Trait-based analyses reveal the recovery of riverine fish communities after a fishing ban

Setting reserves or implementing fishing bans in certain areas has become a popular approach to enhance the recovery of disturbed populations and communities due to overfishing. Evaluating the effectiveness of such management measures primarily relies on taxonomic diversity, yet changes in taxonomy-based metrics may not be easily visible even in decadal periods. It has been suggested that functional diversity could outperform taxonomic diversity in capturing early signs of community changes following fishing bans. Here, using a before-and-after comparison methodology, we assessed the recovery of fish communities in the Chishui River basin, an important tributary of the Yangtze River, after seven years of implementation of the “10-year fishing ban” policy. Following the ban, fish community composition and abundance showed no significant changes, but biomass increased significantly. Taxonomic α-diversity (species richness, Simpson, and Margalef indices) and functional α-diversity (functional richness, imbalance, and dispersion indices), as well as taxonomic and functional β-diversity (including turnover and nestedness components), did not change significantly after the ban. Moreover, results from single-trait-based community-weighted mean (CWM) implied an initial recovery of fish communities after the ban, with a significant increase in CWM of maximum body length, age and length at first maturation, and lifespan, while CWM of growth rate showing a declining trend. This study provides a necessary empirical assessment of the efficiency of a fishing ban in restoring fisheries resources in freshwater ecosystems. Furthermore, single-trait-based functional diversity is a useful tool to detect early fish community changes, enabling a robust evaluation of conservation outcomes.