Abstract:Fishing pressure and environmental factors can not only affect the abundance and distribution of fish, but also affect the age-and length-distributions. Length-based indicators of fish community are useful tools for fishery management. Based on the fishery resource survey data collected in the Haizhou Bay and its adjacent waters in spring and autumn from 2013 to 2022, seven length-based indicators including median length (L50), mean length (mL), 10th and 90th-percentile of the length distribution (L10, L90), mean length of the 10% largest fish (Lmax), large fish index (LFI) and size-diversity (SD) were analyzed to examine the dynamics of fish community structure in the Haizhou Bay as well as its response to the fishing pressure and environmental factors. The results showed that the robustness of L10, mL and L90 was better, and they were suitable for assessing the status of fish community in the Haizhou Bay. Random forest model results suggested that length-distributions of fish community in the Haizhou Bay were affected by a combination of fishing pressure and environmental factors. In terms of interannual variation, L10, L50 and mL showed a upward trend, while L90, Lmax and SD fluctuated, and LFI showed a declining trend, reflecting the recovery of small and medium-sized fish resources in the Haizhou Bay. However large-sized fish are still affected by fishing pressure, and more efforts should be made to protect and manage the fishery resources in Haizhou Bay. This study explored the potential of using body length-based indicators for setting fishery management objectives, which will help to gain a deeper understanding of the ecological status of fish community dynamics in the Haizhou Bay, and provide technical support for the protection and restoration of the Haizhou Bay fish community.