Characteristics of fish community structure and environmental driving factors in Taihu Lake during the first year of fishing ban.

ABSTRACT

Taihu Lake has officially implemented the full fishing ban policy since October 1, 2020. We investigated fish community of Taihu Lake in the four seasons of 2020. A total of 42 fish species were collected, belonging to 6 orders, 7 families, and 33 genera. The first five dominant species ranked by the index of relative importance were Coilia nasus, Toxabramis swinhonis, Hypophthalmichthys molitrix, Hypophthalmichthys nobilis, and Salangichthys tangkahkeii. The number of C. nasus accounted for 85.1% of the total number of catches. According to the distributional characteristics of cyanobacterial blooms and aquatic plants, Taihu Lake could be divided into the northern, central, and eastern regions. There was no significant difference in catch per unit effort (CPUE) among different lake regions, but Shannon diversity index and Pielou evenness index in the eastern region was greater than in the other two regions. The CPUE, Shannon diversity index, and Pielou evenness index were significantly different among the four seasons, with the lowest CPUE in autumn and higher diversity in autumn and winter than in spring and summer. Electrical conductivity, water depth, chloride, and transparency were the main environmental factors driving the seasonal variations of fish community in Taihu Lake, while electrical conductivity, dissolved oxygen, total alkalinity, and transparency were key variables driving the spatial patterns. The results could be used as the baseline data for fish community studies in Taihu Lake after the fishing ban.