Selective fishing of top predators further promotes the recovery of riverine fish resources

The decline of freshwater fish resources has become a global crisis, severely threatening food security and biodiversity in low-income regions. In response, China implemented a “ten-year fishing ban” across the entire Yangtze River Basin, making it one of the world's strictest conservation plans. However, the cascading effects of the ban on fish communities and food webs remain poorly understood, and the restoration outcomes for fish populations remain uncertain, with a lack of assessments regarding the potential impacts of fishing resumption. This study developed an Ecopath model for a typical river section under ban management and used the Ecosim model to simulate the dynamic changes in fish community and food web structure under different fishing strategies. The results show that the rapid increase in top predators after the ban triggers a trophic cascade detrimental to fish resource recovery, primarily through increased predation mortality, which leads to the decline of prey functional groups and limits the recovery of other functional groups. These findings contribute to the understanding and prediction of the impacts of fishing bans on community composition and food web processes. Furthermore, the prediction indicates that different fishing strategies after the ban result in distinct changes in fish communities and food web structures. Only the strategy of selectively fishing top predator functional groups can achieve further fish resource recovery, accompanied by increased food web stability. These results provide key insights for management aimed at restoring fishery resources.