ASSESSMENT OF SEVERAL FISHING GEAR MANAGEMENT STRATEGIES ON ECONOMIC SPECIES YIELD AND BIOCOMMUNITY IN ZHOUSHAN FISHING GROUND FROM THE PERSPECTIVE OF MIXED FISHERIES

In order to explore the potential effects of different fishing gear fishing efforts on the economic and ecological benefits of fishery activities in mixed fisheries, the Size Spectrum Model (SSM) was constructed based on the fishing log data from four types of vessels operating in the Zhoushan fishing ground in 2022. The study evaluated the effects of changes in fishing methods on the yield, biomass, and community structure of each species in the mixed fishery. Thirteen fishing gear management scenarios were simulated, and the interannual variation trends in species yield under different scenarios were analyzed. Additionally, community responses to different levels of fishing activity were monitored using five ecological indicators: total community biomass, large fish index, mean weight, mean maximum weight, and size spectrum slope. The results showed that: (1) When trawling effort decreased, the total biomass, average body weight, and large fish resources increased significantly, particularly for Pampus argenteus, Lophiomus setigerus, and Larimichthys crocea. The yield of Lophiomus setigerus and Larimichthys crocea also increased significantly. (2) The total biomass of the community increased with the decrease of stow net fishing effort, leading to the recovery of Muraenesox spp., Collichthys lucidus, and Trichiurus lepturus. The yield of Muraenesox spp. increased significantly. On the contrary, as net fishing effort increased, the biomass resources and yield of the plum child decreased year by year. (3) When the fishing effort of the shrimp net decreased, the total yield and total biomass of the community decreased, while the resources of Solenocera spp. and Larimichthys crocea increased. When the fishing effort of shrimp net increased, the total production and biomass of community increased. (4) The change in gillnet fishing effort had little effect on fishery yield, biomass, and community structure. The research results provide important insights for the sustainable use of economic species resources in the Zhoushan fishing ground, and they can help managers better understand the potential impact of changes in fishing effort of various fishing gear on fishery output and community ecology, so as to formulate feasible and more effective fishery management strategies according to the importance of species and the actual situation of fishing vessels.