Preliminary estimates of vital rates and population dynamics parameters of porbeagle shark in the western north Atlantic ocean
Vital rates and population dynamics parameters for use as inputs in stock assessment models were computed for the western North Atlantic population of porbeagle based on published biological information. Population dynamics parameters included maximum population growth rate (rmax), generation time ( A ), steepness of the Beverton-Holt stock-recruitment relationship (h), position of the inflection point of population growth curves (R), and spawning potential ratio at maximum excess recruitment (SPRMER). I used multiple methods to compute rmax: four age-aggregated methods and two age-structured methods. I used a Leslie matrix approach to incorporate uncertainty in growth parameters, maturity ogive, natural mortality, and lifespan. Productivity (rmax) was 0.046-0.059 yr-1for the six deterministic methods. For the stochastic Leslie matrix, mean values were: rmax = 0.051 yr-1(IQR=0.034 – 0.068), h = 0.36 (IQR=0.29 –0.43), R = 0.66 (IQR=0.61 – 0.73), A = 16.9 years (IQR=16.2 – 17.3), and SPRMER = 0.68 (IQR=0.58– 0.79). These estimates can be used to formulate informative priors in production and age-structured/integrated stock assessment models, to inform the time horizon for projections in all models, and for potential use in data-limited stock assessment approaches.