| Parameter | Female | Male | References |
|---|---|---|---|
| Largest specimens (Total length and mass) |
1.981 m; 1.515 mTL | Miller and Lea (1972); Ackerman 1971 | |
| Size range of specimens | 0.226-1.450 m TL (n = 162) | Kusher et al. 1992 | |
| Size at maturity | 0.95-1.1 m TL | 1.0-1.1 m TL | Kusher et al. 1992 |
| Smallest mature | 0.94 m TL (10 yr) | 1.01 m TL (10 yr); 1.15 m TL (7 yr) | Kusher et al. 1992 |
| Largest immature | 1.08 m TL (11 yr) | 1.10 m TL (11 yr) | Kusher et al. 1992 |
| Sizes at which 10, 50, and 90% are mature |
|
Fig. 12 data in Koster et al. 1992 could be used to determine this. | |
| Estimated age at maturity | 10-13 yr | 7-10 yr | Kusher et al. 1992 |
| Gestation time | 12 months | Kusher et al. 1992 | |
| Reproductive cycle | 1 year | Kusher et al. 1992 | |
| Litter size (# of pups in litter) | 7-36 | Cortés (2002) | |
| Birth size estimate | 25 cm TL | Kusher et al. 1992 | |
| Smallest free-swimming | 25 cm TL | Kusher et al. 1992 | |
| First year growth | 9.2 cm TL based on VBGF | 10.7 cm TL based on VBGF | Kusher et al. 1992 |
 Von Bertalanffy Growth Function (VBGF) |
TLoo = 1.602 m, TLo = 0.290 m (to = - 2.74 yr), k = 0.073 yr-1 (5ln(2)/k = 47.5yr); |
TLoo = 1,499m, TLo = 0.248m (to = - 2.03 yr), k = 0.089 yr-1 (5ln(2)/k = 38.9yr); |
|
| Elasticity estimates based on alpha = 12 yr, Abar = 16.41 yr, Abar/alpha = 1.37 (AES Manaus) |
E(m) = 1/Abar = 1/16.41 = 0.0609; |
Normalized elasticities: E(fertility) = E(m) = 5.7%; E(juvenile survival) = E(JS) = 68.9%; E(adult sruvival) = E(AS) = 25.3% , E(AS)/E(JS) = 0.37 |
|
| Parameter | Female | Male | References |
Created November 2002;
updated November 2002. Back to previous page