A study on the ABC estimation approach for the ecosystem-based TAC management

Abstract

The Korean ABC for TAC management has been estimated by a five-tier system that relies on population-based stock assessment models according to available ecological information for pelagic or demersal species. To overcome the limitations of the current ABC estimation system based on population dynamic models. This study attempted to integrate the ecosystem-based fisheries assessment (EBFA) approach into the current Korean ABC estimation system, and has developed the ABC estimation approach for ecosystem-based TAC management. To estimate the ecosystem-based ABC, the ABC estimated by the current ABC estimation system was adjusted depending on the species risk index (SRI) that was derived from risk analysis of the EBFA. In this process, the SRI-F model that generalized the relationship between the SRI and fishing mortality (F) was devised, and it was used to estimate the ecosystem-based ABC. Also, the SRI projection as a function of the F scenario was conducted to estimate the regression coefficients of the SRI-F model. The ecosystem-based ABC estimation system was demonstrated by applying it to the chub mackerel, one of the TAC species in Korea, by large purse seine fishery. The SRI-F model was obtained, SRI0=0.565; b=1.617, and showed the statistically significant level (p<0.001 and R2=0.885). The SRI of 2004 was estimated at 1.06, and the ABC was adjusted from 180,000 mt to 168,520 mt (-0.8%). It was found that this approach can be used to allocate the TAC in an ecosystem context for quota-managed fisheries.