禁渔初期东洞庭湖鱼类资源的空间分布与密度变化

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

为了摸清禁渔初期东洞庭湖鱼类资源密度分布情况,为禁渔效果评估和渔业资源保护提供数据支撑,于2020年11月2—8日对东洞庭湖中心湖区及湘江洪道进行水声学调查。结果表明,调查水域的鱼类平均目标强度为−46.48 dB,平均体长约为18.66 cm,体长范围为1.63~113.50 cm,不同区域间的鱼类目标强度存在显著性差异(P<0.05)。调查水域的鱼类平均密度为150.20尾·(1000 m^(3))^(−1),介于14.47~1823.95尾·(1000 m^(3))^(−1),湖区的鱼类平均密度大于洪道,不同区域间鱼类平均密度存在显著性差异(P<0.05),江湖交汇处的鱼类密度最高。对比东洞庭湖禁渔前(2015年)的调查数据,禁渔后的鱼类平均目标强度有所降低,而鱼类平均密度显著上升(P<0.05)。

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.·(1000 m^(3))^(−1),ranging from 14.47 to 1823.95 ind.·(1000 m^(3))^(−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).