Post-Fishing Ban Period: The Fish Diversity and Community Structure in the Poyang Lake Basin, Jiangxi Province, China

Between 2022 and 2023, four systematic fish surveys were carried out in the Poyang Lake basin (PLB), capturing 49,192 fish (7017 kg) and identifying 120 species from 10 orders, 21 families, and 70 genera. Cypriniformes were the most dominant, accounting for 79 species. The spring and autumn surveys collected 25,734 and 23,458 individuals, respectively, with corresponding biomasses of 3978 kg and 3038 kg. Dominant species (<i>IRI</i> > 1000) in the study area included <i>Hemiculter leucisculus</i>, <i>Megalobrama skolkovii</i>, <i>Hypophthalmichthys molitrix</i>, and <i>Aristichthys nobilis</i>. Additionally, critically endangered species such as <i>Ochetobius elongatus</i>, <i>Myxocyprinus asiaticus</i>, and <i>Acipenser sinensis</i> as well as exotic species like <i>Cirrhinus mrigala</i> and euryhaline species like <i>Cynoglossus gracilis</i> and <i>Hyporhamphus intermedius</i> were observed. Hierarchical clustering grouped the survey stations into three distinct areas (PYS, XBMS, and XBUS), with the ANOSIM analysis showing highly significant differences (R = 0.893, <i>p</i> < 0.01). Redundancy analysis (RDA) indicated that in spring, total phosphorus (TP) and temperature were the main factors influencing variability (80.50%), while in autumn, temperature, oil, and pH were the key factors (75.20%). This study emphasizes the predictable changes in fish community composition caused by environmental gradients and highlights the need for ongoing monitoring to effectively manage and protect the ecosystem, particularly in the post-fishing ban period.