Evaluation of total allowable catch (TAC) based fishery resources management in Korea

Aim: This paper presents the efficiency and limitations of Total Allowable Catch (TAC) system, and it is intended to be used as basic research that suggests key directions of fishery resources management in Korea. Methodology: Two major fish stocks, common mackerel (Scomber japonicus) which is a TAC target species, and small yellow croaker (Larimichthys polyactis) which is a TAC non-target species were assessed to evaluate whether TAC target stock is effectively managed by the current TAC system. The current stock status was evaluated by estimating the biomass, yield per recruit (YPR) and spawning biomass per recruit (SBPR) at current fishing mortality (F) and age at first capture (tc) for TAC target species and non-target species. Since TAC is set based on acceptable biological catch (ABC), the biomass according to ABC change was predicted when TAC system is continued to apply. It was assumed to recover habitat, and YPR and SBPR according to the increase, and decrease scenarios of nautral mortality (M) and growth rate (K) were predicted. Results: The biomass trend of TAC target species was stable, and YPR and SBPR at current F and tc were similar with YPR and SBPR at optimal F. The biomass of TAC non-target species tended to decrease rapidly, and the estimated optimal F by YPR and SBPR models was 40-50% of the current F. The biomass of TAC non-target species according to ABC was predicted doubled within 10 years, however, both species did not exceed BMSY within the next 10 years. YPR and SBPR of both TAC target and non-target species increased more when the habitat was recovered than the current F and tc change. Interpretation: Fishery resources management by TAC system has a positive effect on the stock status, but, there was a limit to increase biomass above the target reference point level. If a species which is seriously low stock status, yield and spawning biomass were increased to adjust only F and tc. However, yield and spawning biomass of TAC target species was increased by only habitat recovery. And also, yield and spawning biomass of TAC target species were more increased when adjusted to optimal F and t in recovered habitat. Therefore, fisheries management will be more effective if TAC is a basic management tool and a holistic ecosystem approach considering various factors such as biodiversity, habitat quality, and socio-economic benefits, is considered.