FISH COMMUNITY STRUCTURE AND ITS HISTORICAL CHANGES IN THE YUANSHUI RIVER OF THE MIDDLE REACHES OF THE YANGTZE RIVER DURING THE EARLY PERIOD OF THE FISHING BAN

In order to understand the structural characteristics and its historical changes in the Yuanshui River, located in the middle reaches of the Yangtze River, during the early period of the fishing ban, a fish resource survey was conducted at 7sampling stations between 2022 and 2023 using traditional fishing gear. A total of 120 fish species were collected and identified, which belonged to 9 orders, 19 families, and 68 genera. The largest group was Carpiformes, comprising 85species (70.83%). At the family-level, the most abundant group included 73species (60.83%). The dominant species were Plagiognathops microlepis, Squalidus argentatus, Aristichthys nobilis, Sinibrama wui, and Cyprinus carpio. In terms of ecological habits, resident species (53.33%), omnivorous (65.00%), and demersal fishes (43.33%) were predominant. Fish diversity indices varied among sampling sites, with greater seasonal variation observed in spring and summer compared to fall and winter. The community similarity and clustering analyses showed that the Yuanshui River fish community could be divided into four groups. Except for Jingzhou and Hongjiang, which exhibited moderate similarity, and the rest of the sites showed moderate dissimilarity. Compared with a previous fish survey in the ten years before the fishing ban (2010—2011), the number of indigenous fish species in Yuanshui River increased by 15species at the beginning of the fishing ban, including the frequent appearance of rare and endemic species such as Ochetobius elongatus, Onychostoma simum, Folifer brevifilis, and Decorus tungtin. In the fish community, the proportion of small-sized fish decreased and the proportion of the medium- and large-sized fish, both in terms of number and weight, increased. Additionally, the average weight of some common species showed a significant rise compared to pre-ban levels. The results of this survey suggest that the effect of the ten-year fishing ban in Yuanshui River are becoming apparent. However, there remains a gap when compared to fish resources from the 1970s and 1980s, and the impact of hydroelectricity developments along the Yuanshui River and other human activities still exist. This study provides a reference for the subsequent fishing ban, fish stocking and releasing programs, and fishery management efforts in Yuanshui River and Yangtze River Basin.