Publication Abstract

An application of Bayesian approach to stock assessment model uncertainty

T.R. Hammond and C.M. O'Brien

The analysis of catch data from groundfish surveys (1985-1988) conducted on the Portuguese shelf and upper slope (20-500m) revealed five major geographic areas, each characterized by the presence of a typical fish assemblage. These areas of distinct fish assemblages were found to be closely aligned with depth, in a way that resembles spatial patterns previously described for other continental shelves in the North Atlantic. The sharpest biological transition on the Portuguese shelf takes place as one moves from areas shallower than 120m ("Shallow Groups") towards deeper locations offshore ("Deep Groups"). Beyond the 150m isobath, the biomass was dominated by blue whiting, whereas inshore variability in assemblage composition was much greater. Species such as sardine, horse mackerel, mackerel (to the north of Lisbon) and sparids (to the south) comprised significant and highly variable proportions of the population abundance inshore. There are similarities between the trophic and spatial organization of the marine community on the Portuguese shelf and that of other coastal upwelling ecosystems that are briefly reviewed here.

Reference:

T.R. Hammond and C.M. O'Brien, 2001. An application of Bayesian approach to stock assessment model uncertainty. ICES Journal of Marine Science, 58(3): 648-656