Evaluación del abadejo (Genypterus blacodes) en el Atlántico Sudoccidental por medio de modelos de producción dinámicos.

Abstract

Two dynamic production models were applied to assess the status of ling Genypterus blacodes stock in the SW Atlantic. The simplest (biomass dynamic model)and a more complex one (structured production model) were fitted with commercial CPUEs as abundance indices. Ling is one of the most important demersal fishes in Argentine waters. It is a demersal fish found between 35°and 55°S that shows the highest concentration in summer, between 42°and 48°S. In winter, schools disperse over the whole range of distribution. Argentine ling fishery started developing in 1986 when catches surpassed 15000 mt/year to stabilize, in recent years, at around 23000 mt/year. The species is caught mainly as by-catch by trawlers with bottom net that direct their effort to hake Merluccius hubbsi. Although the stock is at its maximum biological production level (B98/k and B98r/kr0,5 and B98/Brms1), results from both models show a decrease of the resource. Present catch (~23400 mt)is 30. above the MSY estimated with the two models (~17500 mt). With present results, a collapse risk analysis was performed assuming three catch scenarios or constant effort: same as current (Cact-Fact), same as maximum sustainable yield (MSY)(Ccmp or Fcmp), and same as current situation plus a given quota for longliners. Risk analysis shows that, whatever the catch or effort assumption, the good state of the resource allows to envision collapse only as of the seventh year of projection. Collapse is highly probable in the long term because assumptions imply catches larger than the MSY. Risk is even higher when additional quotas to present catches are considered and lower when present TAC levels (19000 mt)are kept. The only strategy to reduce risk is to establish a TAC equal or lower than the estimated MSY. However, taking into account the imminent effort reduction in the common hake fishery and considering that ling is caught mainly as hake by-catch, it is feasible to keep the TAC at present levels in the short term. Unless recovery of ling as a consequence of effort reduction on hake is observed, to prevent risk enhancement, granting of additional quotas is not recommended.