Publication Abstract

Bayesian assessment of NE Atlantic spurdog using a stock production model, with prior for maximum population growth rate set by demographic methods

Bayesian assessment of NE Atlantic spurdog using a stock production model, with prior for maximum population growth rate set by demographic methods

T.R. Hammond, and J.R. Ellis

Schaefer-model stock assessments can be biased and imprecise because they are fitted to catch rate data (CPUE). However, consideration of life history constraints can improve parameter estimates by shedding light on maximum productivity. Therefore, we applied the methods of McAllister et al. (2001) to North-East Atlantic spurdog (Squalus acanthias) by using demographic techniques to convert prior distributions for age-specific fecundity and natural mortality (the latter based on tagging data and assumed constant) to prior distributions for the maximum rate of population growth (r). The priors for r generated in this manner were then used in a Bayesian, Schaefer-model assessment of spurdog, fitted to IBTS survey CPUE data. Thus, assessment results were coherent with life-history constraints; they also suggest the stock is depleted to about 5% of virgin biomass.

Reference:

T.R. Hammond, and J.R. Ellis (2005) Bayesian assessment of NE Atlantic spurdog using a stock production model, with prior for maximum population growth rate set by demographic methods. Journal of Northwest Atlantic Fisheries Science, 35: 299-308

T.R. Hammond*, and J.R. Ellis*

Journal of Northwest Atlantic Fisheries Science, 35: 299-308