require some assumptions (i.e. white shark, Carcharodon carcharias). The aim of this presentation is to provide an overview of how bomb radiocarbon dating can work for shark vertebrae with some insight on how the method can fall short of expectations.

 

0445 AES Ichthyology, Carson 2, Thursday 16 July 2015

Mark Grace 1, Michael Doosey 2, Henry Bart 2, Gavin Naylor 3, John Denton 4

1 NOAA/NMFS, Pascagoula, MS, USA, 2 Tulane University Biodiversity Research Institute, Belle Chasse, LA, USA, 3 Hollings Marine Institute, Charleston, SC, USA, 4 American Museum of Natural History, Central Park West @ 79th Street, New York, NY, USA

 

First Record of a Pocket Shark (Mollisquama sp.) from the Gulf of Mexico

 

Kitefin sharks of the family Dalatiidae (Squaliformes) comprise 7 genera of which five are monotypic; the highest percentage of monotypic genera for any family in the order Squaliformes. One of the rarest monotypic dalatiids, Mollisquama parini Dolganov, 1984 was described from a single female specimen collected from the Nazca Submarine Ridge in the southeast Pacific Ocean. A second Mollisquama specimen was captured during a 2010 midwater trawl survey of the northern Gulf of Mexico conducted by NOAA/NMFS Southeast Fisheries Science Center, Mississippi Laboratories. Both the holotype of M. parini and the Gulf of Mexico specimen possess the remarkable pocket gland with its large slit-like external opening located just above the pectoral fin. Features found on the Gulf of Mexico specimen that were not noted in the description of M. parini include a series of ventral photophore agglomerations and a modified dermal denticle surrounded by a radiating arrangement of denticles just posterior to the mouth. Phylogenetic analysis of NADH2 gene sequences places Mollisquama sister to Dalatias plus Isistius within the family Dalatiidae.

 

0313 AES Ichthyology, Carson 2, Thursday 16 July 2015

Victoria Elena Vásquez 1, David A. Ebert 1, Douglas J. Long 2

1Pacific Shark Research Center, Moss Landing Marine Laboratories, Moss Landing, C A, USA, 2 Department of Biology, St. Mary’s College, Moraga, CA, USA

 

A New Lanternshark (Squaliformes: Etmopteridae: Etmopterus) from the Eastern Central Pacific Ocean

 

A new species of lanternshark shark, genus Etmopterus is described from specimens collected off the Pacific coast of Central America. The new species is placed in the ‘Etmopterus spinax’ clade by a lack of flank markings and small hook-like conical dermal denticles distributed throughout the body. This new species can be separated from its congeners based on: proportional body measurements, meristic measurements of spiral valve and vertebral counts, arrangement of dermal denticles, and dark fin margins that contrast with other species in the ‘E. spinax’ clade, which typically possess white fin margins. The dorsal fins in the new species are much similar in size compared with its congeners while the second dorsal spine is significantly larger than the first, as is typical for the genus. The dark coloration of this new species makes photophore markings difficult to identify. However, the dorsal portion of the head is unique from other Etmopterus in possessing parallel linear markings with a light brown patch in between. The head portion is also distinct from other members of the ‘E.spinax clade’ in having a dense concentration of dermal denticles closely surrounding the eyes, mouth, gills and spiracles. This is the only Etmopterus species presently known from the Pacific coast of Central America.

 

AES Reproduction & Genetics, Carson 2, Friday 17 July 2015 Morning

 

0184 AES Reproduction, Carson 2, Friday 17 July 2015

Keiichi Sato 1, Masaru Nakamura1, Taketeru Tomita 2

1 Okinawa Churashima Research Center, Motobu, Okinawa, Japan, 2 FSU Coastal and Marine Laboratory, St. Teresa, FL, USA

 

Nourishment of White Shark Embryos with Uterine Milk during the Early Gestation Period

 

The white shark, Carcharodon carcharias, demonstrates viviparous and oophagous modes of reproduction. Morphological and histological observations of a 4,950mmTL gravid female accidentally caught by fishermen in the Okinawa Prefecture, Southern Japan revealed that the shark had conceived six embryos (543-624 mm), and also contained copious amounts of yellowish viscoid uterine fluid as well encased nutrient eggs and broken egg cases in both uteri. Although ruptured, the six embryos had large stomachs, and the mean volume of the stomachs was approximately 197.9mL. About 20 rows of potentially functional teeth were present in the upper and lower jaws. Periodic Acid Schiff-positive substances were observed on the surface and in the cytoplasm of the epithelial cells, and large, secretory, OsO4-oxidized lipoid droplets of various sizes were distributed on the surface of the villous string epithelium on the uterine wall. These histological observations demonstrated that the uterine wall was comprised of villous structures, similar to the trophonemata of nourishing embryos of dasyatid rays, thereby suggesting that the large amount of fluid found in the uterus of the white shark was required for embryo nutrition. Hence, the following conclusions were drawn: (1) the uterine fluid is secreted from the uterine villi, (2) the embryos are able to use abundant uterine fluid and encased nutrient eggs for nutrition at this stage, and (3) the uterine fluid is the major source of embryonic nutrition before oophagy onset.

 

0328 AES Reproduction, Carson 2, Friday 17 July 2015

Melissa Gonzalez De Acevedo, Jim Gelsleichter

University of North Florida, Jacksonville, FL, USA

 

Hormone Regulation of Sperm Storage in Female Bonnethead Sharks (Sphyrna tiburo)

 

Female sperm storage is a phenomenon that has evolved in many different taxa, allowing viable sperm to be retained in the reproductive tract for an extended time period. Previous studies have determined that reproductive hormone may play an important role in regulating various aspects of sperm storage in certain vertebrates, including the long-term survival of sperm and its release near the end of the storage period,. However, to date, no published studies have investigated the hormone regulation of sperm storage in the reproductive tract of female elasmobranchs despite evidence for this phenomenon in several shark species. Therefore, the purpose of this study was to investigate if gonadal steroid hormones such as 17β-estradiol, androgens, and progesterone, which have been shown to increase in circulation during various periods of sperm storage, may play in regulating this poorly understood process. To accomplish this, circulating concentrations of gonadal sex hormones and the distribution of sex steroid receptors in the oviducal gland, the sperm storage organ of female sharks, were examined in the bonnethead (Sphyrna tiburo), an annually-reproducing species known to store sperm for a 3-6 month period between copulation and ovulation/fertilization. As demonstrated in previous studies, female bonnetheads exhibited increases in circulating steroid concentrations both during (testosterone, 17β- estradiol) as well as near the end (progesterone) of the sperm storage period. Immunocytochemical analysis of androgen, estrogen, and progesterone receptors in the oviducal gland demonstrated that epithelial cells of sperm-storage tubules and spermatozoa itself are direct targets for these hormones.

 

0394 AES Reproduction, Carson 2, Friday 17 July 2015

Brenda Anderson 1, Carolyn Belcher 2, JoAnn Slack 3, James Gelsleichter 1

1 University of North Florida, Jacksonville, FL, USA, 2 Georgia Department of Natural Resources, Brunswick, GA, USA, 3University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA, USA

 

The Use of Ultrasonic Imaging to Detect Reproductive Activity in Female Bonnetheads (Sphyrna tiburo)

 

Ultrasonography has become a widely used diagnostic tool in the veterinary field, following its introduction to obstetrics in humans in the 1960s. Traditional methods for investigating shark reproduction include euthanasia and dissection, which is not conducive to studying large or endangered sharks and are usually fatal to embryos. Ultrasound machines have not been widely used in shark research due to the machine's fragile construction. The purpose of this study was to determine reproductive activity in female bonnetheads (Sphyrna tiburo) using a field-ready ultrasound machine and to compare the "gold standard" dissection method to ultrasound methods by determining their level of agreement. Female sharks (n = 71) were collected, euthanized, externally examined via ultrasound, and uteri dissected to determine reproductive activity. Presence and number of eggs and/or embryos were recorded using 8 MHz linear and 5 MHz curvilinear transducers. Contents of the uteri were dissected and counted. Kappa statistic was used to compare the level of agreement between the different methods: dissection to curvilinear transducer, dissection to linear transducer, and linear to curvilinear transducers. Dissection versus curvilinear transducer methods resulted in 88.9% agreement (Kappa coefficient = 0.7798). Dissection versus linear transducer methods resulted in 61.3% agreement (Kappa coefficient = 0.4192). Linear versus curvilinear transducer methods resulted in 97.3% agreement (Kappa coefficient = 0.9510). Overall, the ultrasound was a good indicator of presence of eggs/embryos in the bonnethead. Limitations of ultrasonography include image quality, gut content interference, and stacking of pups in utero.

 

0085 AES Genetics, Carson 2, Friday 17 July 2015

Hayley DeHart 1, Gavin Naylor 1, Bryan Frazier 2

1 College of Charleston, Charleston, SC, USA, 2 South Carolina Department of Natural Resources, Charleston, SC, USA

 

Comparing Demographic and Genetic Estimates of Population Sizes in Three Coastal Shark Species

 

Sharks are widely held by the scientific community to be threatened with extinction, and yet they remain some of the most poorly understood marine vertebrate organisms. There is belief among marine conservation biologists that population genetics based approaches can be used to distinguish species, populations, and even population sizes for these threatened animals. Estimating population sizes using multiple estimates, as well as multiple species, is critical to understanding true population sizes and life history traits that affect these estimates. This study aims to estimate census population size (Nc) and compare this demographic value to the genetically determined effective number of breeders (Nb). Census size will be estimated from an on-going demographic mark and recapture study conducted by South Carolina Department of Natural Resources and estimated using the program MARK. Effective number of breeders will be estimated using a cross-species gene capture method and variability will detected in these data to estimate effective number of breeders using the program NeEstimator. These methods will be deployed on three separate shark species: bonnetheads (Sphyrna tiburo), finetooth sharks (Carcharhinus isodon), and sandbar sharks (Carcharhinus plumbeus). These species all exhibit different population structure, life history, and recapture rates, which may in turn affect their Nb/Nc ratio, a value that may be used for future conservation regulation. It is believed that the comparisons between these estimates and species may be used for population assessment and management of coastal shark species.

 

0203 AES Genetics, Carson 2, Friday 17 July 2015

Drew Duckett, Gavin Naylor

College of Charleston, Charleston, SC, USA

 

Maximizing Statistical Power in Shark Population Structure Analyses

 

Next Generation Sequencing technologies developed in recent years allow for the collection of substantially more DNA sequence data than has previously been possible. However, the comparative utility of the various kinds of molecular markers now available for exploring population genetic questions has not yet been thoroughly evaluated. Few population genetics studies test the statistical power of the marker types used or the sampling schemes employed for answering the question posed. Using too few loci, the incorrect marker type, or inadequate sampling can severely compromise the statistical significance of research findings obtained. The present study explores the differences in statistical power associated with different molecular marker types, different numbers of marker loci, and different sampling schemes for analyzing population structure. These issues are addressed through both computer simulation and empirical data sets of three shark species with different life history characteristics. The results of the present study will serve to guide researchers as to which markers are most appropriate for different kinds of questions and increase knowledge of the population structures of the shark species evaluated.

 

0273 AES Genetics, Carson 2, Friday 17 July 2015

David Portnoy 1, Jonathan Puritz 2, Christopher Hollenbeck 2, John Gold 2

1 Texas A&M University - Corpus Christi, Corpus Christi, TX, USA, 2 Harte Research Institute, Corpus Christi, TX, USA

 

Adaptive Genetic Variation and Male-mediated Gene Flow in the Bonnethead

 

The combination of male-biased dispersal and female philopatry, common in sharks, is expected to homogenize genetic variation in nuclear sequences across geographic space relative to variation in mitochondrial (mt)DNA sequences. However, when site-fidelity occurs across a heterogeneous environment, local selective regimes may add complexity to this pattern and on a genome-wide scale. We examined this possibility in bonnetheads, a species known to exhibit site fidelity. We obtained samples of bonnetheads from three areas along the west (Gulf) coast of Florida and one area off North Carolina on the U.S. Atlantic coast. We assessed patterns of variation in each sample in sequences of mtDNA and in 5,914 nuclear-encoded single nucleotide polymorphisms (SNPs). Sequences of mtDNA and putatively neutral SNPs revealed male-mediated gene flow and female philopatry among the samples from the Gulf. A total of 45 ‘outlier' SNPs (O-SNPs) were identified, and allele frequencies for 20 O-SNPs were correlated significantly with latitude, suggesting localized adaptation. There were no fixed differences in allele frequencies at any O-SNP locus; combinations of alleles common in one sample were present in low frequencies in other samples. There also was a significant correlation between estimates of genetic divergence based on O-SNPS and mtDNA sequences, but not between mtDNA sequences and either O-SNPs or putatively neutral SNPs. These results indicate that localized adaptive variation may sort primarily through the philopatric sex (females), with the dispersing sex (males) facilitating movement of potentially adaptive variation among locations and/or environments.

 

AES Biogeography/AES Gruber, Carson 2, Friday 17 July 2015 Morning

 

0406 AES Biogeography, Carson 2, Friday 17 July 2015

Toby Daly-Engel 1, Dean Grubbs 2, Rebecca Varney 1, Erin Pereira 1, Shawn Larson 3

1 University of West Florida, Pensacola, FL, USA, 2 Florida State University, Tallahassee, FL, USA, 3 Seattle Aquarium, Seattle, WA, USA

 

Strange Things Happen When You Turn Back the Molecular Clock: Evolution and Speciation in Sixgill Sharks (Genus Hexanchus)

 

It is largely unknown what selective forces impact evolution and speciation in the deep ocean, though this ecosystem is thought to be largely unchallenged by climatic change relative to shelf and coastal habitat. Fossil records and recent genetic analyses indicate that sixgill sharks (Hexanchus, Hexanchidae) are members of the first extant shark taxon to emerge following the shark batoid-split approximately 300 MYA. Unlike other Squalomorph lineages, many of which moved inshore to shallower shelf habitat and consequently diversified widely over evolutionary time, sixgills remain a primarily deep-water group, which may have contributed to their low speciation rates. Here we explore the factors that shape sixgill shark diversification in the deep ocean. DNA was collected from 130 Hexanchus griseus and 9 H. nakamurai from 13 collection sites across a global range. We sequenced four mitochondrial and nuclear genes plus 11 microsatellite loci, and found low molecular diversity across the genome relative to other shark species of a similar size. Coalescent analysis indicates a deep evolutionary split within H. griseus resulting in multiple well-defined global clades, one Indo-Atlantic and one restricted to the Pacific. We also show a deeper split within H. nakamurai that has resulted in at least one previously-unknown cryptic species, located in the West Indian Ocean. A molecular clock for the mtDNA control region and calibrated to the emergence of the Isthmus of Panama confirmed that rates of evolution in sixgills is dramatically lower than that of other shark taxa.

 

0466 AES GRUBER AWARD, Carson 2, Friday 17 July 2015

Kristin A. Walovich, David A. Ebert

Moss Landing Marine Laboratories, Pacific Shark Research Center, Moss Landing, CA, USA

 

A Revision of the Short-nose Chimaeras (Genus Hydrolagus) from Southern Africa: Conservation and Management Implications of an Enigmatic Fish Group

 

A lack of taxonomic clarity has negative implications for many facets of chondrichthyan research including proper identification, acquisition of basic life history information, and the implementation of fishery management and conservation efforts. The Order Chimaeriformes, also known as ghost sharks or chimaeras, is an enigmatic and understudied group of fishes particularly vulnerable to impacts of deep-sea fisheries. This vulnerability is compounded by taxonomic uncertainties and a paucity of life history information, especially for chimaeras of the genus Hydrolagus (Family Chimaeridae) from the southern African region. Given historical and current taxonomic ambiguity and its impacts on management and conservation, the main objective of this study is to provide a qualitative, quantitative and genetic assessment of the diversity of the genus in the Southern African region. Full elucidation of species composition will enable the development and dissemination of reliable identification material and range maps to improve fisheries statistics, initiate ecological research and facilitate appropriate conservation efforts.

 

0561 AES GRUBER AWARD, Carson 2, Friday 17 July 2015

Paul J. Clerkin 1, Jenny M. Kemper 2, David A. Ebert 1

1 Pacific Shark Research Center, Moss Landing Marine Laboratories, Moss Landing, CA, USA, 2 Hollings Marine Lab, Medical University of South Carolina, Charleston, SC, USA

 

Investigation and Taxonomy of Southwestern Indian Ocean Chimaeridae

 

Historically understudied, the Chimaeriformes (Chondrichthyes: Holocephali) has received increased attention over the past decade and half, with the expansion of deep- sea fisheries, with 19 species having been described. Despite this recent focus, 59% of all known chimaeras are data deficient as accessed by the IUCN. This lack of information is due to taxonomic uncertainty and the intrinsic complexities associated with sampling at great depth in remote areas. The Southwestern Indian Ocean (SWIO) offshore ecosystem is a poorly explored, remote region characterized by extreme topology that includes the massive Madagascar Ridge. This region is punctuated by seamounts that function as isolated underwater islands, supporting high abundance of fish, and a number of chimaera species. Currently, very little is known about SWIO Chimaeras, since only two species have been verified from the area, Hydrolagus africanus, and Chimaera notafricana. During two surveys (2012 and 2014) onboard a commercial deep-sea trawler in the SWIO offshore, six distinct species of Chimaeridae (4 Chimaera, 2 Hydrolagus) were collected. A comprehensive set of morphometric and meristic measurements, and genetic samples were collected from each specimen encountered. Comparisons with geographic congers using standard morphological methods along with comparative genetic samples were made between SWIO offshore chimaeras and those from South Africa, Australia, and New Zealand to investigate similarities and differences between these geographical regions. Taxonomic resolution of this enigmatic Chondrichthyan group will lead to improved species-specific identification.

 

0291 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Matthew Jew, David A. Ebert
Moss Landing Marine Laboratories, Moss Landing, CA, USA

Redescription of the Bigeye Chimaera, Hydrolagus macrophthalmus, de Buen, 1959, (Chimaeriformes: Chimaeridae), with Comments on the Family Chimaeridae from the Southeastern Pacific Ocean

Hydrolagus macrophthalmus de Buen, 1959 is a little known chimaeroid species from the Southeastern Pacific Ocean. It was described based on two specimens by Fernando de Buen, and at the time it was the only chimaeroid species, other than Callorhinchus callorynchus (Linnaeus, 1758) known from the region. At least four other species are now known to occur in the area therefore making improved identification between species all the more important. Hydrolagus macrophthalmus can be distinguished from the other regional species by a combination of uniform height of the elongated second dorsal fin, a long curved first dorsal fin spine that extends past the origin of the second dorsal fin when laid flat and uniform dark brown coloration with no light markings or spots laterally on the body. The species is compared to four other species reported to occur in the Southeastern Pacific Ocean: H. alphus, H. melanophasma, H. mccoskeri and H. trolli. Improved identification of Southeastern Pacific Ocean chimaeras will help in developing better management practices and conservation of these little known Chondrichthyans.

0609 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
James Anderson 1, Kim Holland 2
1 University of Hawaii, Honolulu, HI, USA, 2 Hawaii Institute of Marine Biology, Kaneohe, HI, USA

Holy Grail, Needle in a Haystack, or Wild-Goose Chase: Searching for a Shark Magnetoreceptor

The physical basis of magnetic field perception in both vertebrates and invertebrates has been the subject of debate for some time, with three hypotheses prevailing above others. The elasmobranch fishes (sharks, skates and rays) are the only class hypothesized to use their electrosensory capability in the perception of geo-magnetic stimuli. Other taxa argued to orient to or via the geomagnetic field have been hypothesized or demonstrated to use alternative mechanism. One such theory is the magnetite hypothesis, whereby intracellular crystals of the iron oxide magnetite (Fe3O4) are coupled to mechanosensitive channels that give rise to neuronal activity in specialized sensory cells. Efforts to find these primary sensory structures have failed to convincingly describe receptor locations, illustrating the need to develop new methods to test the magnetite hypothesis of magnetoreception. Here we describe an ongoing study that aims to identify and describe suitable candidate sensory cells in both the olfactory and vestibular organs of the Scalloped Hammerhead shark (Sphryna lewini). We report upon the efficacy of a novel approach to identify candidate cells, and in turn report efforts to both quantify and qualify cells with magnetic properties that could function in the perception of magnetic stimuli.

0179 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Kyle Newton

Florida Atlantic University, Boca Raton, FL, USA

The Yellow Stingray, Urobatis jamaicensis, Has a Magnetic Sense but Can It Use the Geomagnetic Field to Derive a Sense of Location?

The strength and inclination angle of the geomagnetic field vary predictably with latitude and magnetically sensitive animals can use these cues to derive a sense of location during migrations. Our previous work has demonstrated that the yellow stingray, Urobatis jamaicensis, can detect magnetic fields from permanent magnets. However, it is unknown if elasmobranchs can detect changes in the strength or inclination angle of a magnetic field. Stingrays were placed into two treatment groups that experienced magnetic stimuli that were 2.5X the range of possible magnetic field values that this species might encounter across its distribution. Stimuli were generated by a Merritt four-coil electromagnet system and the initial response of naive rays to stimuli served as a control. Individual stingrays were trained to swim to a feeding station when the magnetic field strength was increased by 45 μT or the inclination angle was shifted vertically by 75°. Once the rays learned the task the stimulus intensity was gradually reduced in order to determine the threshold for a behavioral response. Rays were then subjected to stimuli from the other treatment group to determine if the rays could discriminate between the two stimuli.

0261 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Mariah O. Pfleger 1, R. Dean Grubbs 2, Toby S. Daly-Engel 1
1 University of West Florida, Pensacola, FL, USA, 2 Florida State University, Tallahassee, FL, USA

The Dogfish Formerly Known as Mitsukurii: A New Deep-water Shark Species from the Gulf of Mexico

The shortspine spurdog shark (Squalus mitsukurii) is a putative circumglobal deep-water shark that was originally described from Japanese waters. Sharks of the genus Squalus are easily misidentified due to the high degree of morphological similarity with their congeners. Recent taxonomic research on this species from the Pacific has indicated that S. mitsukurii may actually comprise a species complex, a group of separate but closely related species. Using approximately 680 bp of mitochondrial cytochrome c oxidase 1 (barcoding gene) we found 99.61% bootstrap support for the separation of the Gulf of Mexico Squalus cf mitsukurii from Squalus mitsukurii in Japan. We found similar support using 595 bp of mitochondrial NADH dehydrogenase 2 (ND2), as well as morphological characters. The new species in the Gulf of Mexico is named Squalus clarkae in honor of Dr. Eugenie Clark.

0606 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Joseph Bizzarro 1, Simon Brown 2, Heather Robinson 2, David Ebert 2, Adam Summers 1
1 University of Washington, Seattle, WA, USA, 2 Pacific Shark Research Center, Moss Landing, CA, USA

How Can There Be So Many Skate Species?

Skates (Rajiformes: Rajidae) are an extremely diverse group of cartilaginous, marine fishes; yet, they have historically been considered to occupy unconsolidated habitats and serve similar trophic roles. The hypothesis of ecological redundancy in skates was evaluated using diet composition data from two eastern North Pacific skate assemblages (central California, western Gulf of Alaska). Species-specific diet compositions differed significantly in both regions, supporting the alternative hypothesis of trophic separation in skates. The timing and location of hauls was the most important consideration in explaining the substantial dietary variability in each assemblage and reinforces the perception that skates are generalist predators. Dispersion analyses were highly significant, however, indicating additional extreme within-group variability in skate diet among these variables. Canonical correspondence analysis was used to associate specific variable factors with prey taxa and supported the general concept of greater piscivory and less reliance on small crustaceans with increasing total length. Diet composition and trophic level of Beringraja binoculata and Raja rhina differed considerably between regions and indicated a greater reliance on crustaceans in Alaska and fishes in California. These results, coupled with those of a complementary study of spatial relationships, demonstrate that skates are more ecologically diverse than previously reported. Pronounced differences in core resource use across broad, overlapping spectrums of trophic and spatial tolerances: 1) probably facilitate the coexistence of speciose skate assemblages, and 2) may explain the remarkable taxonomic diversity in this group. Ecological studies and fishery management plans that incorporate ecosystem considerations should incorporate species-specific data for skates.
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AES GRUBER AWARD Continued, Carson 2, Friday 17 July 2015 Afternoon

0135 AES GRUBER AWARD, Carson 2, Friday 17 July
201 Brendan Talwar 1, Edward Brooks 2, Alp Gokgoz  2, John Mandelman 3, Dean Grubbs 1

Florida State University, St. Teresa, FL, USA, 2 Cape Eleuthera Institute, Rock Sound, Eleuthera, Bahamas, 3 New England Aquarium, Boston, MA, USA

Stress Physiology and Post-release Survivorship of Cuban Dogfish and Gulper Sharks Caught on Longlines

Cuban dogfish (Squalus cubensis) and gulper sharks (Centrophorus cf. uyato) are common bycatch in deepwater longline fisheries, yet their fate after release is entirely unknown. Given the highly variable nature of a deepwater longline haul and the documented interspecific differences in the elasmobranch stress response, this research investigates (i) the 24hr post-release survivorship rates of S. cubensis and C. cf. uyato, (ii) the potential factors contributing to mortality, and (iii) the suitability of caging as a method to address these aims. To meet these objectives, individuals were caught on longlines in Exuma Sound, The Bahamas, and lowered to their respective capture depths (450-900m) in a video-monitored cage. Squalus cubensis experienced a 43.8Ī0.73% 24hr post-release survivorship rate whereas C. cf. uyato experienced 100% mortality. A logistic regression analysis showed that at-vessel blood pH and release condition could predict survivorship for S. cubensis, whereas glucose and lactate could not. Caging had no significant effect on S. cubensis mortality; in comparison, C. cf. uyato commonly lost the ability to orient within the cage prior to mortality. The exact drivers of this trend are unclear. This study greatly improves our understanding of discard mortality for deep sea sharks and offers a first characterization of the stress response for two common bycatch species. It also suggests that containment studies may not be appropriate for the genus Centrophorus.

0222 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Cassandra Ruck 1, Fabio Hazin 2, Rima Jabado 3, Mahmood Shivji 1
1 Save Our Seas Shark Research Center USA, Nova Southeastern University, 8000 N Ocean Drive, Dania Beach, FL, USA, 2 Universidade Federal Rural de Pernambuco, Recife, PE 52171-032, Brazil, 3 Gulf Elasmo Project, P.O. Box 29588, Dubai, United Arab Emirates

Global Genetic Connectivity in a Shark of High Conservation Concern, the Oceanic Whitetip, Carcharhinus longimanus

The oceanic whitetip shark, Carcharhinus longimanus, is globally distributed in warm waters and has suffered drastic declines in recent history due to high bycatch in diverse pelagic fisheries and demand for its large fins in international trade. Due to these declines, the once common oceanic whitetip is now listed as "Critically Endangered" in the Western North and Western Central Atlantic and "Vulnerable" to extinction globally by the IUCN Red List. Thus, there are urgent calls for improved data collection and management strategies to conserve this enigmatic species. However, there exist no data on the population genetics of oceanic whitetip sharks. We report an assessment of the global population structure and demographic history of this shark based on analysis of two mitochondrial DNA region sequences (entire control region (1067 bp) and part of the NADH dehydrogenase subunit 4 gene (682 bp) and nuclear microsatellite markers. Pairwise analysis of concatenated mitochondrial data with ARLEQUIN v. 3.5.1.2 indicates significant differentiation between the western Atlantic (n=93) and Indo-Pacific (n=72) populations (ΦST = 0.0757, P<0.001). Furthermore, analysis of only the 682 bp ND4 fragment, a more variable locus than the control region in this species, indicates differentiation between all three ocean basins: Atlantic vs. Pacific (n=40) (ΦST = 0.0804 , P< 0.001), Atlantic vs. Indian (n=32) (ΦST = 0.0508, P=0.0108), Indian vs. Pacific (ΦST =0.0509, P=0.033). Despite the global distribution and presumably high vagility of C. longimanus, significant population structure exists and effective management strategies must take this into consideration.

0306 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Charles Bangley, Roger Rulifson

East Carolina University, Greenville, NC, USA

Is Pamlico Sound, North Carolina a "New" Nursery Habitat for the Bull Shark (Carcharhinus lecuas)?

The bull shark (Carcharhinus leucas) is a seasonal visitor to North Carolina nearshore and estuarine waters, but juveniles have historically been rare in the state's waters. Catch and environmental data from North Carolina Division of Marine Fisheries gillnet and longline surveys were used to determine the suitability of Pamlico Sound as bull shark nursery habitat. All sharks were classified as adult, age 1+, or neonate based on recorded total length (mm). Generalized linear models were used to identify environmental and spatial factors related to the presence of each bull shark demographic. From 2007-2014, a total of 48 bull sharks were captured within the sound, of which 36 fell within age 1+ or neonate ranges. Bull sharks within juvenile length ranges were not captured prior to 2011, but were documented every year since. Environmental preferences did not differ significantly between age 1+ and neonate sharks, but adults were found at significantly greater depths and in closer proximity to inlets. Juvenile bull shark abundance was significantly related to temperature and salinity. Significant increases in mean water temperature and decreases in mean salinity occurred in Pamlico Sound from 2007-2014, particularly in May and June when parturition occurs in other bull shark nurseries. These environmental changes may have created favorable conditions for a bull shark nursery in Pamlico Sound.

0393 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Bryan Keller 1, Jean-Sebastien Finger 2, Tristan Guttridge 2, Samuel Gruber 2
1 Coastal Carolina University, Conway, SC, USA, 2 Bimini Biological Field Station, Bimini, Bahamas, Bahamas

Energetic Savings During Group Participation and the Influence of Swimming Speed on Partner Preference in the Juvenile Lemon Shark, Negaprion brevirostris

Grouping in sharks is well-known, however, there are few quantitative analyses on the mechanisms that drive their formation. In this study we use controlled semi-captive behavioral experiments to assess the potential role that swimming speed and energetic efficiency plays in the group formation and social behavior of a large marine vertebrate. Juvenile lemon sharks, Negaprion brevirostris, in Bimini, Bahamas were captured, measured, tagged with external color codes for individual recognition, and housed in pens that exposed them to ambient conditions. Sharks were introduced into a social network pen while an overhead video system recorded behaviors for one hour. Tracking software transformed their movement patterns into a coordinate system. Multiple algorithms were used to analyze these coordinates, and a matrix of interactions was produced demonstrating when sharks were following or paralleling other individuals. When individuals were engaged in a following behavior, swimming speed was calculated for both animals while ensuring the distance between the two was constant. Similarly, an investigation was conducted to determine if interacting sharks select each other based upon swimming speed. Preliminary results suggest that juvenile lemon sharks show an active partner preference for animals with a similar swimming speed and that energy is conserved while closely following a conspecific. This research advances our understanding of the mechanisms driving group formation in lemon sharks, a model species for large marine predators.

0330 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Connor White 1, Yukun Lin 2, Jerry Hsiung 2, Christopher Clark 2, Christopher Lowe 1

1 California State University Long Beach, Long Beach, CA, USA, 2 Harvey Mudd College, Claremont, CA, USA

Habitat Selection of the Leopard Shark, Triakis semifasciata, Using Fine Spatio-Temporal Movement and Temperature Data

Environmental conditions are largely considered to be drivers of elasmobranch movements and behaviors. However, conditions are in constant flux and can be highly variable over small spatial extents. Thus to understand how individuals interact with surrounding environmental conditions, researchers must be able to measure the movements of individuals and environmental conditions at high spatio-temporal resolutions. We developed an autonomous underwater vehicle (AUV) designed to actively track an acoustically tagged elasmobranch, providing better spatial accuracy than a human (AUV: 6.1 Ī 4.8 m, Researcher: 16.6 Ī 9.7 m, F = 31.1, p = 0.005), while generating significantly more localizations (AUV: 45.2 Ī 10.5 detection/min, Researcher: 12.2 Ī 9.1 detections/min, t2.41= 3.96, p = 0.04). These positions were further refined by integrating magnetic heading of the animal provided by animal-borne inertial measurement units (IMU). Using this system 5 leopard sharks were tracked in Big Fisherman’s Cove (BFC), Catalina Island. Seafloor temperature was collected every 5 min from 20 locations in the cove to derive interpolated temperature maps. Comparing the fine-scale shark movements with the fine-scale temperatures availability in the cove, showed leopard sharks disproportionately utilized warmer areas of the cove (χ2 =432.3, p <0.001). By utilizing tools that provide fine-scale information on the movement and behaviors of animals, researchers will be able to begin to tease apart how elasmobranchs interact with their environment, and ultimately, how these interactions structure the distributions of species.

0042 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
David Shiffman, Catherine Macdonald, Harry Ganz, Neil Hammerschlag
University of Miami, Miami, FL, USA

Initial Assessment of the Scale, Practices and Conservation Implications of Land-Based Shark Fishing in South Florida

Angling for sharks from beaches is a popular recreational activity in Florida, but the scale, practices, and conservation implications remain unknown. Here we analyze thousands of posts made by land-based shark anglers on the public online discussion board of a local fishing club in order to assess angler attitudes, perceptions and practices. We found that land-based shark anglers are generally young (under 30) and male, a demographic different from most recreational anglers. These anglers enjoy land- based shark fishing because it is more affordable than boat-based fishing, but still allows people to catch and interact with large and exciting fish. Though there is some skepticism of government-led scientific population estimates, land-based shark anglers are aware of and concerned by global shark population declines. Conflicts between beach stakeholders (swimmers and anglers) are frequently discussed. These anglers believe that regulations which restrict recreational angling for overfished species are unjust because they believe commercial fishing is what caused the population declines. Land-based shark anglers also frequently discuss how laws that restrict land-based fishing, but not boat-based fishing (including beaches that ban fishing, and restrictions within state waters but not adjacent Federal waters), discriminate against lower income anglers. Land-based shark fishing raises some conservation concerns because of the increased physiological stress caused by the sharks being brought onto land. Additionally, there are numerous interactions with protected species like the physiologically sensitive great hammerhead. Potential policy and education solutions that minimize these conservation concerns and stakeholder conflicts while still allowing recreational anglers to fish are proposed.

0090 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Darcy Bradley 1, Eric Conklin 2, Yannis P. Papastamatiou 3, Douglas J. McCauley 4, Kydd Pollock 2, Amanda Pollock 5, Bruce E. Kendall 1, Steve D. Gaines 1, Jennifer E. Caselle 6

1Bren School of Environmental Science and Management, University of California Santa B arbara, Santa Barbara, CA, USA, 2 The Nature Conservancy, Hawai’i, Honolulu, HI, USA, 3 School of Biology, Scottish Oceans Institute, University of St Andrews, St Andrews, Scotland, UK, 4 Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA, 5 U.S. Fish and Wildlife Service, Honolulu, HI, USA, 6 Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA

Managing a Moving Target: A Spatially Explicit Capture-recapture Reef Shark Population Density Estimate at an Unfished Coral Reef

Baseline population estimates are lacking for most species of reef shark. The grey reef shark (Carcharhinus amblyrhynchos), which is listed as Near Threatened on the IUCN Red List of Threatened Species, is highly mobile and therefore particularly difficult to monitor. At the same time, its mobility is precisely what has stymied its protection in much of the world – without understanding the spatial behavior of reef sharks, it is impossible to design spatial management strategies to protect them. Shark abundance through both space and time can be better estimated by directly accounting for reef shark movement in population estimates without the biases inherent in diver-based visual surveys. A spatio-temporal understanding of animal movement and abundance also allows managers to identify critical habitats, movement between habitats, and track changes to population size and structure. To directly address and incorporate animal movement in estimates of reef shark population size and density, we used a spatially explicit capture-recapture model from an eight year capture-recapture program augmented with telemetry data to produce the first baseline population density estimate of grey reef sharks and to further describe their spatial and temporal distribution at Palmyra atoll, a remote U.S. National Wildlife Refuge in the central Pacific Ocean. We found that diver based visual surveys had significantly over estimated shark density at an island wide scale. While our analysis revealed density ‘hot spots’, sharks also underwent regular excursions around the atoll, indicating that large scale spatial protection is necessary to recover reef shark populations globally.

0164 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Alexander Hansell 1, Steve Kessel 3, Lauran Brewster 4, Steve Cadrin 1, Greg Skomal 5, Samuel Gruber 6, Tristan Guttridge 2
1 University of Massachusetts - Dartmouth, Fairhaven, MA, USA, 2 Bimini, Biological Field Station, Bimini, Bahamas, 3 University of Windsor, Windsor, Canada, 4 University of Hull, Hull, UK, 5Massachusetts Division of Marine Fisheries, New Bedford, MA, USA, 6 Rosenstiel School of  Marine and Atmospheric Science, Miami, FL, USA

Coastal Shark Assemblage, 11 – Year Fishery-Independent Shallow Water Longline Survey in Bimini, Bahamas

Understanding population dynamics is essential for implementing effective conservation and management of coastal sharks. Fishery-independent surveys can offer valuable information for data-limited situations. An 11-year (2004-2014) standardized, shallow water longline assessment was conducted monthly in the eastern coastal waters of Bimini, Bahamas. Each survey was comprised of five longline sets of 15 hooks with a soak time of 24 hours. A total of 684 sharks from nine species were caught over the course of the study with tiger (Galeocerdo cuvier), nurse (Ginglymostoma cirratum), blacktip (Carcharhinus limbatus) and lemon (Negaprion brevirostris) sharks comprising 94.9% of the catch. Based on total length, the majority of tiger (91.3%), nurse (54.4%), and lemon (81%) sharks were immature, while most blacktip sharks (84.6%) were mature. A sexual bias was noted in the data. The tiger (77.3%) and blacktip (58.3%) sharks were more often female, while the majority of lemon (73%) and nurse (56.8%) sharks were male. Seasonal trends indicate an abundance of nurse, blacktip, and lemon sharks during the warmer months. Over the course of the study, there was an increase in the tiger shark population. Nurse, blacktip, and lemon shark numbers were relatively stable. Preliminary general additive models indicate that catch rates are influenced by month, year, temperature, tide, soak time, and lunar cycle.

0122 AES GRUBER AWARD, Carson 2, Friday 17 July 2015
Emily Meese, Christopher G. Lowe

CSU Long Beach, Long Beach, CA, USA

Finding a Resting Place: How Environmental Conditions Affect the Spatial Distribution of Benthic Elasmobranchs at Big Fisherman's Cove, Santa Catalina Island

Ectothermic elasmobranchs are known to seek out habitats and environmental conditions to optimize their energetic requirements. Spatial distribution patterns of three species, bat rays (Myliobatis californica), shovelnose guitarfish (Rhinobatos productus), and round stingrays (Urobatis halleri) were used to determine resting habitat within Big Fisherman’s Cove (BFC), Santa Catalina Island. Distribution patterns of individuals were determined via field observation surveys and related to detailed georeferenced habitat maps. All species were found associated with sand and vegetated/sand substrata; however, all three species selected their substrata disproportionally from what was available in the survey area within the cove (p < 0.001). Seafloor water temperatures were stratified by distance to the shoreline (range: 17-21 oC), and differed between two survey periods (fall 2013 and summer 2014). In the fall, there was a significantly higher density of all three species in areas with water temperatures ~18 oC (range: 17.0 – 20.75) (p < 0.001). Bat ray density increased in the summer around areas with temperatures between 20.25 – 20.75 oC in BFC, while they had a more random spatial distribution in the fall. All three species demonstrated a hierarchical habitat selection by prioritizing either substrata type or temperature ranges. Aggregating elasmobranchs can potentially be more susceptible to exploitation when at these sites. Therefore, understanding how individuals select their resting habitat and environmental conditions may provide managers with opportunities to provide better protection for these species.
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Poster Session I Reno Ballroom & Tahoe Room, Friday 17 July 2015 Afternoon

0093 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Darcy Bradley 1, Yannis P. Papastamatiou 2, Steven D. Gaines 1, Jennifer E. Caselle 3

1Bren School of Environmental Science & Management, University of California Santa B arbara, Santa Barbara, CA, USA, 2 School of Biology, Scottish Oceans Institute, University of St Andrews, St Andrews, Scotland, UK, 3 Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA

Do Non-extractive Human Impacts have Quantifiable Behavioral Effects on Palmyra’s Reef Sharks?

Shark behavior can bias abundance estimates from diver-based visual surveys, thereby leading to a flawed understanding of population trends through time. The presence of this bias in diver-based visual surveys is ubiquitous in reef shark abundance estimates generated for Palmyra and the greater central Pacific. Failing to account for behavioral effects may be problematic as in most places it is impossible to differentiate changes in estimated population abundance due to behavioral modifications and those resulting from fishing. In Palmyra, we can isolate and quantify the behavioral response of reef sharks to human activities as human use of the waters surrounding Palmyra has not been constant: from 2001 to the present scientific diving, boating, and provisioning activities have significantly increased on Palmyra’s reefs. We quantified each activity to create a spatially and temporally explicit human use map of Palmyra. We then used paired baited remote underwater visual surveys (BRUVS) in research (heavy-use) and non-research (no-use) sites to assess the impact of human presence on the behavior of three species of reef shark. We found significant differences in time of first arrival in frame (p<0.05) but not maximum number of individuals in frame (maxN) for all reef shark species between heavy-use and no-use sites. In sites with minimal human impact, sharks arrived sooner, indicating greater attraction to human activity in no-use sites. By quantifying reef sharks’ responses to human activities, we can correct biased population estimates produced from existing visual survey data throughout the central Pacific.

0293 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Beth Bowers, Stephen Kajiura
Florida Atlantic University, Boca Raton, FL, USA

Migratory Behavior of the Blacktip Shark (Carcharhinus limbatus)

The migratory behavior of the blacktip shark (Carcharhinus limbatus) in the Western Atlantic has been anecdotally described but not empirically studied. The sharks are thought to migrate from nursery areas along the southeastern coast of the United States in the summer, to South Florida, where they remain in large aggregations (up to 800 sharks km-2) from January to April before returning northward. The first recorded description of the blacktip shark migration states that they occur north of Cape Hatteras, NC “only as a rare stray.” Given that this description was published over 70 years ago, their range might have shifted poleward in response to warming ocean temperatures, as has been demonstrated in many other marine species. To investigate the current migratory pattern of this population, ten blacktip sharks were instrumented with acoustic transmitters, while they overwintered in South Florida, and passively tracked along the eastern coast in cooperation with the Florida Atlantic Coast Telemetry (FACT) and the Atlantic Cooperative Telemetry (ACT) networks. Seven of the ten individuals were detected after instrumentation. Three of those seven individuals were detected far north of the previously reported NC limit, off Delaware Bay, NJ (1) and Long Island, NY (2). Five individuals were detected at the original capture location in South Florida the following winter, including two of the sharks that were detected in Delaware Bay and Long Island. This study provides the first empirical evidence of blacktip sharks completing a full migration cycle and suggests that their northern limit may have expanded poleward.

0371 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Matthew Ajemian, Gregory Stunz
Harte Research Institute for Gulf of Mexico Studies, Texas A&M University-Corpus Christi, Corpus Christi, TX, USA

Migratory Behavior and Habitat Use of Large Sharks in the Western Gulf of Mexico

Large sharks serve as critical apex predators in many marine ecosystems around the world, yet the habitat requirements and migration patterns of these species remain poorly understood throughout much of their ranges. The growing demand for shark habitat use information has supported a proliferation of satellite biotelemetry studies. Despite the multitude of anthropogenic pressures in the region, few data exist on large shark movement patterns in the western Gulf of Mexico. In summer of 2014, four large sharks (2 Scalloped Hammerhead, Sphyrna lewini; 2 Tigers, Galeocerdo cuvier) were tagged and released near an offshore production platform and tracked with Smart Position or Temperature transmitters. Sharks were tracked for thousands of miles, and demonstrated some important ecosystem connections between nearshore locales and open waters of the Gulf of Mexico. While Scalloped Hammerheads provided more frequent reports and fidelity to the Texas continental shelf, Tiger Sharks exhibited larger dispersal patterns, including a cross-basin venture towards the Campeche escarpment (Mexico) as shelf waters cooled in December and a subsequent return to the Texas shelf. Tiger Sharks also demonstrated use of NOAA-designated Habitats Areas of Particular Concern such as the south Texas hard banks and the Flower Gardens National Marine Sanctuary. Our work highlights the connected nature of many seemingly disparate habitats within the Gulf of Mexico by large sharks and the importance of establishing satellite tagging programs for conservation and management purposes. Continued tagging efforts in 2015 will assess potential year-to-year variability in the movement and habitat use patterns observed to date.

0383 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Breanna Machuca 1, Kelley van Hees 2, David Ebert 2

1 California State University, Monterey Bay, Seaside, CA, USA, 2 Moss Landing Marine Laboratories, Moss Landing, CA, USA

Trophic Ecology of Coastal Elasmobranchs Using Stomach Content and Stable Isotope Analysis

Sharks and rays are apex predators that inhabit Elkhorn Slough, a tidally influenced estuary in Central California. These elasmobranchs use the Slough as a seasonal habitat and food source. These are upper trophic level predators that may be threatened by changes in their habitat, especially to their food source. Leopard sharks (Triakis semifasciata), bat rays (Myliobatis californicus), and thornback rays (Platyrhinoidis triseriata) were used to evaluate how trophic positions and food web relationships have changed over time, using a study by Barry et al. (1996) as a comparison. Stomach-gut Content Analysis (SCA) was used to visually analyze the stomach contents and ten replicates per species of liver and white muscle tissue were analyzed for trophic position using Stable Isotope Analysis (SIA). Additionally, whole frozen prey items underwent SIA for trophic position to provide a basis for the food web. Comparing the results from SIA and SCA identified whether the elasmobranchs were benthic or pelagic feeders and what percentage of their diet is dependent on prey items available within Elkhorn Slough. The results will determine if and how trophic relationships are changing in a key estuarine habitat, and assist with management decisions and conservation of these elasmobranch species.

0296 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Robert Edman 1, Gorka Sancho 1, Bryan Frazier 2, John Kucklick 3, Walter Bubley 2
1 College of Charleston, Charleston, SC, USA, 2 South Carolina Department of Natural Resources, Charleston, SC, USA, 3National Institute of Standards and Technology, Charleston, SC, USA

Movement Patterns and Trophic Ecology of Tiger Sharks (Galeocerdo cuvier) Caught off the Southeast Coast of the United States

Exploitation of sharks has markedly increased in the past three decades, and this exploitation, coupled with degradation of essential habitats, can contribute to declining species abundance. Understanding the movement patterns and diet composition of sharks is central to creating and enacting appropriate management actions to preserve these animals and their habitats. Despite the large number of Tiger Sharks (Galeocerdo cuvier) in the western North Atlantic Ocean, the majority of research on Tiger Shark movement and diet has been concentrated in the Pacific and Indian Oceans. The present study seeks to fill these gaps of knowledge through analyses of the movement and diet of Tiger Sharks caught in coastal waters of the southeast United States. A multi-tag approach, utilizing passive acoustic telemetry and satellite telemetry, will provide insight into the movement patterns of Tiger Sharks both inshore along the coast and offshore throughout the Atlantic Ocean. Stable isotope analysis will be used to determine the trophic position of Tiger Sharks and estimate diet composition. Captured Tiger Sharks were sampled for skin, blood, and muscle to use in stable isotope analysis. Select sharks were surgically implanted with acoustic tags, and a number of these sharks were dual tagged with Smart Position or Temperature Transmitting (SPOT) tags as well. Preliminary data indicate that these Tiger Sharks repeatedly visit inshore areas but do not venture offshore of the continental shelf. Stable isotope analyses are ongoing and monitoring of tagged sharks will continue with additional sharks tagged and sampled this summer.

0149 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Dovi Kacev 1, Shannon Corrigan 3, Rebecca Lewison1, John Hyde 2
1 San Diego State University, San Diego, CA, USA, 2 Southwest Fisheries Science Center, La Jolla, CA, USA, 3 College of Charleston, Hollings Marine Lab, Charleston, SC, USA

Identifying Multiple Paternity in Two Species of Pelagic Shark

Polyandry is common throughout kingdom Animalia. There are several evolutionary explanations for the rise of this reproductive strategy including increasing genetic diversity, allowing for sperm competition as a proxy for male fitness, or high cost to females of mating avoidance. Several recent studies have found that multiple paternity is common among coastal and benthic shark species but to date, pelagic shark litters remain unstudied. Due to lower expected rates of conspecific interaction and higher opportunity costs, pelagic sharks may be less likely to have multiple matings than their coastal counterparts. In this study we opportunistically sampled single litters from shortfin mako (Isurus oxyrinchus) and common thresher (Alopius vulpinus) sharks (eight and four pups respectively). We used microsatellite markers to test for the possibility of multiple paternity in these species and discuss the possible implications. In the litters for both species, multiple paternity was detected. The mako litter was found to have at least two but more likely three sires, while the thresher litter has most likely two sires.

0430 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Katherine Vaccaro 1, Rebecca Varney 1, Dean Grubbs 2, Toby Daly-Engel 1

1 University of West Florida, Pensacola, FL, USA, 2 Florida State University, Tallahassee, FL, USA

Microsatellite Applications for Multiple Paternity in Squalus clarkae, a Novel Shark Species from the Gulf of Mexico

Squalus (Squalidae) is a genus of small, slow-growing sharks with long gestation periods. A new species, Squalus clarkae, was recently described from the Gulf of Mexico after being genetically and morphologically distinguished from Japanese Squalus mitsukurii. As a newly described species, little is known of S. clarkae's reproductive behavior. Thus far, multiple paternity in members of the genus Squalus has been understudied, and the degree to which shark species exhibit this behavior varies greatly. Eight species-specific microsatellite loci previously developed for congeners S. mitsukurii and S. acanthias and are being cross-amplified with S. clarkae to assess for their suitability in testing for paternity and kinship. These microsatellites will be applied to litters of S. clarkae to determine the presence and frequency of multiple paternity in this species using 13 litters with an average of 6.7 pups per litter. This study will offer the first genetic insight into the reproductive behavior of this species, and will provide life- history data necessary for future conservation efforts.

0014 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Hayley DeHart, Gavin Naylor
College of Charleston, Charleston, SC, USA

Comparing Demographic and Genetic Estimates of Population Sizes in Three Coastal Shark Species

Sharks are widely held by the scientific community to be threatened with extinction, and yet they remain some of the most poorly understood marine vertebrate organisms. There is belief among marine conservation biologists that population genetics based approaches can be used to distinguish species, populations, and even population sizes for these threatened animals. Estimating population sizes using multiple estimates, as well as multiple species, is critical to understanding true population sizes and life history traits that affect these estimates. This study aims to estimate census population size (Nc) and compare this demographic value to the genetically determined effective number of breeders (Nb). Census size will be estimated from an on-going demographic mark and recapture study conducted by South Carolina Department of Natural Resources and estimated using the program MARK. Effective number of breeders will be estimated using a cross-species gene capture method and variability will detected in these data to estimate effective number of breeders using the program NeEstimator. These methods will be deployed on three separate shark species: bonnetheads (Sphyrna tiburo), finetooth sharks (Carcharhinus isodon), and sandbar sharks (Carcharhinus plumbeus). These species all exhibit different population structure, life history, and recapture rates, which may in turn affect their Nb/Nc ratio, a value that may be used for future conservation regulation. It is believed that the comparisons between these estimates and species may be used for population assessment and management of coastal shark species.

0446 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Emily Peele
University of North Carolina at Wilmington, Wilmington, NC, USA

Genetic Diversity, Population Structure and Movements of the Bonnethead (Sphyrna tiburo) in North Carolina

The bonnethead shark (Sphyrna tiburo) inhabits coastal ecosystems and estuaries from North Carolina to Brazil. Some aspects of the genetic population structure of this species have been documented, including substantial variation between the Atlantic Ocean and Gulf of Mexico. S. tiburo that migrate to NC are primarily found in specific estuaries each year, yet genetic variances related to their site fidelity are unknown. This study will quantify genetic heterogeneity and detail population structure of bonnetheads along the NC coast. We are particularly interested in whether site fidelity reported previously for this species is associated with genetic population structure. Tagging efforts will help to reveal bonnethead migratory routes leaving NC estuaries and to identify overwintering grounds to the south. In conjunction with studying genetic differences, the mating system of this species will also be studied. Bonnetheads have been shown to exhibit a high percentage of genetic monogamy in Florida, contradictory to the expectation of polyandry seen in most shark species. Female specimens and their embryos collected as incidental bycatch from NC estuaries will be studied using microsatellite DNA profiling to determine numbers of males contributing to each litter. The oviducal gland will also be sampled for remaining sperm and profiled for number of paternal genotypes. Implications of this study include determining susceptibility of local populations to loss of genetic diversity in the event of population declines. Furthermore, a better understanding of the movement patterns of this highly migratory shark may lead to a reevaluation of conservation status.

0214 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Pavel Dimens, David Portnoy
Texas A&M University Corpus Christi, Corpus Christi, TX, USA

Structural Ambiguity: Population Demography of the Blacknose Shark in the Florida Keys

For marine species existing along seemingly continuous habitats, identifying regional groups poses challenges because it limits the ability to define a priori hypotheses with respect to population structure. Further, in species that feature large migrations, individuals from independent populations may co-occur seasonally on feeding grounds. A recent study using microsatellite markers identified five distinct populations spread across an area from South Carolina to the Yucatan and the Bahamas but found ambiguity in the Florida Keys, an area that spans the divide between the U.S. Atlantic and eastern Gulf of Mexico populations, as well as their management units. This study aims to use double-digest restriction associated DNA sequencing (ddRAD-seq) to identify single nucleotide polymorphisms (SNPs) and provide high-resolution population genetic data for blacknose shark in the Florida Keys. The goal is to distinguish between three possible scenarios of population structure and gene flow in the region: 1) the Keys are a zone of admixture between Atlantic and east Gulf of Mexico populations, 2) individuals from both populations are seasonally present in the keys but there is no gene flow, 3) the Keys are a unique population, separate from Atlantic and Gulf of Mexico populations.

0400 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Matthew Davis, Toby Daly-Engel
University of West Florida, Pensacola, FL, USA

Atlantic Sharpnose Shark (Rhizoprionodon terraenovae) Rangewide Genetic Stock Structure

The Atlantic Sharpnose shark is a small coastal species in the family Carcharhinidae that is common throughout the Gulf of Mexico and the Western Atlantic from Maine to Honduras. This species is regularly fished, representing as much as 45.9% of the artisanal elasmobranch fishery in the Gulf of Mexico. However, little is known about its population size, range, and movement patterns. We seek to delineate the stock structure and dispersal of this species using mixed marker molecular analysis. To date we have accumulated R. terraenovae tissue samples from a variety of locations in the Atlantic and northern Gulf of Mexico, and collections are ongoing. Connectivity will be assessed through statistical comparison of DNA sequences from both the mitochondrial and nuclear genome, including the control region and microsatellites. With these data we will delineate detailed patterns of gene flow and dispersal in R. terraenovae throughout its range, information that will enable managers and conservationists to better protect this species in the future.

0409 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015

Andrea Bernard 1, Cassandra Ruck 1, Vincent Richards 2, Jim Gelsleichter 3, Kevin Feldheim 4, Mahmood Shivji 1
1  Save Our Seas Shark Research Center, Nova Southeastern University, Dania Beach, FL, USA, 2 Clemson University, Clemson, SC, USA, 3 University of North Florida, Jacksonville, FL, USA, 4 Field Museum, Pritzker Laboratory for Molecular Systematics and Evolution, Chicago, IL, USA

The Genetic Connectivity of a Euryhaline Elasmobranch, the Atlantic Stingray (Dasyatis sabina)

Identifying the genetic connectivity of elasmobranchs inhabiting coastal waters remains an important global priority, as these species are particularly susceptible to human mediated impacts and declines given their close proximity to highly populated areas. The Atlantic stingray (Dasyatis sabina), a small, coastal species whose range spans the western North Atlantic (Florida to Chesapeake Bay) and Gulf of Mexico, is one of the few elasmobranchs capable of occupying both estuarine and freshwater habitats. Within Florida waters, a putative ‘resident’ population inhabits the freshwater St. Johns River System (SJRS); however, the extent of this population’s connectivity to the remainder of its distribution remains unknown. To examine the genetic connectivity of the Atlantic stingray across its southern US distribution, including the SJRS, a total of 312 individuals from 11 sampling locations were genotyped at nine species-specific microsatellite loci. Population- and individual-level analyses identified high levels of genetic population structure among collections, with coastal populations within the Gulf of Mexico showing high genetic structure (FST = 0.011 – 0.034; P <0.05) and a signal of isolation by distance (R2 = 0.957; P = 0.041). Interestingly, individual-based analyses showed that freshwater SJRS animals were differentiated from other locations, suggesting that these individuals may truly represent a ‘resident’ freshwater population. The presence of high genetic population structure, coupled with what may be locally adapted populations, suggests that care must be taken to conserve this species, as the extinction of even a single population may result in the irreversible loss of genetic diversity and adaptive potential.

0128 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Amanda Barker, John Gold, David Portnoy

Texas A&M University Corpus Christi, Corpus Christi, TX, USA

Identification, Stock Assessment, and Habitat Usage of Cryptic Hammerhead Sharks

The scalloped hammerhead (Sphyrna lewini) and the recently discovered Carolina hammerhead (Sphyrna gilberti) are cryptic species that are sympatrically distributed in the southeastern United States. Differing only in the number of precaudal vertebrae, scalloped and Carolina hammerheads are morphologically conserved; a way to distinguish them in situ has yet to be determined. Due to its recent discovery and lack of morphological differentiation Carolina hammerheads have likely been included in previous stock assessment for scalloped hammerheads, leading to an overestimation of scalloped hammerhead abundance. We will use double digest restriction-site associated DNA (ddRAD) sequencing to genotype individuals at thousands of single nucleotide polymorphisms (SNPs), and a panel of SNPs will be identified that can be used to reliably identify each species. Genetic and ecological data will be used to estimate relative abundance and habitat utilization of each species within known nurseries off the east coast of the United States. Because nursery utilization may not be equivalent between the species, one or more nurseries may be critical to one or both individual species persistence. For both species we will also generate estimates of baseline genetic diversity and conduct a preliminary assessment of stock structure to provide information useful for future species-specific management.

0238 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Jessica Jang, Catarina Pien, David Ebert

Moss Landing Marine Laboratories, Moss Landing, CA, USA

Unlocking the Mystery of Western Indian Ocean Electric Rays (Torpedinidae: Torpedo, Duméril 1806)

The Torpedinidae consists of two genera, Torpedo Duméril 1806, consisting of 15 species, and Tetronarce Gill 1862 that consists of 12 species. Torpedo species although morphologically similar, typically exhibits an ornate coloration, with distinct dorsal surface markings, and by the presence of spiracular papillae. Tetronarce species on the other hand are drably colored, and lack these distinctive papillae. As part of a broader investigation into the ecology, life history and taxonomy of southwestern Indian Ocean (SWIO) Chondrichthyans we are currently investigating the electric ray genus Torpedo. Three species are represented in the SWIO: Torpedo fuscomaculata, Peters 1855, Torpedo panthera, von Olfers 1831, and Torpedo sinuspersici, von Olfers 1831, but these may each involve species complexes given the striking color variation of specimens collected from different island groups within the region. Regional species each have distinctly different markings and patterning, orbital papillae/protrusions, and life history characteristics suggesting some of these island groups be home to regionally endemic electric rays. Here we present our findings to date on the mysterious electric rays of the SWIO.

0568 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Melissa C. Nehmens, David A. Ebert

Moss Landing Marine Laboratories, Pacific Shark Research Center, Moss Landing, CA, USA

Age and Growth of Deep-Sea Sharks on Seamounts in the Southwestern Indian Ocean

Knowledge of deep-sea Chondrichthyan life histories is relatively limited given the difficulties in obtaining adequate sample sizes. Life history characteristics that are known of deep-sea Chondrichthyans include slow growth, increased longevity, and late maturation. Ageing studies on deep-sea sharks, such as Squaliformes, are limited and necessitate further investigation as fisheries expand to deeper waters. During a series of surveys in the spring of 2012 and 2014 on the Madagascar Ridge in the Southwestern Indian Ocean, vertebrae and dorsal fin spines were collected from a suite of deep-sea sharks for age and growth analysis. The species collected were Centroscymnus coelolepis, C. owstoni, Centroselachus crepidater, Centrophorus granulosus, Dalatias licha, Deania calcea, D. profundum, Etmopterus granulosus, and Scymnodom plunketi. These species will be aged using their vertebrae and spines. This study will provide crucial information as part of a broader project to characterize the Chondrichthyan fauna on this remote chain of seamounts and may be useful in developing better management plans for this and other remote seamounts around the world.

0176 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015  
Jordan Taylor
College of Charleston, Charleston, SC, USA

The Chondrichthyan Fauna from the Upper Eocene, Upper Oligocene, and Lower Oligocene Formations in the Coastal Plain of South Carolina

The coastal plain in southeastern South Carolina is composed of the Eocene, Miocene, and Oligocene strata, which are characterized based on sedimentary deposits. These stratigraphic layers contain the isolated remains of Chondrichthyan teeth. While the stratigraphy of the coastal plain of South Carolina has been studied extensively, a detailed study of Chondrichthyan fauna distribution and abundance present in these strata has been neglected. Here, I intend to identify and report a detailed taxonomic study of the Chondrichthyan fauna and distribution using isolated teeth present in the southeastern formations in South Carolina. Teeth of identified Chondrichthyan fauna and the presence of other microfossils in these stratigraphical layers can suggest certain ecological niches, species diversity, and marine systems from these time periods. Not only is this study vital to understanding South Carolina marine history, it is also useful for recreational fossil collectors interested in properly identifying Chondrichthyan teeth.

0545 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Justin Cordova, David Ebert

Moss Landing Marine laboratories, Moss Landing, CA, USA

Species Grouping Within the Genus Apristurus Garman, 1913 Using Dermal Denticles

Apristurus is one of the largest shark genera, which encompasses 48 nominal species. Multiple morphological and molecular studies have shown the genus can be subdivided into three distinct subgroups: the A. brunneus subgroup, A. spongiceps subgroup, and A. longicephalus subgroup. This study examines the dermal denticles of three Apristurus species, one representative of each subgroup; specimens were collected off the coast of Monterey Bay CA, and Tai-chi, Taiwan. The three-species used for this study includes A. kampae for the spongiceps group; A. brunneus for the brunneus group; A. herklotsi for the longicephalus group. Dermal denticles were taken from four different locations on the specimens and observed under a dissecting microscope. Morphological features including cuspid counts, denticle size, and spacings are compared in order to find any noticeable differences. Observations reveal that the denticles of A. kampae are widely spaced and have a unicuspid structure, where the other specimens exhibited a tricuspid structure with overlapping denticles. These differences will be further examined as a means of further organizing the genus taxonomically, and to investigate whether these differences may have ecomorphological significance relative to their preferred associated habitats.

0303 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Daniel Huber 1, Bethany Loya 1, Summer Decker 2, Jonathan Ford 2

1 The University of Tampa, Tampa, FL, USA, 2 University of South Florida, Tampa, FL, USA

Structural Mechanics of Sixgill and Mako Shark Jaws: Evolutionary Considerations

Jaw morphology has changed dramatically over the course of shark evolutionary history, and this diversity of morphology has been postulated to reflect variability in feeding mechanism, behavior, and ecology. The purposes of this study were to 1) compare the structural mechanics of the jaws of the bluntnose sixgill shark Hexanchus griseus and longfin mako shark Isurus paucus, which approximate relatively ancestral and derived jaw morphologies respectively, and 2) investigate the mechanical consequences of the transition from bone to cartilaginous jaws, which occurred early in the evolutionary history of chondrichthyan fishes. Jaws were CT scanned, segmented, and modeled to represent various character states of skeletal composition (unmineralized cartilage, composite mineralized/unmineralized cartilage, bone). Stress, strain, and strain energy density were determined using finite element analysis. Isurus paucus exhibited comparable stress, but less strain and strain energy density than H. griseus, indicating that the material and morphology of jaws have become more efficient at handling stress and strain. The heterogeneous model (composite mineralized, unmineralized cartilage) resulted in low stress, intermediate strain, and intermediate strain energy density for all jaws. These results suggest that shark jaws may have been structurally modified over time to better resist stress and strain by virtue of changes in their geometry and that emergent mechanical properties derive from the combination of mineralized and unmineralized cartilage.


0557 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Csilla Ari 1, 2, 3, Dominic D`Agostino 1

1 University of South Florida, FL, USA, 2 Foundation for Oceans of the Future, Budapest, Hungary, 3 Manta Pacific Research Foundation, HI, USA

Melanosome Aggregations Might Cause Manta Ray Skin Change Color

Natural body coloration and spot markings of giant manta rays are used to identify individuals and to distinguish species. However, recent observations revealed rapid and long-term coloration changes of giant manta rays, suggesting that their body pigmentation is not permanent over their lifespan as assumed before. The rapid coloration changes happened within a few minutes, while such rapid changes were not described in other elasmobranch species yet. In order to reveal the mechanism of these changes, histological studies were performed on giant manta ray skin. The results suggest that changes of the degree of melanophore and melanosome aggregations might contribute to coloration changes in the manta ray skin. Further studies are needed to determine what regulates the changes in melanosome aggregations and to understand the role of such changes in giant manta rays.

0125 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Bianca Prohaska, R. Dean Grubbs

Florida State University, Tallahassee, FL, USA

Stress Physiology of Deep Demersal Sharks in the Gulf of Mexico

Prior to the Deep Water Horizon oil spill, little research effort was focused on studying the physiology of deep demersal sharks inhabiting the Gulf of Mexico. While the physiology of these fishes remains virtually unknown, they are still routinely captured in commercial fisheries, both as targeted catch and as bycatch. In the absence of basic biological data, effective management plans cannot be formulated, making populations highly susceptible to declines. Potential effects the oil spill has had and will continue to have on these organisms are also unknown. Blood chemistry analysis can be used as a method of assessing physiological stress in elasmobranchs, and using this method three main questions will be addressed in the present study: 1) What are the baseline blood chemical parameters in deep demersal elasmobranchs? 2) Are the stress responses in these species ecologically-mediated or taxonomically-mediated? 3) Are there significant differences in blood chemical profiles between elasmobranchs potentially affected by the oil spill and those captured in less affected areas? Preliminary results suggest that stress responses are relatively similar among seven elasmobranch species sampled thus far, including Mustelus sinusmexicanis, M. canis, Squalus cubensis, S. c.f. mitsukurii, Centrophorous c.f. uyato, C. granulosus, and Hexanchus griseus. However, lactate and pCO2 concentrations in M. sinusmexicanis, M. canis, and S. cubensis are relatively higher than that of the other species sampled, potentially suggesting a depth mediated stress response.

0423 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Samantha Ehnert, Jim Gelsleichter

University of North Florida, Jacksonville, FL, USA

Mercury Accumulation and Effects in the Brain of Atlantic Sharpnose Sharks (Rhizoprionodon terraenovae)

Studies have shown that sharks often bio-accumulate mercury concentrations that threaten the health of human consumers. However, few studies have examined mercury in the central nervous system of sharks or how mercury affects shark neurophysiology. This study's goal is to determine if elevated levels of mercury often found in shark muscle also occur in the brain, and if mercury accumulation is associated with damage to the shark's nervous system. Muscle and brain mercury concentrations in the Atlantic sharpnose shark (Rhizoprionodon terraenovae) are being measured and compared. Brain mercury concentrations with S100b concentrations, bioindicator of mercury-induced neurodegeneration, in shark cerebrospinal fluid (CSF) are being compared. Sharks were collected along the U.S. Southeastern coast. Total mercury concentrations in dried muscle and brain samples were measured using a Direct Mercury Analyzer. Levels of S100b were measured in shark CSF using an ELISA. Preliminary results show strong correlations between mercury in the muscle and brain. Brain mercury levels were significantly lower than the muscle and most known thresholds for biological effects; suggesting limited potential for neurological impacts. Data on S100b concentrations in CSF support this premise, as increased brain mercury levels were not correlated with increased S100b, suggesting mercury levels are below the threshold needed for release of S100b as a function of neurotoxicity. Measurements of oxidative stress, another marker of mercury-induced neurotoxicity, are being analyzed. This study will be one of the first to examine the direct impacts of mercury uptake in sharks, and therefore contribute significantly to the field of shark ecotoxicology.

0405 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Jillian Sawyna, Kelly Radecki, Weston Spivia, Marika Gotschall, Deborah Fraser, Christopher Lowe

California State University, Long Beach, Long Beach, CA, USA

Establishing Baseline Parameters for Assessment of Immunological Effects of Organochlorine Exposure in Elasmobranchs

To evaluate the effects of chronic organochlorine (OC) exposure on elasmobranch immunity, a baseline of immunological parameters including complete blood counts, leukocyte counts, and phagocytosis was established. Round stingrays (Urobatis halleri) were collected from Santa Catalina Island, CA, which is considered a low contamination reference site for toxicology research off California. The genetically isolated population of rays from Catalina exhibit a low mean summed OC tissue concentration of 0.90 Ī 0.98 ng/standardized liver sample compared to the mainland population, 15.7 Ī 11 ng/standardized liver sample. Leukocytes obtained from lymphomyeloid tissues and peripheral blood were assayed for phagocytic activity in vitro. Using flow cytometry, % phagocytosis and phagocytic activity were evaluated by assessing % leukocytes positive for, and relative amounts of ingested fluorescent E. coli BioParticles. Cells isolated from splenic tissue, had a higher percentage of phagocytes in the sample cell population, with a mean % (ĪSE) phagocytosis of 18.85 Ī 4.59, compared to peripheral blood, 8.58 Ī 1.53, and epigonal tissue, 13.11 Ī 4.93. Blood demonstrated a higher measure of the phagocytes’ activities, with a mean fluorescence intensity (ĪSE) of 2244.90 Ī 265.63, whereas cells isolated from spleen and epigonal were calculated as 1568.65 Ī 211.87 and 796.15 Ī 174.27, respectively. Using microscopy, the same trend in % phagocytosis was found, but percentage values were higher, suggesting flow cytometry was a more conservative approach. These values can now be compared to those from the heavily OC contaminated southern California coastal mainland to determine if immunosuppression is correlated with OC exposure.


0404 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Kady Lyons 1, Douglas H. Adams 2
1 University of Calgary, Calgary, Alberta, Canada, 2 Florida Fish and Wildlife Conservation Commission, Melbourne, FL, USA

Maternal Offloading of Organochlorine Contaminants in the Pseudoplacental Scalloped Hammerhead

Elasmobranchs have a propensity to accumulate high contaminant levels, especially in species that occupy upper trophic levels. However, contaminant concentrations and the types of contaminants that marine fishes accumulate can vary with species, age, sex and environmental parameters. In addition, females have the ability to transfer contaminant to their young through reproductive processes. Therefore, contaminant concentrations and signatures can be used a tool for examining elasmobranch ecology. Organic contaminants (PCBs and chlorinated pesticides) were measured in livers of both female and male scalloped hammerheads (Sphyrna lewini) from several age classes that were collected from U.S. Atlantic waters, including two near-term pregnant females and their embryos. Adult female hammerheads were found to have lower levels of PCBs compared to the younger, adult male (mean Ī SD, 11.1 Ī 1.0 versus 22.8 μg g-1 lw), but had substantially higher concentrations of pesticides (4.1 Ī 0.9 versus 1.9 μg g-1 lw). While females were found to offload substantial contaminants to their offspring, females were only able to depurate their total hepatic load by approximately 0.03 to 2.3%. Differences in standardized contaminant concentrations were observed between the adult male and females, with males having greater proportions of more chlorinated PCB congeners. These differences could be due to the ability of females to offload contaminants to offspring as well as sexual segregation in habitat use. Results from future contaminant studies with increased sample sizes from different localities will further our understanding of scalloped hammerhead health and ecology and aid in effective conservation.

0249 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Sarah Hoffmann, Steven Warren, Andrea Hernandez, Marianne Porter
Florida Atlantic University, Boca Raton, FL, USA

Swimming Kinematics of Juvenile Sphyrna lewini

Hammerhead sharks (Sphyrnidae) have a unique, dorso-ventrally compressed head that may act as a hydrofoil, generating lift and increasing maneuverability in the horizontal plane during swimming. Previously, researchers hypothesized that the cephalofoil acts as a stabilizer during swimming to maintain the shark’s position parallel to the substrate. This is different than more streamlined sharks, which use whole body rolling during swimming. Furthermore, hammerheads have greater hypaxial musculature allowing for a larger range of motion of the head. As a result, a slight change in the angle of attack of the cephalofoil could produce a significant change in pitch angle of the shark with limited energy expenditure. Our goal is to examine the whole-body swimming kinematics of juvenile scalloped hammerhead sharks, Sphyrna lewini, to better understand how head morphology has shaped swimming performance. From previous kinematics data on lift generation in elasmobranchs, we predict that the cephalofoil is generating lift. Kinematic data was assessed using synched dorsal and lateral video of S. lewini. We measured volitional straight swimming performance variables by tracking the movements of anatomical landmarks through time. These landmarks included points on the body midline, cephalofoil, pectoral fins, and caudal fin. The movements of these points were correlated with performance variables such as whole body velocity, body curvature, tailbeat frequency, tailbeat amplitude, head yaw, and cephalofoil and pectoral fin angles of attack. From these data, we are able to quantify swimming performance and better understand how the cephalofoil of hammerhead sharks may be increasing maneuverability and generating lift.

0024 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
John Whalen, Jim Gelsleichter

University of North Florida, Jacksonville, FL, USA

Multibiomarker Evaluation of Pollutant Effects in Atlantic Stingray (Dasyatis sabina) Populations in Florida's St. Johns River

The goal of this study was to examine the potential health effects of polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbon (PAH) exposure on Atlantic stingray (Dasyatis sabina) populations in Florida's St. Johns River (SJR). Special emphasis was placed on identifying PAH- and/or PCB-related effects in stingrays from areas of the lower SJR basin that have been shown to possess elevated levels of these compounds, as well as characterizing baseline levels of pollutant exposure in other areas that may be subjected to dredging in the near future, potentially resuspending contaminated sediments and increasing pollutant associated effects. To accomplish this, we measured PCB and PAH biomarker levels in D. sabina collected from contaminated sites and reference locations. Animals were collected using seine nets and trotlines. We specifically examined the biomarkers cytochrome P4501a1 (CYP1a1), a Phase I detoxification enzyme; Glutathione-S-Transferase (GST), a Phase II detoxification enzyme; and fluorescent aromatic compounds (FACs), PAH bile metabolites. Enzymatic activity of CYP1a1 and GST was measured using the EROD assay and a commercially available GST Assay Kit, whereas FACs were measured using fixed wavelength fluorescence. Biomarker levels of individuals collected from contaminated sites were compared to individuals collected from reference sites. Previous research in our lab has detected elevated biomarker levels in D. sabina and bony fish from known contaminated areas in the St. Johns River. Expecting parallel results, we anticipate that the pollutants in the St. Johns River are negatively affecting D. sabina, and that dredging has the possibility to create a broader source of contamination.

0588 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Catarina Pien, David Ebert, Jessica Jang, Paul Clerkin, Justin Cordova, Matthew Jew, Breanna Machuca, Melissa Nehmens, Amber Reichert, Victoria Vasquez, Kristin Walovich
Moss Landing Marine Laboratories, Moss Landing, CA, USA

Looking for "Lost Sharks"

Sharks, and their relatives the batoids and chimaeras, come in a variety of sizes and shapes, from the whale shark (Rhincodon typus), the world's largest fish, to the dwarf pygmy sharks (Squaliolus spp.), and occupy most marine, and some freshwater, habitats. There are more than 500 species of sharks, along with nearly 650 batoid and 50 chimaera species, bringing the overall total to about 1200 species of sharks and shark-like fishes. The diversity of sharks and their relatives has increased exponentially over the past decade with more than 230 new species having been described over the past decade. This represents nearly 20% of all shark species that have been described. Most of these new discoveries have come from the Indo-Australian region, followed by the western Indian Ocean and western North Pacific regions. However, a review of the Red List status of Chondrichthyans indicates that 17.4% are threatened and nearly half (46.8%) are Data Deficient or have not been assessed. Despite such a rich and diverse fauna, the majority of sharks and their relatives have largely been "lost", having been overshadowed by a few large charismatic media mega-stars, such the Great White Shark (Carcharodon carcharias). In an effort to highlight and assess these little known, or unknown, species we have initiated a global program "Looking for Lost Sharks" to find and discover these lost sharks.

0299 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Liz Vinyard 1, Walter Bubley 2, Bryan Frazier 2

1 University of Charleston, South Carolina, Charleston, SC, USA, 2 South Carolina Department of Natural Resources, Charleston, SC, USA

Age, Growth, and Maturation of the Finetooth Shark, Carcharhinus isodon, in Coastal Waters of the Western North Atlantic Ocean

Age, growth, and maturation are crucial fishery dynamics to understand, as they provide vital information that can be used for stock assessments of fishes. Because ontogenetic changes occur across the life history of many marine organisms, including elasmobranchs, an effort should be made to obtain specimens across entire size ranges for both sexes to accurately represent a given population structure. This study proposes three main objectives: 1) examine size at age while validating seasonal periodicity of increment formation used in age estimation, 2) estimate size and age of sexual maturation and 3) compare growth models to published growth models from the western North Atlantic and Gulf of Mexico. Samples will be collected from April 2014 through October 2015 from estuaries and nearshore waters off of South Carolina. Additional vertebral samples from a 2003 study and ongoing sampling with South Carolina Department of Natural Resources (SCDNR) will increase the sample size to approximately 500 vertebrae. Results of this study will provide accurate information regarding growth and maturation for the Finetooth Shark population along the southeastern United States.

0471 Poster Session I, AES CARRIER AWARD, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Kristin A. Walovich, David A. Ebert
Moss Landing Marine Laboratories, Pacific Shark Research Center, Moss Landing, CA, USA

‘SPOT A BASKING SHARK’: How Citizen Scientists Can Help Save an Enigmatic Shark

The distribution and trans-equatorial migrations of the basking shark (Cetorhinus maximus) have been well documented in the Northern Atlantic, yet seasonal patterns of distribution have not been fully elucidated in the eastern North Pacific. Filling in vital knowledge gaps will help inform the best recovery plan to rebuild the basking shark population in this region, which has been designated a ‘Species of Concern’ by NOAA’s National Marine Fisheries Service and ‘Endangered’ by the International Union for the Conservation of Nature (IUCN). The ‘Spot a Basking Shark’ Project, ongoing since 2010, is a collaborative effort to investigate the abundance, distribution, and population status of basking sharks in the eastern North Pacific. The project employs a web-based reporting system for the public to record sightings, utilizes satellite tags to improve understanding of essential habitat and geographic range, and obtains additional information on life history and patterns of occurrence by data–mining existing records. Have you seen a basking shark? Report your sighting on our website: http://psrc.mlml.calstate.edu/current-research/basking-shark/

0080 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Simon Dedman 1, Rick Officer 1, Deirdre Brophy 1, Maurice Clarke 2, David Reid 2
1 Galway-Mayo Institute of Technology, Galway, Co. Galway, Ireland, 2 Marine Institute, Rinville, Co. Galway, Ireland

Modelling Abundance Hotspots for Data-poor Irish Sea Rays

Skates and rays represent one of the most vulnerable components of the fish community in temperate demersal fisheries such as the Irish Sea. They also tend to be data-poor in comparison to commercially exploited teleost fish. Spatial management has been suggested as an important tool in protecting these species, but requires an understanding of the abundance distribution, and its relationship with the environment at both adult and juvenile life history stages. In this analysis, delta log-normal boosted regression tree models were used with bottom trawl survey data to derive rays' spatial abundance, and environmental links. The modelling approach allowed the development of detailed predictive maps of abundance of four common and rare skate and ray species implicated in the fishery: thornback, spotted, cuckoo and blonde rays. The distributions were driven by a general preference for sand and courser substrates, higher salinities, temperatures and currents speeds. The abundance distribution maps were examined together with maps of skate and ray commercial landings, suggesting that the main hotspots for the species were away from the main commercial fishing areas. The maps were also compared to potential MPAs proposed for wider ecosystem protection, and the main hotspots were well covered by the proposed MPAs. This combination of the main abundance hotspots in areas of low fishing, and wider potential ecosystem protection, suggests good potential for spatial management measures to protect these species in the Irish Sea.

0256 Poster Session I, Reno Ballroom & Tahoe Room, Friday 17 July 2015
Hua Hsun Hsu 1, David A. Ebert 2, Shoou Jeng Joung 1, Kwang Ming Liu 1, Chia Yen Lin 1

1 National Taiwan Ocean University, Keelung City, Taiwan, 2 Moss Landing Marine Laboratories, Moss Landing, CA, USA

Catch and Preliminary Fishery Biological Information of Megamouth Sharks Megachasma pelagios in Eastern Waters off Taiwan

Megamouth shark Megachasma pelagios is rare and one of three filter-feeding shark species. Prior to this study, only 65 megamouth sharks have been recorded during 1976- 2015; 6 from the Atlantic Ocean, 6 from the Indian Ocean, and 53 individuals from the Pacific Ocean. In fact, an additional 32 megamouth sharks were caught by gill nets off Hualien, eastern Taiwan between 2013 and 2014. All sharks were caught at night before dawn from April to August, with most of them caught with ocean sunfish (Molidae), the primary target species of drift net fishery. Of the 32 specimens, body weights (BW) ranged from 210-1147 kg, and lengths measured from 220-560 cm in precaudal length, 250-710 cm in total length (TL); sexes were 20 females (250-710 cm TL), 11 males (363-484 cm TL), and sex was unknown for one individual (500 cm TL). Reproductive condition was determined for 17 sharks, two females were determined to be mature, 11 (5 females 6 males) were maturing, and 4 other females were immature. Stomach contents of 12 individuals examined, indicated that 5 were vacuous, 6 were with partial prey, and 1 was full of prey. Parasites were collected from pectoral fins, mouth, gill slits, stomach, and intestine of 14 individuals. The BW-TL relationships were estimated to be BW=2.316 TL - 524.06 (r2=0.72, n=11) for male, and BW =0.198 TL1.286 (r2=0.42, n=20) for female, respectively. Eastern waters of Taiwan may be a very important feeding ground for juvenile and subadult megamouth sharks.
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AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015 Morning & Afternoon (1/2 h talks)

0476 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
E.W.
Misty Paig-Tran 1, Lara Ferry 2
1 CSU Fullerton, Fullerton, CA, USA, 2 Arizona State University West, Phoenix, AZ, USA

Integrative Elasmobranch Biology for the 21st Century

The current climate at granting institutions requires new research proposals to be truly interdisciplinary between two or more fields to be competitive for funding. NSF now has an entire division (Integrative Organismal Systems) dedicated to supporting research that is inherently integrative and asks us to identify "Grand Challenges in Organismal Biology". We argue in this symposium that elasmobranchs are excellent candidates for integrative research for numerous reasons, the most compelling of which are that: 1) they are ideal for asking large scale evolutionary questions (ex. evolution of endothermy) as they are a basal vertebrate on the tree of life and have survived with essentially the same features as they had 450 million years ago; 2) they are ecologically unusual in that they are the apex predators in nearly every system where they are present and thus play an important and possibly unmatched role in most trophic systems; and, 3) they are functionally important in that they possess an entirely cartilaginous skeleton, they are the first lineage to develop a true set of jaws, and they have the complex sensory system we typically associate with all vertebrates. Here we present a review of the history of integrative elasmobranch research and touch upon how the future of elasmobranch research is driving a variety of scientific fields of study highlighting how elasmobranchs were an essential part of the research, that elasmobranchs were the ideal organism for the research, and how the research is truly interdisciplinary between two or more fields of study.

0102 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
Lisa B. Whitenack 1, Matthew Kolmann 2

1 Allegheny College, Meadville, PA, USA, 2 University of Toronto, Toronto, Ontario, Canada

Integrative Chondrichthyan Paleobiology: The Present is the Key to the Past

The chondrichthyan fossil record is composed primarily of teeth, though occasionally other body parts are preserved. This often translates into using fossils for studying taxonomy, biostratigraphy, paleoecology, and evolutionary history. Studies that integrate across disciplines are few, and those that do tend to utilize extant taxa. We will discuss those studies that have used integrative techniques, focusing on the use of fossil teeth to understand chondrichthyan evolution in a broad sense. We then will examine trends in tooth morphology coincident with trends in prey availability across geological time. Finally, we will identify holes in our knowledge of chondrichthyan evolution and look forward to how integrative techniques can help us explore this topic.

0018 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
Ronald Seidel 1, David Knoetel 2, Merlind Schotte 2, Daniel Baum 2, Daniel Huber 3, Michael Blumer 4, James Weaver 5, Mason Dean 1

1 Max Planck Institute, Potsdam, Germany, 2 Zuse Institute, Berlin, Germany, 3 University of Tampa, Tampa, FL, USA, 4 Medizinische Universitaet, Innsbruck, Austria, 5 Wyss Institute for Biologically Inspired Engineering, Cambridge, MA, USA

Interdisciplinary Approaches to Skeletal Biology and Mechanics: Design Lessons from Shark Skeletons

Fish skeletal tissues are far more diverse than those of mammals, providing unique windows into skeletal biology, development and form-function relationships in general, but also the evolutionary and environmental pressures that shape anatomy. We investigate the materials, structure and mechanics of elasmobranch cartilage, comprised of unmineralized cartilage wrapped in a layer of geometric, sub-millimeter, mineralized tiles (tesserae). Our interdisciplinary collaboration ties together high-resolution material and ultrastructure data with analyses of skeletal form to build bio-realistic and bio- inspired 3d-printed models for hypothesis testing and comparison with native tissues. We’ve learned that tesserae begin from isolated mineralization zones, employing a similar mineralization regulation pathway to bone, but being patterned on a wider diversity of collagens. As tesserae grow into contact, striking patterns of structural reinforcement appear, developing mineral density and tissue stiffness comparable to (and sometimes higher than) mammalian mineralized cartilage or bone. Using custom, quantitative shape analyses of high-resolution CT scans, we map the massive network of tesserae on skeletal elements, allowing derivation of tissue growth and tiling laws and comparison with theoretical tilings. These data act as inputs into physical and theoretical models of tessellated cartilage, developed using new multi-material 3D printing techniques for high-resolution model fabrication. Combined with quantitative shape and mechanics analyses of whole jaws from shark species with different diets, we draw together multiple size scales to build holistic understandings of skeletal biology, learning fundamental design rules for this and other skeletal tissues, as well as layered, low-density composite materials in general.

0178 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
Brooke Flammang
New Jersey Institute of Technology, Newark, NJ, USA

Biomechanics of Shark Swimming

The mechanics of the heterocercal tail in sharks is a classic problem in functional vertebrate biology. Because sharks lack a buoyant swim bladder, their ability to produce lift and balance torques while swimming has long been a subject of research and debate in the field of vertebrate locomotion. Just as understanding the kinematic motions of the shark tail required three-dimensional analysis, new three-dimensional fluid dynamics tools allow us to view complex swimming instantaneously without trying to assimilate data from multiple two-dimensional data sets. Recently, I have discovered not only how sharks are able to produce lift, but also how they are able to modulate their tail stiffness to generate nearly continuous thrust.

0427 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015Christine Bedore 1, Nicholas Wegner 2
1 Georgia Southern University, Statesboro, GA, USA, 2 Southwest Fisheries Science Center, National Marine Fisheries Service, La Jolla, CA, USA

Sensory Ecology of Elasmobranch Fishes

The sensory systems of chondrichthyan fishes are thought to represent the basal vertebrate condition from which more advanced modalities arose. Additionally, elasmobranch fishes inhabit nearly every marine environment and correspondingly represent a wide range of ecological adaptations. Therefore, elasmobranchs demonstrate an impressive array of sensory adaptations that correspond to their individual niches and provide ideal subjects for studying sensory adaptation to biological and physical environments. For example, most batoids possess duplex retinae comprised of rod and cone photoreceptors, although the potential for a species to have color vision varies with the spectral composition of the habitat. Cownose rays, Rhinoptera bonasus, have two cone pigments with color sensitivity that corresponds to their turbid, green-dominated, estuarine habitat. Similarly, yellow stingrays, Urobatis jamaicensis, have three cone pigments that correlate to their inhabitance in clear, spectrally rich reef-associated waters. Additionally, differences in visual temporal resolution, the ability to track moving objects, differs between these two species with the active, schooling cownose rays suffering a lower reduction in temporal resolution with decreases in ambient light levels and temperature. The reduced thermal sensitivity, combined with possession of a cranial rete, suggests that cownose rays may use cranial endothermy, or “brain warming”, to minimize reductions in nervous and sensory function when challenged with environmental temperature changes. Due to their small size relative to most cranial endotherms, as well as their ease of collection and maintenance in the laboratory, cownose rays make ideal models for testing unresolved hypotheses regarding sensory- driven evolution of cranial endothermy in fishes.

0500 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
Nicholas Wegner

NOAA Fisheries, La Jolla, CA, USA

The Elasmobranch Gill: A Window into Evolution and Physiology

Due to its multiple functions in respiration, osmoregulation, pH balance, and nitrogenous waste excretion, many comparative physiologists consider the fish gill one of the most complex animal organs. Although the functional unit of the fish gill (the gill filament) has remained structurally and functionally intact throughout the course of fish evolution and diversification from lampreys to teleosts, the elasmobranch gill has a number of largely unique features. Perhaps most notably is the connection of the gill filaments to interbranchial septa, which affects not only the flow of water through the gills, but may provide specific advantages and disadvantages to elasmobranch respiration. Thus, in many ways, the elasmobranch gill provides unique insight into the evolutionary factors that sculpt gill morphology and function. Because many elasmobranchs (and other fish groups) are large, live in remote or inaccessible habitats, and or have high activity levels, direct physiological studies conducted in the laboratory or under controlled conditions may not be feasible. For such groups, examination of branchial morphology can provide significant insight into metabolic requirements and other important aspects of a species physiology.

0031 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
Yannis Papastamatiou

University of St Andrews, St Andrews, UK

A Day in the Life: Combining Biologging and Modelling to Understand Shark Behaviour and Physiology

Sharks represent an important ecological group as many species are meso or upper level predators. They are also an excellent study animal for ecological and behavioural

studies as their larger size allows them to retain and carry a variety of sensors that record behavioural and physiological data in real time. With the current iterations of sensors we can measure the horizontal and vertical movements, activity, habitat selection, digestive physiology, and biomechanics of free-ranging animals. However, these tools are producing large datasets, and we need the appropriate statistical and modelling tools to appropriately analyse them. Analytical tools such as Hidden Markov Models allow us to identify switching behaviours and determine the covariates that drive these switches, and can be applied to a variety of time-series data including animal step lengths and turning angles, swimming depths, and activity. I will illustrate these methods using tracking data from white sharks, and behavioural/physiological data from reef (grey reef and blacktip reef sharks) and pelagic (oceanic whitetips) sharks. By combining these methods we can start to move beyond just describing shark movements, but also focus on the drivers of these movements.

0462 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015 
Heather Marshall 1, Diego Bernal 2, Gregory Skomal 3, Richard Brill 4, Peter Bushnell 5, Nick Whitney 1

1 Mote Marine Laboratory, Sarasota, FL, USA, 2 University of Massachusetts Dartmouth, North Dartmouth, MA, USA, 3 Massachusetts Division of Marine Fisheries, New Bedford, MA, USA, 4 National Marine Fisheries Service, NOAA, Gloucester Point, VA, USA, 5 Indiana University South Bend, South Bend, IN, USA

The Importance of Physiology in Shark Mortality Assessments and Fisheries Management

The National Marine Fisheries Service recently released the Atlantic Highly Migratory Species Management-Based Research Needs and Priorities, with research needs including establishing post-release mortality rates for commercially caught sharks. Published at-vessel mortality rates indicate that capture-associated mortality is species- specific. Through assessments using various types of electronic tags (e.g., pop-up satellite archiving tags and accelerometer tags), such species-specific responses appear to carry over to post-release mortality rates as well, with rates ranging from 0% (Galeocerdo cuvier, and Carcharhinus leucas) to 75% (C. brevipinna). Research assessing interspecific mortality rates is critical, but it is also imperative to understand the physiology underlying such mortality events. The physiological upset sharks experience while captured on fishing gear can result in irreversible cellular damage, resulting in immediate or delayed mortality. Previous research on shark stress physiology has found that changes in various blood stress indicators (e.g., lactate) are correlated with magnitude of the capture stress, and that blood potassium levels are significant (p<0.05) predictors of both at-vessel and post-release mortality. The future of such research lies in pointed physiological studies to understand how stress indicators and mortality are linked, and how such information can be used to understand the capture-related stress response in teleosts as well. The further elucidation of mortality indicators, and what is driving such mortality events, can be used on various scales in the future to predict mortality rates, and develop mitigation measures for fisheries management.

0402 AES Integrative Elasmobranch Biology Symposium, Carson 2, Saturday 18 July 2015
Kady Lyons, Matt Vijayan
University of Calgary, Calgary, Alberta, Canada

Compromised Stress Response in Round Stingrays Exposed to PCBs along the Southern California Coast

Stress response impairment due to environmental contaminant exposure has been documented in a variety of organisms; however, little research has investigated these types of effects in elasmobranch fishes. The objective of this study was to examine the primary and secondary stress response in round stingrays (Urobatis halleri) that have been exposed to different levels of environmental organochlorine contaminants, primarily polychlorinated biphenyls (PCBs). Our hypothesis was that higher PCBs body burden would compromise the stress response in this species. To test this, stingrays were sampled from two locations (mainland California, Long Beach, and a nearby offshore island, Catalina) and subjected to two treatments (“stressed” and “unstressed”). Stingrays were collected by hook and line from these two locations and plasma was sampled either immediately (unstressed) or 15 min after handling and confinement (stressed) to examine changes in liver and plasma parameters. Stingrays sampled from Long Beach had significantly higher hepatic PCB levels compared to stingrays Catalina. Our results support the hypothesis that higher PCB body burden suppresses the highly conserved corticosteroid stress response in these animals. Also, liver glucose and glycogen content were lower in the stressed Long Beach stingrays compared to the Catalina rays. Overall, PCB contamination reduces the capacity to elicit a physiological stress response in the round stingrays.
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AES Morphology & Physiology, Carson 2, Sunday 19 July 2015 Morning

0440 AES Morphology & Physiology, Carson 2, Sunday 19 July 2015
Carl Luer 1, Cathy Walsh 1, Laura Edsberg 2, Jennifer Wyffels 2
1 Mote Marine Laboratory, Sarasota, FL, USA, 2 Daemen College Center for Wound Healing Research, Amherst, NY, USA

Experimental Wounding of Atlantic Stingrays, Dasyatis sabina: Role of Epidermal Mucus in Protection of Early Stage Wound Beds

Anecdotal reports of relatively rapid and infection-free healing of wounds in sharks and rays are common, yet controlled experimental wounding studies to characterize the healing process are rare. Experimental wounds were inflicted on pectoral fins of Atlantic stingrays, Dasyatis sabina, by excising the epidermal and dermal layers of skin and exposing the epaxial musculature. While the gross physical appearance suggests that wound beds are covered by blood and/or blood clots for at least the first 4 days, histology has shown that migration of epidermal cells from the wound margin onto the bed is well underway by 16-24 hours. By 48 hours, the wound bed is completely covered with a thin epidermal layer containing mucus cells and a clearly identifiable basal layer. Wound biopsy samples were examined using scanning electron microscopy (SEM) and post-fixation to preserve secreted epidermal mucus. Resulting SEM images of 8, 16, and 24 hour wounds demonstrate that wounds are covered with mucus before re- epithelialization. The 24 and 16 hour wound beds are obscured almost completely by mucus, while much of the 8 hour wound bed surface, particularly near the wound bed margins, is also covered by mucus. Studies are underway to investigate the extent of mucus coverage on wounds at times earlier than 8 hours. Epidermal mucus secretions isolate the wound from the environment and may represent the first line of defense for wound healing in D. sabina.

0560 AES Morphology & Physiology, Carson 2, Sunday 19 July 2015
Michael Doane, Elizabeth Dinsdale

San Diego State University, San Diego, CA, USA

Revealing a Physiological Role of Shark Skin Through Microbial Community Analysis

Sharks are apex predators that support an unnoticed yet diverse consortia of microbial organisms. Microbial life is inherently involved in the health of sharks but little is known of baseline composition of the shark microbiota. Shark skin is the first line of defense against pathogenic environmental microbiota. We hypothesized the boundary layer would yield structured microbial communities that were distinct from the water column microbiota. Microbes were collected from the base of the first dorsal fin of 6 Common thresher sharks (Alopias vulpinus) in the California Bight using a “supersucker” method. DNA was processed for shot-gun metagenomics and sequenced using Ion Torrent technology. The MG-RAST platform was used to annotate the resulting genomic data, which yielded an average of 936,614 high quality sequences having an average sequence length of 180 base-pairs. Each metagenome yielded an average of 577,797 sequences with protein coding motifs but of those only 2.9 to 8.2% matched known protein sequences in the SEED database. Microbial communities were more similar within shark samples than the water column microbial communities (PERMANOVA, p=0.003). Potential functional composition of microbial communities was also more similar to other shark samples than to the water column (PERMANOVA, p<0.001). Highly structured, distinct microbial communities on the skin surface suggest sharks possess physiological processes that are selective on microbial associates. Sharks produce a thin integument mucus layer that likely acts to regulate microbial activity, similar to that of teleost fishes. Our findings build on the understanding of shark interactions with their surrounding environment.

0056 AES Morphology & Physiology, Carson 2, Sunday 19 July 2015
Jonathan Davis
Texas Parks and Wildlife Dept, Pleasure Island, TX, USA

Plasma Solute Properties, Movements, and Structure of Bull Shark, Carcharhinus leucas, Populations in Sabine Lake and Lake Pontchartrain: A Comparative Study

The euryhaline bull shark, Carcharhinus leucas, is found in many coastal habitats throughout the Gulf of Mexico. The C. leucas populations were sampled in two estuarine systems to assess structure, movements, and osmoregulatory parameters: Lake Pontchartrain, Louisiana and Sabine Lake, Texas. The population structures were similar in both locations with mean size and sex not being significantly different through analysis of University of New Orlean’s Nekton Research Laboratory data from 2000- 2013 and Texas Parks and Wildlife Coastal Fisheries data from 1986-2015. The C. leucas movements were seasonally influenced based on temperature in both areas according to an acoustic receiver monitoring array and seasonal collections. The plasma solute concentrations were determined from blood taken during the last year in each location. The Na+, K+, Cl-, Mg2+, Ca2+, urea and TMAO concentrations were significantly different between locations. Lake Pontchartrain is more stable in regards to salinity than Sabine Lake and as a result Sabine Lake bull sharks exhibited more fluctuation in these solute concentrations throughout the seasons. In summary, comparisons of two C. leucas populations from two distinct coastal habitats resulted in similar movements and structure while revealing a fluctuation in plasma solute concentrations due to variable salinity levels.

0357 AES Morphology & Physiology, Carson 2, Sunday 19 July 2015
Hannah Hart 1, Andrew Evans 2, Jim Gelsleichter 1, Greg Ahearn 1

1 University of North Florida, Jacksonville, FL, USA, 2 University of Southern Mississippi Gulf Coast Research Lab, Ocean Springs, MS, USA

Molecular Identification and Functional Characteristics of Peptide Transporter 1 (PEPT1) in the Bonnethead Shark (Sphyrna tiburo)

Elasmobranchs are considered top predators with worldwide distribution, and in general these fish play an important role in the transfer of energy from the lower to the upper trophic levels within marine ecosystem. Despite this, little research regarding the rates of prey ingestion, digestion, and processes of energy and nutrient absorption have been explored. Specifically understudied is enzymatic digestion within the intestinal brush border that functions to break down macromolecules into smaller subunits for luminal absorption across the gastrointestinal epithelium. Given their carnivorous diet, the present study sought to expand knowledge on nutrient intake in elasmobranchs by focusing on the uptake of products of protein metabolism. To accomplish this, Peptide Transporter 1 (PEPT1), a protein found within the brush border membrane (BBM) of higher vertebrates that is responsible for the translocation and absorption of small peptides released during digestion by luminal and membrane- bound proteases, was molecularly identified in the bonnethead shark (Sphyrna tiburo) using degenerate primers based on conserved portions of known PEPT1 sequence in Atlantic stingray. The transporter was also localized by immunocytochemistry with rabbit polyclonal anti- rat PEPT1 and the Vector ImmPRESS anti-rabbit kit in all the same organs. Vesicle studies were used to identify the affinity of the transporter, and to quantify the rate of uptake using 3H-glycylsarcosine. Such results provide insight into the rate and properties of food passage within S. tiburo, and can lead to topics such as physiological regulation of protein metabolism, and how it may vary in elasmobranchs that exhibit different feeding strategies.

0023 AES Morphology & Physiology, Carson 2, Sunday 19 July 2015
John Whalen 1, Jim Gelsleichter 1, Dean Grubbs 2

1 University of North Florida, Jacksonville, FL, USA, 2 Florida State University Coastal and Marine Laboratory, St. Teresa, FL, USA

Using DNA Adducts to Examine Polycyclic Aromatic Hydrocarbon Exposure in Shark Populations Affected by the Deepwater Horizon Oil Spill

The Deepwater Horizon oil spill (DWH) released 5 million barrels of crude oil into the Gulf of Mexico (GOM) between April and July of 2010, posing significant health risks to deepwater shark species because of the high concentration of oil and its most toxic components, polycyclic aromatic hydrocarbons (PAHs). Exposure to PAHs results in increased expression of metabolic enzymes necessary for the biotransformation and excretion of these compounds. Occasionally, metabolites resulting from this process can bind to DNA, forming adducts and creating the potential for mutagenic effects. The objective of this study was to determine if increased PAH-DNA adduct formation occurred in two abundant and ecologically important Gulf of Mexico shark species: Squalus cf. mitsukurii and Centrophorus granulosus. Animals were collected using demersal long lines from the Northeast GOM at varying distances from the origin of the DWH in 2011 and 2014. The presence of DNA adducts was determined in peripheral blood cells using immunofluorescence. Adduct formation was examined in relation to relative levels of oil exposure. A total of 52.5% of individuals examined possessed DNA adducts, ranging from 0 to 19 per 500 cells. The proportion of C. granulosus with adducted cells increased from 0.273 to 0.875 while the proportion of S. mitsukurii remained constant at 0.571, suggesting possible oil-related effects in the former. This is the first study to examine and detect the presence of PAH-DNA adducts in sharks, suggesting that they may provide a useful tool for assessing PAH effects in these fishes.

0220 AES Morphology & Physiology, Carson 2, Sunday 19 July 2015
Johanna Imhoff 1, R. Dean Grubbs 2

1 Florida State University, Tallahassee, FL, USA, 2 FSU Coastal and Marine Laboratory, St. Teresa, FL, USA

Methylmercury Contamination in Six Species of Deepwater Sharks in the Northeastern Gulf of Mexico

As mid to upper trophic level predators, elasmobranchs are at risk of carrying high loads of bioaccumulating toxicants. Methylmercury (MeHg) is of particular concern in fishes because high levels of contamination can put humans at risk for reproductive and neurological problems via fish consumption. Research on MeHg contamination in deepwater sharks has shown that MeHg concentration increases with the size of the shark, often exceeds recommended values for safe human consumption, and generally increases with increasing trophic level and dependence on benthic versus pelagic food webs. MeHg is one of several pollutants that are of particular concern after an oil spill. It has been hypothesized that oil spills create ideal conditions for blooms in the bacteria that methylate mercury. As mid to upper trophic level predators, deepwater sharks have the potential to bioaccumulate high concentrations of MeHg and their high longevity may facilitate the persistence of high levels of MeHg in the system for long periods of time. Therefore mercury analysis of coexisting deepwater sharks in a habitat near a source of anthropogenic pollution (i.e. the Deepwater Horizon oil spill) could provide useful information on the roles of taxonomy and depth habitat in toxicological response of mesopredators after an oil spill. Methylmercury speciation and levels will be analyzed in six shark species that range from the continental shelf edge to the mid-slope and include both Carcharhiniformes (Mustelus canis, M. sinusmexicanus) and Squaliformes (Squalus cubensis, S. cf. mitsukurii, Centrophorus uyato, C. granulosus).
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AES Ecology & Behavior, Carson 2, Sunday 19 July 2015 Morning

0072 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Rachel Scharer, Philip Stevens, Gregg Poulakis

Florida Fish and Wildlife Conservation Commission, Port Charlotte, FL, USA

A Comparison of Abiotic Affinities and Spatiotemporal Distribution Patterns in Two Smalltooth Sawfish, Pristis pectinata, Nursery Areas

Research on the endangered Smalltooth Sawfish (Pristis pectinata) in the Charlotte Harbor estuarine system in southwest Florida has been ongoing for about a decade and we have begun to understand the life history, ecology, and habitat use patterns of this species. Sawfish are known to use multiple southwest Florida estuaries during the first 2-3 years of life and preliminary genetics analyses have indicated that adult females are returning to the same regions (e.g., major rivers) for parturition. Thus, understanding region-specific habitat use patterns has become important for effective management. Our initial research (2005-2009) was focused in the Caloosahatchee River; a highly human-altered river system within the federally designated Critical Habitat for juveniles. Most recently (2010-2013), we continued research in the Caloosahatchee and expanded sampling into a more natural area, the Peace River. A total of 135 juveniles ranging from 708 to 2,640 mm stretch total length were captured, tagged, and released between February and September. Annual recruitment peaked during April and May in both river systems. Logistic regression models identified combinations of water depth, water temperature, dissolved oxygen, and salinity as influencing the probability of catching a sawfish. Electivity analyses showed that sawfish in both rivers had affinities for water <1 m deep, water >24°C, moderate to high dissolved oxygen levels (>4 mg l-1), and salinities between 12 and 27. Possible reasons for differences in dissolved oxygen and salinity affinities between the rivers relate to differences in their geomorphology and freshwater inflow regimes.

0073 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Gregg Poulakis, Philip Stevens, Rachel Scharer

Florida Fish and Wildlife Conservation Commission, Port Charlotte, FL, USA

A Comparison of Movement Patterns in Two Smalltooth Sawfish, Pristis pectinata, Nursery Areas

Movements of endangered juvenile (<3 yr old) Smalltooth Sawfish (Pristis pectinata) were monitored in the highly human-altered, freshwater inflow-managed Caloosahatchee River (2005-2013) and in the more natural Peace River, Florida (2010- 2013) using 63 acoustic listening stations. A total of 133 sawfish (76 in the Caloosahatchee River; 57 in the Peace River) were monitored in main-stem river habitats and non-main-stem habitats (i.e., natural mangrove-lined creeks, semi-natural creeks, seawall-lined canals) of both river systems. Sawfish used all of the habitats available to them in both rivers, but tended to reside in specific regions of the nurseries. In the Caloosahatchee River, sawfish were usually associated with five hotspots that contained natural shoreline habitats along a 25 river kilometer (rkm) stretch of the nursery. They moved upriver during dry, low freshwater inflow conditions and downriver during wet, high inflow conditions. In contrast, in the Peace River, sawfish tended to remain in only a 6 rkm portion of the nursery during all freshwater inflow conditions. This portion of the nursery includes the only hotspot that has been identified in the Peace River. Possible reasons for these observations relate to differences in geomorphology and freshwater inflow regimes between the rivers.

0444 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Diana A. Churchill 1, Michael R. Heithaus 1, R. Dean Grubbs 2

1 Florida International University, Miami, FL, USA, 2 Florida State University, Tallahassee, FL, USA

Estimating the Trophic Position of Deep-water Sharks and Associated Species Using Compound-specific Nitrogen Isotope Analysis of Amino Acids

The ability to estimate trophic position is an important step in understanding the ecological roles of deep-sea animals. Determining absolute trophic levels using whole tissue stable isotope analysis is often problematic because of the inter- and intra-specific variation associated with trophic discrimination factors. Some of this variability may be eliminated by using compound-specific nitrogen analysis of proteinaceous amino acids. Using this technique, we were able to estimate the trophic position of numerically abundant deep-sea organisms. Tissue samples were collected from demersal fish (sharks, hake, tilefish, and cutthroat eels) and benthic scavengers (giant isopods, hagfish, crabs and shrimp) captured at depths of 200-1500 m along the northern slope (NGS) and the west Florida slope (WFS) of the Gulf of Mexico during 2011 and 2012. Whole muscle tissue δ15N analyses reveal that these consumers span approximately 2 trophic levels, with the armed nylon shrimp (Heterocarpus ensifer) at the lowest relative trophic position and the little gulper shark (Centrophorus cf. uyato) at the highest. Compound-specific analyses will determine absolute trophic positions for the sampled deep-sea animals using source and trophic amino acid δ15N values as well as examine possible isotopic baseline differences between the NGS and WFS.

0219 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Cheston Peterson 1, R. Dean Grubbs 1, 2
1 Florida State University, Tallahassee, FL, USA, 2 FSU Coastal and Marine Laboratory, St. Teresa, FL, USA

Investigating Trophic Relationships Between Sharksuckers (Echeneis naucrates) and Their Elasmobranch Hosts Using Stable Isotope Analysis

Despite the ubiquity of the symbiotic relationships of diskfishes (Echeneidae) and their hosts in marine ecology, the nature of the symbioses between individual species and their hosts is poorly understood - especially among the facultative symbionts (Echeneis sp.). We used carbon and nitrogen stable isotope analysis of white muscle biopsies from both free-living and commensal sharksuckers (Echeneis naucrates), as well as their hosts, to evaluate the suggestion that commensal sharksuckers feed heavily on scraps of their hosts' prey. We also used these data to evaluate among-host differences in pairwise similarity of individual sharksucker and host isotopic signatures, which we hypothesize could be indicative of long-term commensalism or high quality hosts. Mean pairwise differences of both δ13C and δ15N were lowest in bull (Carcharhinus leucas) and lemon (Negaprion brevirostris) sharks, and highest in nurse (Ginglymostoma cirratum) and tiger sharks (Galeocerdo cuvier). There was no effect of host taxon on pairwise δ13C differences, but there was a significant effect of host taxon on pairwise δ15N differences. Similarly, there was not an effect of commensalism on δ13C, accounting for variation in sharksucker size and collection location; however, there was an effect of commensalism on δ15N, accounting for variation in sharksucker size and collection location. Despite being larger in size, free-living sharksuckers had lower δ15N values, and therefore relative trophic position, than commensal sharksuckers. Our results suggest relative trophic levels of sharksuckers drop when they are free-living and that there may be an ontogenetic shift in both dependency on commensalism and trophic level.

0248 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Robert J. Nowicki, Jordan A. Thomson, James W. Fourqurean, Michael R. Heithaus

Florida International University, Miami, FL, USA

Effects of Predation Risk from Tiger Sharks (Galeocerdo cuvier) on Resilience of an Iconic Seagrass Ecosystem Following a Widespread Climate Driven Disturbance

Ecological resilience will play an important role as anthropogenic ecosystem disturbance continues. Understanding how marine apex marine predators contribute to resilience is important in the context of global overfishing and increased disturbance potential from climate change. Here I present a 16 month field experiment to determine whether a dominant apex predator, the tiger shark (Galeocerdo cuvier), contributes to the stability of the recently disturbed seagrass community of Shark Bay, Australia. Shark loss was mimicked by simulating shifts in risk-sensitive habitat use and foraging patterns of dugong mega-grazers. Different levels of dugong excavation grazing, imitated by divers, were applied to plots to characterize these shifts. Excavation is energetically profitable to dugongs but destructive to seagrass beds, removing both target and non- target seagrass; it also increases risk of predation and is rarely used when predators are abundant. Mixed effects modeling was used to determine the importance of grazing treatments to the change in percent cover of the dominant climax seagrass (Amphibolis antarctica) and an herbivore-preferred pioneer seagrass (Halodule uninervis). A. antarctica cover declined with shark loss and subsequent increased grazing, though the effects were site-dependent. H. uninervis also declined but was more variable. Results indicate the current, fragile state of Shark Bay and the likelihood for a phase shift to an A. antarctica depauperate ecosystem if tiger sharks were removed from the ecosystem. This work highlights the contribution apex predators can make to the resilience of marine ecosystems, as they become exposed to more frequent and intense disturbances through climate change.

0158 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Rui Matsumoto 1, Miwa Suzuki 2, Kiyoshi Asahina 2, Kiyomi Murakumo 1, Yosuke Matsumoto 1, Keiichi Ueda 1, Keiichi Sato  3

1 Okinawa Churaumi Aquarium, Okinawa, Japan, 2 Nihon University, Kanagawa, Japan, 3 Okinawa Churashima Research Center, Okinawa, Japan

Long-term Observation of the Behavioral and Hormonal Trends in Male Whale Shark in the Okinawa Churaumi Aquarium

The maturation cycle of a male whale shark kept in the Okinawa Churaumi Aquarium for 20 years was recorded. This shark (total length [TL], 4.6 m) was accidentally caught by local fishermen in March 1995. In order to determine the exact size of this shark at maturation, we have monitored the clasper elongation; the elongation was defined as the ratio of the outer length (COL) of the clasper to the length of the inner pelvic margin (P2I). Analysis revealed that this ratio increased rapidly from 1.09 (August 2011) to 1.60 (July 2012), and the shark attained a length of 8.5 m TL. A high plasma testosterone level was maintained at 21.49 ng/mL (June 2011-June 2012) during rapid clasper elongation. Additionally, we observed a behavioral change where the whale shark began to rotate its entire body laterally, while crossing both claspers (April 2012) and simultaneously discharged white turbid fluid from its clasper tips (August 2012). We continued to monitor the behavioral and hormonal changes in the shark. In May 2014, the male began demonstrating sexual behavior by pursuing two immature female sharks (7.5 m and 7.4 m TL). In June 2014, we continued to monitor this pursuing behavior and began counting the number of clasper rotating actions as well as measured the hormone levels and water temperature. Current observations indicate that the clasper rotation and pursuing action increased in frequency at higher water temperatures (25-28°C) from June to early August and did not occur in lower temperature waters.

556 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Csilla Ari 1, 2, 3, Dominic D`Agostino 1

1 University of South Florida, FL, USA, 2 Foundation for Oceans of the Future, Budapest, Hungary, 3 Manta Pacific Research Foundation, HI, USA

Sensory and Cognitive Experiments on Giant Manta Rays

Large, complex and highly foliated brain of Mobulid species suggest good sensory abilities and complex social behavior. The largest brain of all fish species is possessed by manta rays with exceptionally large optic tectum and telencephalon among elasmobranchs. Visual accuracy and wavelength sensitivity were tested on two captive giant manta rays and evidence for visual threshold and wavelength discrimination abilities were found. Self-recognition is one of the more advanced cognitive skills, which has never been proven in any fish species so far. Manta rays have high encephalization quotient similarly to those species that passed the mirror self recognition test, therefore mirror exposure experiments were conducted on two captive giant manta rays to document their response to their mirror image. The present studies show contingency checking and self-directed behavior of manta rays when exposed to a mirror, implying higher order brain function, sophisticated cognitive and social skills.

00020 AES Ecology & Behavior, Carson 2, Sunday 19 July 2015
Peter Klimley 1, David Acuna 2, Randall Arauz 3, Sandra Bessudo 4, Eduardo Espinosa 5, Hector Guzman 6, Alex Hearn 7, Mauricio Hoyos 8, James Ketchum 8, Cesar Penaherrera 9, George Shillinger 10, German Soler 4
1 University of California, Davis, CA, USA, 2 Charles Darwin Foundation, Puerto Ayora, Santa Cruz Island Galapagos, Ecuador, 3 Programa Restauracion Tortugas Marinas, San Jose, Costa Rica, 4 Fundacion Malpelo, Bogota, Colombia, 5 Parque Nacional Galapagos, Puerto Ayora, Santa Cruz Island, Ecuador, 6 Smithsonian Tropical Research Institute, Panama City, Panama, 7 Turtle Island Restoration Network, Forest Knolls, CA, USA, 8 Pelagios Kakunja, La Paz, Baja California Sur, Mexico, 9 University of Tasmania, Hobart, Tasmania, Australia, 10 Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA

The Role of Geology and the Design of Marine Reserves for Sharks in the Eastern Pacific

Nine species of sharks are commonly are present at "hot spots", at seamounts and islands in the Eastern Pacific. The movements of these species have been described at the Espiritu Santo Seamount and Revillagigedos, Cocos, Coiba, Malpelo, and Galapagos Islands by (1) shipboard tracking, (2) satellite tracking, and (3) coded beacon detection by autonomous receivers. The whitetip reef, silvertip, blacktip, and tiger sharks are seasonally insular, staying most of the time close to shore. The Galapagos, scalloped hammerhead, silky, and small-tooth sandtiger sharks are seasonally insular-pelagic, making daytime or nighttime foraging migrations into the pelagic environment. The whale shark is truly pelagic, moving widely throughout the ocean while only briefly visiting these hot spots. These sites are of volcanic origin, being formed by the extrusion of basalt containing single-domain particles of magnetite from the earth's lithosphere that align to the polarity of the earth's field as the basalt cools after eruptions. The polarity of the earth's main field rotates periodically over geological time so the lava flows contain magnetite aligned parallel and anti-parallel to the current earth's field forming maxima ("ridges") and minima ("valleys") in the earth's field to which sharks may orient using magnetic "topotaxis". It is suggested that these magnetic features limit extent of the feeding excursions of these species, and knowledge of their extent can be used to specify zones of enforcement of fishing prohibitions at these sites so that they can continue to generate revenue as "shark parks".
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AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015 Afternoon

0205 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Steven Kessel 1, Alexander Hansell 4, Samuel Gruber 1, Tristan Guttridge 1, Nigel Hussey 2, Rupert Perkins 3

1 Bimini Biological Field Station Foundation, Bimini, Bahamas, 2 University of Windsor, Windsor, Canada, 3 Cardiff University, Cardiff, UK, 4 University of Massachusetts, Fairhaven, MA, USA

Lemon Shark (Negaprion brevirostris) Catch Per Unit Effort (CPUE) Trends, Bimini, Bahamas, Derived from a Fishery Independent, 32-year Shallow Water Longline Survey

Long-term population assessments are necessary to determine species specific trends and inform management decisions. The waters surrounding the Bimini Islands, Bahamas, are rich in elasmobranch fauna. This study assessed three shallow water longline research campaigns at this location, 1982 - 1992, 1993 - 2003 and 2004 - 2014, with the aim to determine annual catch per unit effort (CPUE) trends for an IUCN listed near threatened species, the lemon shark (Negaprion brevirostris). A general additive model (GAM) was used to analyse the non-linear annual CPUE values over the entire 32 year research period. The GAM displayed high variability of annual CPUE, with a peak value of 0.026 in 2000. The 1982-1992 campaign saw highest portion of mature individuals (19.8%) and the smallest average pre-caudal length [PCL] (198 cm). The 1993 - 2003 campaign had the highest average annual CPUE (0.018) and percentage of total capture (32.3%). The 2004 - 2014 research period saw largest average PCL size (134.8 cm) and the lowest average CPUE values (0.009) of the entire research period. Long-term trends of this study highlight annual variability, and provide a baseline for future assessment of the Bahamas shark sanctuary relative to lemon shark abundance.

0217 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Taketeru Tomita 1, Masaru Nakamura 2, Keiichi Sato 2, Hiroko Takaoka 3, Minoru Toda 2, Junro Kawauchi 4, Kazuhiro Nakaya 4

1 Florida State University Coastal and Marine Laboratory, St Teresa, FL, USA, 2 Okinawa Churashima Research Center, Motobu, Okinawa, Japan, 3 Okinawa Churaumi Aquarium, Motobu, Okinawa, Japan, 4 Hokkaido University, Hakodate, Hokkaido, Japan

Changes in Catshark Embryo Respiratory Mode During Mid-embryonic Period

Elasmobranchs are unique among fishes in producing extremely large embryos. Such a large embryo, with low body surface-volume ratio, may present respiratory challenges in utero. This is because gas diffusion solely through the body surface does not meet the oxygen demand for large embryos. Thus, some specific respiratory mechanisms are expected. Morphological and kinematical observations on captive catshark embryos have suggested that the embryo switches its respiratory mode just before the respiratory slits open on the egg capsule. During the pre-opening period, the embryo acquires oxygen mainly via diffusion in the external gill filaments. After slit opening, embryo starts buccal pumping to pass water over the internal gills. Some structural modifications (e.g., development of blood vessels in internal gills, development of oral valve, and establishment of pharyngeal skeletons and associated muscles) occur at the same time. It is known that the oxygen tension in the egg capsule is quite unstable after slit opening. The ability of buccal pumping is possibly advantageous for embryos to regulate oxygen intake by changing pumping frequency in an unstable oxygen environment.

0063 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Aaron Carlisle 1, Mark Denny 2, Nishad Jayasundara 3, Adrian Gleiss 4, Elliot Hazen 1, Heidi Dewar 1, Salvador Jorgensen 5, Barbara Block 2, Steven Bograd 1
1 NOAA Southwest Fisheries Science Center, Monterey, CA, USA, 2 Stanford University, Pacific Grove, CA, USA, 3  Duke University, Durham, NC, USA, 4 University of Western Australia, Perth, WA, Australia, 5 Monterey Bay Aquarium, Monterey, CA, USA

Linking Thermal Physiology with Habitat Availability in Juvenile Lamnid Sharks

Sharks in the family Lamnidae are unique in that they are endothermic, and maintain an elevated body temperature relative to ambient water temperature. An inability to maintain an elevated body temperature in response to thermal challenges can have serious consequences on the survival and fitness of these sharks. This is particularly relevant for neonates and small juveniles which may be thermally limited due to their low thermal inertia, potentially restricting them to moderate or warm water temperatures in which they are able to maintain elevated core temperatures. These potential thermal requirements provide us with a unique opportunity to explore the thermal niche of young juvenile lamnid sharks and model potential nursery habitats based on temperature. We created a biophysical heat-balance model for three species of lamnid shark (white, mako, and salmon sharks) to investigate the theoretical lower thermal limits of juvenile lamnid sharks and explore how this limit changes with size. Model results were compared to the observed thermal niche of juvenile lamnid sharks based on survey, bycatch and electronic tag data from their shared nursery area of the California Current. Understanding the mechanisms which may define thermal limits for these sharks allows us to investigate how physiology interacts with environmental conditions to influence habitat availability across spatial and temporal scales and through ontogeny.

0144 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Christopher Lowe 1, Connor White 1, Diego Bernal 2

1 California State Univ. Long Beach, Long Beach, CA, USA, 2 Univ. Mass. Dartmouth, Dartmouth, MA, USA

Behavioral Thermoregulation in Elasmobranch Fishes: What Do We Know and Where Do We Go from Here?

There is a growing number of telemetry-based movement studies across a range of ectothermic elasmobranch species suggesting that individuals exhibit some form of behavioral thermoregulation. In addition, there is considerable speculation as to the benefits of this behavior and what potentially drives movements relative to changing water temperatures. Fewer studies have focused on quantifying the actual physiological cost/benefits of changing body temperatures and how these changes may influence behavior. Unfortunately, in a vast majority of cases there is little physiological and behavioral data for the same species to allow for realistic assessment of potential behavioral thermoregulation. Cases where there are comparable physiological and behavioral data have focused primarily on smaller species that are easier to keep in captive settings. As a result, our understanding of how behavioral thermoregulation scales with body size is sorely lacking. New technology, experimental designs, and modeling tools may allow for a better assessment of behavioral thermoregulation. New movement (accelerometer, temp and depth dataloggers) and tracking tools (VRAP, MAP600, AUVs) can allow for simultaneous, fine-scale assessment of movements relative to environmental conditions, especially if accompanied with internal body temperature sensors (e.g., gastric or IP temperature sensors). Use of field-based translocation experiments across thermal gradients may allow for experimental assessment of body temperature and movement predictions. Lastly, better physiological, behavioral and related environmental data will allow for more sophisticated modelling to predict movement patterns as ocean temperatures continue to warm.

0530 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Christopher Clark 1, Yukun Lin 1, Jerry Hsiung 1, Connor White 2, Christopher Lowe 2

1 Harvey Mudd College, Claremont, CA, USA, 2 California State University Long Beach, Long Beach, CA, USA

Planning, Control, and State Estimation for Animal Tracking with Autonomous Robots

The field of robotics has generated viable solutions to the planning, control and state estimation problems encountered when enabling mobile robots with autonomous capabilities. In this talk, such solutions are presented in the context of a particular application: the use of underwater robot systems for autonomous tracking of individual fish tagged with acoustic transmitters. Over the past 4 years, a multi-AUV (Autonomous Underwater Vehicle) system has been developed that is equipped with hydrophones and receivers to detect, localize, and autonomously follow tagged individuals. Experiments conducted in Big Fisherman's Cove, CA demonstrate localization errors on the order of 6 meters when tracking tagged boats. When deployed to track tagged leopard sharks, the AUVs are able to track and follow the individuals for hours at a time, while simultaneously obtaining environment data, (e.g. bathymetry). AUV Path Planning is accomplished via graph search algorithms that ensure AUV paths do not intersect with obstacles or kelp beds. Decentralized AUV control laws enable the AUVs to circle a moving individual without affecting the animal's behavior. Particle Filter state estimation algorithms are leveraged to successfully track the individual in real-time. Most recently, individuals have been tagged with a "smartTag" that houses an acoustic transmitter, video camera, automatic release system, and Inertial Measurement Unit. The use of this smartTag has decreased fish position estimation error by a factor of 2, and orientation estimation error by a factor of 4. Notably, the hardware and software techniques utilized are generalizable to a large class of tracking applications.

0101 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Daniel Coffey, Kim Holland

Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, HI, USA

In Situ Measurements of Dissolved Oxygen from a Vertically Migrating Deepwater Shark, the Bluntnose Sixgill (Hexanchus griseus)

Advances in biologging technology have enhanced our understanding of the ecology of marine animals and have been central to identifying how contemporary oceanographic conditions establish patterns in their distribution and behavior. In particular, the impact of dissolved oxygen on the vertical distribution of marine animals is becoming increasingly recognized. Insights into the impact of oxygen on vertical movements would be advanced by in situ measurements of dissolved oxygen from animal-borne sensors instead of relying on model-derived, climatological data. Here we demonstrate the capabilities of a novel dissolved oxygen pop-up satellite archival tag (DO-PAT) by presenting the results from calibration experiments and trial deployments on bluntnose sixgill sharks (Hexanchus griseus). The DO-PATs provided fast, accurate, and stable measurements in calibration trials and conductivity-temperature-depth (CTD) vertical profiles. In addition, initial deployments on H. griseus effectively captured the oceanography of the region when compared with World Ocean Atlas 2013 values. This is the first study to demonstrate the use of an animal-borne device for measuring in situ dissolved oxygen saturation. The information returned from DO-PATs is relevant not only to the study of the ecology of marine animals but will also become a useful new tool for investigating the physical structure of the oceans.

0083 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Joshua K. Moyer, William E. Bemis
Cornell University, Ithaca, NY, USA

Comparisons of Tooth Structure and Replacement in the Blue Shark (Prionace glauca) and the Great White Shark (Carcharodon carcharias)

Elasmobranchs exhibit two distinct arrangements of mineralized tissues in the teeth that are known as orthodont and osteodont histotypes. Traditionally, it has been said that orthodont teeth maintain a pulp cavity throughout tooth development whereas osteodont teeth are filled with osteodentine and lack a pulp cavity when fully developed. We used light microscopy, scanning electron microscopy, and high- resolution micro-computed tomography to compare the structure and development of elasmobranch teeth representing the two histotypes. As an example of the orthodont histotype, we studied teeth of the Blue Shark, Prionace glauca (Carcharhiniformes: Carcharhinidae). For the osteodont histotype, we studied teeth of the Great White Shark, Carcharodon carcharias (Lamniformes: Lamnidae). We document similarities and differences in tooth development and the microstructure of tissues in these two species and review the history of definitions and interpretations of elasmobranch tooth histotypes. We discuss a possible correlation between tooth histotype and tooth replacement and review the history of histotype differentiation in sharks. We find that contrary to a long held misconception, there is no orthodentine in the osteodont teeth of C. carcharias.

0463 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Matthew Kolmann, Nathan Lovejoy
University of Toronto Scarborough, Toronto, Ontario, Canada

Feeding Kinematics of the Ocellate River Ray, Potamotrygon motoro

Marine to freshwater incursions are comparably rare events, although several fish lineages have bridged the ecological and physiological boundaries inherent to these transitions. The South American river rays, Potamotrygonidae, invaded freshwater at least 14 mya and have subsequently diversified into nearly 30+ species. From a generalist invertivore ancestor, several instances of piscivory, mulloscivory, and insectivory have arisen independently in this clade of stingrays. For dietary generalists like Potamotrygon motoro, considerable behavioral modulation is assumed to be necessary to consume such a wide swath of prey taxa and prey materials. Here we present data on prey-handling in P. motoro filmed on bare-bottom enclosures using high- speed videography. We report the degree of asymmetrical jaw protrusion, relevant for processing large or tough prey as well as the general behavioral routines involving prey capture, prey processing, and overall handling time. We find that these rays utilize an initial "pounce" to apprehend prey, followed by repeated jaw protrusion and retraction, during which indigestible prey material is ejected from the spiracles. Prey-handling times increase for larger prey items as well as the degree to which jaw asymmetrical protrusion is observed. Based on prior myological studies, we hypothesize then that the coracohyomandibularis and levator hyomandibularis aid in hyoid depression and retraction (respectively), and when coupled with the coracomandibularis, protrude the jaws. These muscles in particular may be relevant to further study of functional feeding trait evolution in the Potamotrygonidae.

0520 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Sebastian Pardo 1, Marc Dando 2, Nick Dulvy 1
1 Simon Fraser University, Vancouver, BC, Canada, 2 FlukeArt, Plymouth, UK

Can Fin Shape Explain Variation in Somatic Growth Among Shark Species?

Across vertebrate taxa, morphology is related to function. An example from fishes is that caudal fin shape relates with swimming speed and activity level, with more elongated fins indicative of fast, active species and rounded fins slower, inactive ones. There is evidence that activity levels correlate with food consumption (more active fish eat more prey), and given that food consumption is relative to somatic growth rate (the more you eat the faster you grow), it might be possible to explain observed variation in growth among species based on a simple measure of fin morphology: caudal fin aspect ratio. Here we present a framework for exploring the relationship between somatic growth rate, maximum size, ocean temperature, and aspect ratio among a range of shark species, and discuss preliminary findings.

0033 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Emily Nelson 1, Neil Hammerschlag 1, 2, Duncan Irschick 3

1 Rosenstiel School of Marine and Atmospheric Science, Miami, FL, USA, 2 Leonard and Jayne Abess Center for Ecosystem, Science and Policy, Coral Gables, FL, USA, 3 Department of Biology, University of Massachusetts at Amherst, Amherst, MA, USA

Variation in Body Form Influences Broad Scale Movement Patterns and Ecological Locomotor Performance by an Apex Predator

Throughout the long evolutionary history of sharks, physical, hydro-dynamical, and ecological demands have created considerable selection pressure to create the most efficient design for locomotion. Variation in body shape can impact an individual’s ability to move effectively through the water and variation in body condition can influence the timing, length, and nature of migrations. Here we present a functional approach toward movement. We integrate functional morphology, physiology, and ecology to determine how variation in body form influences broad scale movement patterns and ecological locomotor performance of a marine apex predator (the tiger shark, Galeocerdo cuvier). Fourteen tiger sharks, ranging in size from 180 cm to 357 cm (total length) were captured. For each individual, 13 morphological measurements were taken and sharks were tagged with satellite transmitters to track their movement patterns. Using these data we evaluated how variation among individuals in movement (maximum distance moved, dispersion rate, rate of movement, kernels density, activity space, and area used per day) is influenced by morphology (caudal fin area, caudal fin aspect ratio, total length, and body condition). Our results help to understand the mechanisms underlying of the ecological and evolutionary implications of variation in morphological adaptations on marine apex predator movement and behavior.

0526 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Bryan Frazier 1, Dana Bethea 2, William Driggers 3, Robert Hueter 4, John Tyminski 4

1 South Carolina Department of Natural Resources, Charleston, SC, USA, 2 NOAA Southeast Fisheries Science Center, Panama City, FL, USA, 3 NOAA Southeast Fisheries Science Center, Pascagoula, MS, USA, 4 Mote Marine Laboratory, Pensacola, FL, USA

Growth Rates of Bonnetheads (Sphyrna tiburo) from the Western North Atlantic Ocean Estimated from Tag-Recapture Data

Regional variation in growth has been observed for multiple species of elasmobranches. Recently, published age and growth models for bonnetheads (Sphyrna tiburo) reported larger than expected life history differences between sharks from the eastern Gulf of Mexico and off the coast of South Carolina. Growth can be estimated independent of age by using length based growth models. A maximum likelihood approach (GROTAG) was used to analyze direct growth estimates from tag-recapture derived data. Region and sex-specific models were generated allowing investigation of regional growth, and likelihood ratio tests were used to determine optimal parameterization of the models. Parameters explored included individual growth variability, seasonal growth, measurement error and outliers for each data set. A comparison of region-specific length based models to published age-based models for bonnetheads will be discussed.

0528 AES Morphology, Ecology, & Physiology, Carson 2, Sunday 19 July 2015
Eric Hoffmayer 1, Jennifer McKinney 2, Jill Hendon 3, James Franks 3, Brett Falterman 2, William Driggers 1

1 National Marine Fisheries Service, Pascagoula, MS, USA, 2 Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA, USA, 3 Gulf Coast Research Laboratory, Ocean Springs, MS, USA

Northern Gulf of Mexico Whale Shark Research Program: What We Have Learned about Whale Shark Aggregations in the Northern Gulf of Mexico

The Northern Gulf of Mexico Whale Shark Research Program was initiated in 2003 to increase our knowledge of whale shark occurrence and distribution within the region. A primary component of this program is a whale shark sighting website, which accommodates reports of regional sightings by “citizen scientists.” Whale sharks aggregate in areas of high prey abundance and our hope was to examine factors driving this behavior in the northern Gulf of Mexico. To date, over 600 whale shark sighting reports have been received. Reports were provided by a number of groups, including recreational anglers, divers, helicopter pilots and petroleum industry personnel and were categorized as sightings of solitary individuals, small aggregations (2-9 individuals) or large aggregations (10 or more individuals). Whale shark aggregations represented 190 (31%) of reported sightings, 47 (25%) of which were large aggregations between 10-150 individuals. All of the reported large aggregations occurred during summer, almost exclusively along the continental shelf edge, with 19 (41%) occurring at Ewing Bank off Louisiana. Directed research efforts were made to encounter aggregations to determine the size and sex of the sharks within the aggregation and to identify the primary prey source(s) by collecting plankton samples. Five aggregations were encountered and appeared to consist of largely juvenile males that were feeding on little tunny (Euthynnus alletteratus) eggs. The use of sightings data provided by “citizen scientists” has proven to be an inexpensive and effective technique for characterizing whale shark distribution, seasonality and aggregation locations in the northern Gulf of Mexico.
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