Exploitable carrying capacity and potential biomass yield of sectors in the East China Sea, Yellow Sea, and East Sea/Sea of Japan large marine ecosystems

Abstract

Many fisheries resources in large marine ecosystems (LMEs) of Northeast Asia have become depleted due to overfishing, marine environmental degradation, and other unknown factors. In addition, the quality of coastal ecosystems has been degraded. Although a variety of approaches has been applied to improve the management of fisheries and to facilitate the recovery of depleted fisheries resources in Korea, they have not been wholly successful due to a lack of information on the history of fishing, exploitable biomass, and the current state of fisheries, compared to reference points, such as exploitable carrying capacity (ECC) and potential biomass yield (PBY). In this study, we reviewed the ECC and PBY of sectors in the East China Sea, Yellow Sea, and East Sea/Sea of Japan LMEs using the ecosystem modeling method (EMM) and holistic production method (HPM). EMM uses a mass-balanced ecosystem model, Ecopath with Ecosim, together with fishery catch and ecological data for each species group. HPM utilizes time-series catch and fishing effort data for all species combined. Estimates of the ECC for sectors in the East China Sea, Yellow Sea, and East Sea/Sea of Japan LMEs from these two approaches were similar with values 5.49–6.42 million metric tons (mmt), 1.35–1.36 mmt, and 1.42–1.81 mmt, respectively. Estimates of PBY were also similar for the two approaches with values 1.02–1.03 mmt for the East China Sea, 0.18–0.26 mmt for the Yellow Sea, and 0.27–0.34 mmt for the East Sea/Sea of Japan. The exploitable biomass began to decline from the early 1970s in the Yellow Sea and the mid-1970s in the East Sea/Sea of Japan and East China Sea, when over-fishing commenced. The current exploitable biomass for the LMEs are about 30–40% of those of the late 1960s. The ecosystem risk index (ERI) was highest for the Yellow Sea at 2.17, while the ERI was 1.95 for the East China Sea and 1.87 for the East Sea/Sea of Japan. Finally, we introduce a practical approach to achieve sustainable ecosystem-based fisheries assessment and management in LMEs, since most commercially important fisheries include species that migrate seasonally across the national boundaries of Korea, Japan, and China.