CHARACTERISTICS OF CHANGES IN FISH RESOURCES AND DISTRIBUTION PATTERN IN THE ANQING SECTION OF THE YANGTZE RIVER UNDER THE FISHING BAN

To evaluate the effectiveness of the fishing ban in the Anqing section of the Yangtze River, seasonal surveys of fish resources were conducted before and after the ban using a combination of hydroacoustic and net sampling methods. The results indicated that: (1) A total of 56 fish species were recorded, with an increase in species number, larger body size of dominant species, and higher diversity after the ban. (2) Fish density increased overall after the ban, being higher in all seasons compared to pre-ban levels, though the difference in summer was not significant (P>0.05). While all habitats experienced density increases, the most pronounced rise occurred in winter, reaching 2.2 to 4.1 times pre-ban levels. (3) The mean target strength increased after the ban, with a significant difference in spring (P<0.05); the proportion of high target strength range increased in autumn and winter. The mean total length of catches increased after the ban, with a significant difference in autumn (P<0.05), and the interquartile range of total length showed an expanding trend, indicating an increase in fish individual size. (4) After the ban, fish density and diversity followed a pattern of A>B>D>C, with significant resource increases observed in historically fished areas, such as the tail of Qingjie island and the estaury of the Wan River. The improvements in fish diversity, richness, and individual size demonstrate that the fishing ban in the Anqing section of the Yangtze River has achieved preliminary ecological effects. However, as the system is in a rapid recovery phase, continued long-term monitoring is essential. Furthermore, the spatial heterogeneity in fish richness and diversity suggests that differentiated management measures should be implemented for different habitats: priority protection should be given to the Qingjie island area and the estury of the Wan River and their natural shorelines, ecological restoration should be implemented for urbanized shorelines, and historically fished areas should be placed under strict control.