Demographic Analysis of the Pelagic stingray Pteroplatytrygon (Dasyatis) violacea (Bonaparte, 1832)
A) Using Captive data (Mollet et al. 2002)	B) Using guesstimates for field data
Age-at-first reproduction (α) 3 years ; Longevity (ω) about 10 years ,; Mortality, M = 0.4605 yr-1 (S = 0.6310) based on longevity of 10 years and using M = -ln(0.01)/10 ; Llitter of 6 every year, i.e. fecundity of 6/2 =3; Abar/α = 1.3 (using low value of range 1.3-1.5 because species is relatively short lived), thus Abar = 3.9 yr.	Age-at-first reproduction (α) 5 years ; Longevity (ω) about 15 years,; Mortality, M = 0.3070 yr-1 (S = 0.7356) based on longevity of 15 years and using M = -ln(0.01)15; Litter of 6 every year, i.e. fecundity of 6/2 =3; Abar/α = 1.3 (using low value of range 1.3-1.5 because species is relatively short lived), thus Abar = 6.5 yr.
Elasticities from α = 3 yr, Abar = 3.9 yr E(fertility) = E(m) = E1 = 1/Abar= 0.256; E(juvenile survival) = E(JS) = E2 = α *E1 = 0.769 (ratio ER2 = alpha = 3.0); E(adult survival) = E(AS) = E3 = 1 - E2 = 0.231 (ratio ER3 = Abar - α = 0.9); (E1 + E2 + E3 = 1.256); Normalized elasticities: E1 = 20.4%, E2 = 61.2%, E3 = 18.4%	Elasticities from α = 5 yr, Abar = 6.5 yr E(fertility) = E(m) = E1 = 1/Abar= 0.154; E(juvenile survival) = E(JS) = E2 =α * E1 = 0.769 (ratio ER2 = alpha = 5.0); E(adult survival) = E(AS) = E3 = 1 - E2 = 0.231 (ratio ER3 = Abar - α = 1.5); (E1 + E2 + E3 = 1.154); Normalized elasticities: E1 = 13.3%, E2 = 66.7%, E3 = 20.0%
Solution using life history table or 10x10 Leslie matrix (Mollet and Cailliet 2002) with alpha = 3 yr: Lambda = 1.1739, growth rate of stable population (r = ln (λ) = 0.1604 yr-1); Net reproductvie rate Ro = 1.9901, Generation "times": Abar = 4.105 yr (an age), T = ln(Ro)/r = 4.29 yr, μ1 = 4.50 yr (an age) (Abar/α = 1.368); Elasticities E1 = 0.2436, E2 = 0.7308 E3 = 0.2692 Normalized elasticites E1 = 19.6%, E2 = 58.8%, E3 = 21.7%.