An extensive assessment of exploitation indicators for multispecies fisheries in the South China Sea to inform more practical and precise management in China

Abstract

China is the largest producer of marine capture fisheries globally. Overfishing since the 1970s has led to a decline in fishery resources in Chinese coastal waters. After China’s reform and opening up, a series of management measures were implemented to alleviate marine fishing pressure and conserve the fisheries resources. We conducted a comprehensive assessment for multispecies fisheries in the South China Sea (SCS) to explore whether fisheries management has been effective in recovery of the resources. Indicators of the exploitation status of major commercial fish species were assessed using statistical catch data and survey data simultaneously. The results reveal a significant shift in bottom-trawl fishery, with its share of the total catch transitioning from an upward to a currently downward trend. The species composition of bottom-trawl fisheries has undergone substantial changes in the SCS over six decades. Stock assessment results based on catch data indicated some positive signals, with small pelagic fishes, such as herrings, anchovies, mackerel and scad recovering from overfished/overfishing to a healthy status. However, the exploitation status of high-trophic-level fish species, such as conger pike and groupers, were still in overfished status. Assessment based on length data was less optimistic. Our uncertainty analysis showed that the catch-based model is less sensitive to parameters compared with the two length-based models considered here. We advocate for more practical and precise fisheries management in China, such as category/species-based management, further optimization and improvement of the fishing structure, development of a scientific quota-based system, ecosystem management that incorporates climate factors, and establishment of marine protected areas for fish species that are severely overfished or have high ecological value.