Vital Rates (Life History Parameters)
of the Gray Smoothhound, Mustelus californicus
Vital Rates (Life History Parameters)
of the Gray Smoothhound, Mustelus californicus
| Parameter | Female | Male | References |
|---|---|---|---|
| Largest specimens (Total length and mass) |
1.632; 1.26 m TL; | 1.16; 0.93 m TL | Miller and Lea 1972; Compagno 1984; Yudin and Cailliet 1990 |
| Size range of specimens | 0.235-1.259 mTL (n=31) | 0.275-0.930 m TL (n=27) | Yudin and Cailliet 1990 |
| Size at maturity | 0.70 m TL | 0.57-0.65 m TL | Yudin and Cailliet 1990 |
| Smallest mature | |||
| Largest immature | |||
| Sizes at which 10, 50, and 90% are mature |
|
||
| Estimated age at maturity | 2.1 yr (using VBGF with TL = 0.70 m) | 1.4-1.9 yr (using VBGF with TL = 0.57-0.65 m) |
Yudin and Cailliet 1990; however they reported 1-4 yr for age-at-maturity in abstract? |
| Gestation time | 6 months? | ||
| Reproductive cycle | 1 year | Cortés (2002) | |
| Litter size (# of pups in litter) | 2-5 | Yudin and Cailliet 1990;, Cortés (2002) | |
| Birth size estimate | 20-30 cm TL | Yudin and Cailliet 1990 | |
| Smallest free-swimming | 23.5 cm TL | Yudin and Cailliet 1990 | |
| First year growth | 22.3 cm TL based on VBGF | 21.2 cm TL based on VBGF | Yudin and Cailliet 1990 |
Von Bertalanffy Growth Function (VBGF) |
TLoo = 1.424 m, TLo =0. 287 mm (to = - 1.032 yr), k = 0.218 yr-1 (5ln(2)/k = 15.9 yr); |
TLoo = 1.018 m, TLo =0. 301mm (to = - 1.002 yr), k = 0.350 yr-1 (5ln(2)/k = 9.9 yr); |
|
| Elasticity estimates based on alpha = 3.0 yr, Abar = 4.80yr, and GP = 0.5 yr | E(m) = 1/Abar = 1/4.80 = 0.208; E(JS)/E(m) = alpha - GP = 2.5, E(JS) = 0.521; E(AS)/E(m) = Abar- alpha+GP = 2.2, E(AS) = 0.480; Sum Elasticity Ratios = Abar = 4.8 yr; Sum Elasticities = 1 + E(M) = 1.21 |
Mollet 2003 (AES Manaus) Normalized elasticities: E(fertility) = E(m) = 17.2 %; E(juvenile survival) = E(JS) = 43.1%; E(adult sruvival) = E(AS) = 39.7% |
|
| Parameter | Female | Male | References |
Vital rates needed for demograhic analysis are age-specific
mortality rate M (can be estimated from longevity), age-at-first reproduction
(alpha = age-at-maturity + gestation period), longevity estimate w (can
be estimated from Von Bertalanffy growth curve), and fertility m (number
of female pups born per year). The following values were used by Cortés
(2002) in a demographics analyses of 39 shark species:
M = 0.53-0.83 yr-1; Alpha =1, 2.5, 4 triangular distribution;
w = 9.0 years; m =(2-5)/2= 1.0-2.5 uniform distribution
Results: Lambda = 1.132, Abar = 4.6 yr
Elasticity results for comparison with estimates given above: E(m) = 18.5%;
E(JS) = 34.7% (ratio = 1.87); E(AS) = 47.8% (ratio = 2.53). Cortés
(2002) predicts E(JS) < E(AS) whereas above estimates predict the reverse.