CHARACTERISTICS AND CHANGES OF FISH DISTRIBUTION IN THE MAINSTEM OF THE THREE GORGES RESERVOIR DURING THE EARLY STAGE OF THE TEN-YEAR FISHING BAN
In order to understand the characteristics of fish distribution in the mainstem of the Three Gorges Reservoir during the early stage of the Ten-Year Fishing Ban,hydroacoustic surveys were conducted during both the breeding and overwintering seasons in 2023,along with simultaneous catch surveys.The hydroacoustic survey results showed that the mean fish density during the breeding and overwintering periods was(5.52±10.43)and(3.26±5.60)ind./1000 m3,respectively,with no significant difference(P＞0.05),and the average target strength of fish was(-59.79±1.95)and(-56.51±2.88)dB,respectively,with a very significant difference(P＜0.01).It was estimated that the fish body length ranged from 1.24 to 156.68 cm with an average of 4.03 cm in the breeding period and from 1.25 to 155.96 cm with an average of 9.01 cm in the overwintering period.Fish densities detected by the two hydroacoustic surveys were not significantly different horizontally.Vertically,over 85% of the fish in both surveys were distributed in water depths from 0 to 30 m,and the fish target strength showed a pattern of gradual increase with increasing water depth.Catch surveys revealed that small individual fish such as Hemiculter leucisculus,Pseudobrama simoni,and Saurogobio dabryi dominated the Three Gorges Reservoir area,and the exotic species Coilia brachygnathus comprising a rela-tively high proportion of the catch.Compared to the 175 m impoundment,the distribution characteristics of fish resources in this survey did not change significantly,however,the average target strength increased,and the trend of fish miniaturization was curbed.This study preliminarily reveals the spatial and temporal distribution characteristics of fish resources in the Three Gorges Reservoir and their changes following the fishing ban.It accumulates research mate-rials on fish resources at the early stage of the ban and provides basic data reference for evaluating the effect of the Ten-Year Fishing Ban in the Yangtze River.
Early stage of fishing banthe Three Gorges ReservoirVarious periodsHydroacousticsSpatial and temporal distribution of fish
万方数据
维普
