| The section Wu zhou river is located in the upstream of Xi jiang river, the branchof the Pearl River, the junction of Gui jiang river and Xun jiang river. Its uniqueclimate, geography, hydrology, environment has not only provided a good shelter forhiding fish habitat, but also provided excellent venue for fish breeding. Theconstruction of hydropower stationimpacted spawning site, fatten site, winteringground and the migratory channel which was one of the reasons of the decline of fishstocks. The construction of Changzhou hydro-junction, made a block to theSemi-migratory and migratory fish, especially in breeding spawning season, a lot offish would gather here. Constructing fish passages has become an important approachto assist overcoming the adverse effects caused by such barriers This study includedtwo sections, using EY60echosounder to detect section of Wu zhou river and theChang zhou fishway, in order to analyze the demand of fish and propose theprotection strategy of Wu zhou section in Xi jiang river.Downstream river of Changzhou Dam was approved to a conservation zone in2009, it was the habitat of many commercial fishes such as Megalobrama terminalis,Spualiobarbus Curriculus, Cirrhinus molitorella, Elopichthys bambusa and so on.With the fish sampling, a split-beam echosounder (120KHz,250W) was used to theconservation zone and it’s lower area On May22to24,2010to understand theResources status. The results showed that The fish density was higher in the deepwater than shallow water, especially in concave region, fish had a obviousbehavior ofaggregation.; The fish mainly distributed in the depth of6-8m; The average fishdensity was (0.0730±0.1246)ind. m-3and the maximum density was0.5364ind. m-3;The average density of the center conservation zone was (0.1464±0.1559)ind m-3,the downstream section of conservation zone was(0.0176±0.032)ind m-3,average fish density of the center conservation was much higher thanthe other area. This shows that in the spawning season lots of fish had demand to sailupstream, because of the block of the dam, fish can only gather together in this sectionof river.Changzhou fish passage is the exclusivechannel for fish swimming upward to theupstream after the construction of the Chang zhou dam in the Pearl River, China.There was no scientific report on its fish pass effect so far. In this study, acousticsampling was conducted to understand the relationship between Target Strength (TS)distribution, fish density and the lure fish facilities (LFF)(run or stop). A200kHzsplit-beam echosounder (Simrad EY60) was used in a fixed location to assessthe sizeand timing offish migrations in Changzhou dam fish passage for four days in2012,combined with fish sampling. The results showed that with LFF stop, the average upstream fish density was729ind.h-1.m-2and the ratio of upstream fish anddownstream fish was2.11. In comparison, when theelectric fence was opened, afewfish moved downstream and the ratio of upstream fish and downstream fish was6.29,showing that the electric fence had obvious effect; The main time of fish swimmingthrough the fish passage was daytime, and at night the number of upstream fish anddownstream fish was nearly equal.Based on the above research, we propose the protection strategy:1) in fishspawning season, the study river had lots of fish, so each fishery administrativedepartment should strengthenlaw enforcement;2)in fish spawning season, the fishwaymust run to make sure there has a migratory passage;3) in view ofthe fish upstreamtime was in daytime, the information is crucial for managers to adjust the run mode offish passage to improve the efficiency;4) theelectric fence can help fish to findfishway easier, so it’s necessary to open the the electric fence to improve the fishpassage efficiency. |
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