Spatial distribution and density changes of fish resources in East Dongting Lake during early fishing ban period

In order to find out the density distribution of fish resources in the East Dongting Lake during the early fishing ban period, and provide data support for the effect evaluation of the fishing ban and the protection of fishery resources, we conducted the hydroacoustic surveys in the central area of the East Dongting Lake and the Xiangjiang floodway from November 2 to 8, 2020. The results show that the average target strength of fish in the survey area was −46.48 dB; the average body length was about 18.66 cm, and the body length ranged from 1.63 to 113.50 cm. The difference of fish target intensity between the different regions was significant. The average fish density in all the survey segments was 150.20 ind.· (1 000 m³)⁻¹, ranging from 14.47 to 1 823.95 ind.· (1 000 m³)⁻¹. The average fish density in the East Dongting Lake was greater than that in the Xiangjiang floodway, and there were significant differences in the average density of fish among different regions (P<0.05), highest at the confluence of rivers and lakes. Compared with the survey data of the East Dongting Lake before the fishing ban (2015), the average target intensity of fish after the fishing ban decreased, while the average density of fish increased significantly (P<0.05).