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
itÕs 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.
*******************************************************************************************
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 Òlitany of declineÓ, 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 EuropeÕs
Elasmobranchs
The International Union for
Conservation of NatureÕs (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
ÒsafeÓ 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 Òsmooth dogfishÓ (Mustelus canis),
which feeds poorly understood markets and is the nationÕs sole subject of the
worldÕs weakest ban on shark Òfinning.Ó A complex of Northwest Atlantic skates
(Family Rajidae), used for food and bait, supports
the countryÕs largest elasmobranch fishery, yet the American publicÕs 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 ÒSave the Bay, Eat a RayÓ 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 FloridaÕs 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 TexasÕ 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 Æ14C) that are
equated to a year-of-formation, and subsequently compared to an appropriate
Æ14C 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
Æ14C 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 Æ14C measurements from vertebral samples to the Æ14C
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. MaryÕs 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 ÔEtmopterus spinaxÕ 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 ÔE. spinaxÕ 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 ÔE.spinax
cladeÕ 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 Ôoutlier' 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.
*******************************************************************************************
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
43.8±0.73% 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 ± 4.8 m, Researcher: 16.6 ± 9.7 m, F = 31.1, p
= 0.005), while generating significantly more localizations (AUV: 45.2 ± 10.5
detection/min, Researcher: 12.2 ± 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 FishermanÕs 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, HawaiÕi, 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 Ôhot spotsÕ, 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 FishermanÕs 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.
*******************************************************************************************
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 PalmyraÕs
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
PalmyraÕs 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 sharksÕ 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 Òonly as a rare stray.Ó 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 ÔresidentÕ
population inhabits the freshwater St. Johns River System (SJRS); however, the
extent of this populationÕs 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 ÔresidentÕ 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 ± 0.98 ng/standardized
liver sample compared to the mainland population, 15.7 ± 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 %
(±SE) phagocytosis of 18.85 ± 4.59, compared to peripheral blood, 8.58 ± 1.53,
and epigonal tissue, 13.11 ± 4.93. Blood demonstrated
a higher measure of the phagocytesÕ activities, with a mean fluorescence
intensity (±SE) of 2244.90 ± 265.63, whereas cells isolated from spleen and epigonal were calculated as 1568.65 ± 211.87 and 796.15 ±
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 ± SD, 11.1 ± 1.0 versus 22.8 μg g-1 lw),
but had substantially higher concentrations of pesticides (4.1 ± 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 sharkÕs 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
ÔSPOT A BASKING SHARKÕ: 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 ÔSpecies of
ConcernÕ by NOAAÕs National Marine Fisheries Service and ÔEndangeredÕ by the
International Union for the Conservation of Nature (IUCN). The ÔSpot a Basking
SharkÕ 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.
**************************************************************************************
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. WeÕve 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 Òbrain
warmingÓ, 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 (ÒstressedÓ
and ÒunstressedÓ). 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.
*******************************************************************************************
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 ÒsupersuckerÓ 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 OrleanÕs 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).
*******************************************************************************************
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".
*******************************************************************************************
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
individualÕs 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 Òcitizen scientists.Ó 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 Òcitizen scientistsÓ has proven to be an
inexpensive and effective technique for characterizing whale shark
distribution, seasonality and aggregation locations in the northern Gulf of
Mexico.
**************************************************************************************************************************************************************************************