赤水河下游鱼类资源时空分布特征OA

Seasonal hydroacoustic surveys combined with net fishing data were used to investigate the spatiotemporal distribution of fish resources in the lower Chishui River in 2023.The results revealed that the fish communities were predominantly composed of demersal species such as Squalidus argentatus,Pelteobagrus vachelli,Pseudobrama simoni and Spinibarbus sinensis.Significant variations in the composition of the fish communities were observed between the Chishui and Hejiang reaches.The highest net fish-ing density was observed in the waters around Xianshi Town and Qiejiaoya.Hydroacoustic results showed that the mean target strength(TS)of the fish was-56.43 dB,-58.83 dB,-61.14 dB and-57.37 dB respectively,with an estimated mean total length of 12.1 cm,6.1 cm,5.5 cm and 8.1 cm respectively.This showed a trend of February＞October＞June＞August.Fur-thermore,temporal variation in fish density was observed,with the highest mean density(10.61 ind./1000 m3)in June,followed by August(8.80 ind./1000 m3),October(5.07 ind./1000 m3)and February(1.65 ind./1000 m3).The horizontal distribu-tion showed higher densities in Zhenlong,Xianshi,and Fuxing towns,with average densities of 16.12,21.16,and 17.46 ind./1000 m3,respectively.In terms of vertical distribution,fish density was primarily concentrated in the lower layers.ArcGIS spatial statistical analysis estimated fish resources to range from 5.3 t in August to 12.1 t in February,exhibiting a patchy distribution re-lated to water depth and channel morphology.Compared to historical data,our results indicated an initial recovery of fish communi-ties following the implementation of the"10-year fishing ban"policy in the Chishui River.We recommend integrating acoustic methods into routine fish resource monitoring.