Fish Diversity and Environmental Relationships in the Jinsha River During the Initial Phases of the 10-Year Fishing Ban: A Metabarcoding Approach.

Fish diversity is essential for maintaining the balance of aquatic ecosystems, particularly in rivers impacted by overfishing and hydropower projects, such as the Jinsha river, the upstream segment of the Yangtze river. During initial phases (August and November, 2023) of the 10-year fishing ban in the Yangtze river basin, we investigated fish diversity, seasonal variations, and their correlation with environmental factors in the Jinsha river using environmental DNA (eDNA) metabarcoding. Utilizing two pairs of 12S rRNA primers, MiFish-U and AcMDB07, we identified 61 fish species across 5 orders, 17 families, and 52 genera, including 4 national protected and 7 invasive alien fish. Among them, Cypriniformes constituted the predominant group within the fish community, accounting for 65.6%. This finding aligns with the results from a recent fish catch study, which recorded 68 species of fish belonging to 4 orders, 15 families, and 48 genera, including 4 national protected species and 8 invasive alien fish. The alpha diversity analysis revealed compositional differences in the fish community across various regions and seasons. Furthermore, key environmental factors, such as water temperature, dissolved oxygen, nitrate nitrogen, total suspended solids, and conductivity, were found to be highly correlated with fish diversity in the Jinsha river. Consequently, we provided detailed seasonal data on fish diversity and its correlations with environmental factors, which will aid in the systematic management and restoration of fisheries and the assessment of the 10-year fishing ban in the Jinsha river.