基于水声学的长江上游向家坝至宜宾江段鱼类空间分布特征

摘要

To ascertain the spatial distribution characteristic of the fish which were below Xiangjiaba Dam with the length of 44 km, seven hydroacoustic surveys were conducted by using BioSonics DT -X echosounder in dryseason of January-April during 2006-2012 .Meanwhile hydraulic data were gained by using ADCP and capture surveys were carried out in March 2011.The results indicated as follows: (1) Twenty fishes were gained in the capture surveys .The standard length of fi-shes were from 10 cm to 30 cm with the mean of 21.31 cm.(2) The result of the hydroacoustic surveys showed that the mean target strength was (-42.32 ±5.02)dB and the mean length was 22.71 cm.(3) The fishes mostly distributed in the estuaries of Heng River , Jinsha River and Nanguang River , and the deep reaches of Datiewo and Lijiatuo , particular-ly.(4) Fishes chose the habitats where the velocity magnitude and Froude number were lower with deeper depth .%为了探明长江上游向家坝至宜宾44 km江段鱼类在枯水期（1-4月）的分布特征，2006-2012年期间采用裂波式探鱼仪BioSonics DT-X对该江段进行了7次水声学调查，并使用声学多普勒流速剖面仪（ ADCP）采集流速等环境特征数据，此外，还在2011年3月同期进行试验性捕捞。水声学探测目标（ Max．（ TSc）≥-45 dB）的平均强度为（-42.32±5.02） dB，推算平均体长为22.71 cm。试验性捕捞共采获20种鱼类，平均体长21.31 cm。鱼类在研究区域呈现聚集分布的特征，主要分布在横河口、岷江口、南广河口三处河口以及打铁窝、李家沱两处深水区。分析认为枯水期该江段鱼类对环境有一定的选择性，通常栖息在水体深、流速小且弗劳德数（ Fr）也较小的位置。