基于水声学的北江石角水库鱼类资源季节变动及行为特征研究

石角水库位于广东省北江清远水利枢纽和飞来峡水利枢纽之间,是北江干流第一座梯级电站河道型水库。由于水坝阻隔及其他人类涉水活动影响,库区渔业资源呈严重衰竭趋势。为了解其鱼类资源现状,采用分裂波束渔探仪EY60(120 k Hz,200 W)于2015—2016年对库区鱼类资源及种群行为特征进行调查评估。结果显示,鱼类密度、鱼类行为及垂直分布均存在明显的时空差异,且鱼类个体呈现小型化。2015年12月、2016年3月和2016年6月鱼类平均密度分别为(0.008±0.0125)ind/m3、(0.1601±0.1123)ind/m~3和(0.0405±0.0449)ind/m~3。不同季节鱼类密度存在显著差异(P0.05),冬春季节(12月、3月)鱼类主要集中于库首区域,夏季(6月)库尾为高密度区域。从垂直分布来看,鱼类主要分布于4~12 m水层,且不同区域间存在显著差异(P0.01)。不同季节鱼类洄游行为差异明显,具体表现为夏季鱼类主要从库首向库尾水平洄游,垂直方向为向下洄游,而冬季则相反。本研究初步探明石角水库鱼类资源分布及其行为特征,也表明声学方法在研究较大空间尺度鱼类行为方面的适用性,研究结果可为北江渔业资源管理与保护提供参考依据。

Seasonal variation of fish density and behavior in Shijiao Reservoir, Beijiang River by using hydroacoustic methods

Beijiang River, the second largest river of the Pearl River Basin, is an important species gene pool which has 143 species fish in datum. Shijiao reservoir is the first cascade river-type reservoir between Qingyuan hydro-junction and Feilaixia hydro-junction. Because of the blocking effect and other human activities, fishery resources had a declined tendency. Up to now, no relative research was reported in this area since the hydro-junction was built, so the actualities of fishery resource is unknown. To understand the current situation of fish resource, a split beam echosounder EY60 (120 kHz, 200 W) was used to survey the fish resource and behavior feature from 2015 to 2016 in different seasons. All the surveys were divided into a certain elementary distance sampling unit EDSU, so that for every survey, 200-250 EDSU with independent estimates of biomass, density and behavior were available. Echoview 4.9 was used to process acoustic data. The results show that there was significant difference in fish density, behavior feature in different survey periods and different survey areas. The average fish density in the survey area was (0.008±0.0125) ind/m³ in December 2015, (0.1601±0.1123) ind/m³ in March 2016 and (0.0405±0.0449) ind/m³ in June 2016 respectively. Fish individuals had evident seasonal variation tendency, characterized that fish mainly resided in dam area in winter and spring and migrated to upstream area in summer. According to the vertical distribution data, fish mainly distributed in 4-12 m layers and the distribution had significantly difference in different area (F=12.35, P<0.01). Fish''s behaviors such as swimming speed, swimming direction and depth preference were significantly different in different season. Take migration direction as examples, fish mainly migrated horizontally from dam area to upstream area and swimming down in vertical direction in summer, winter has opposite situation. As a whole, this study reveals a clear pattern of fish distribution, migration and behavior feature in different season, and shows the applicability of acoustic method to study fish behaviors in large scale area. The results can provide reference for fishery resources sustainable development and fishery engineering design of Beijiang River.