Research On The Early Resources Of Drifting Egg Fish In The Intersection Of The Jinsha River And The Yalong River

The Yalong River merged into the Jinsha River in the Yinjiang section of Panzhihua,forming a complex ecological functional zone with different environment conditions.The Panzhihua section of the Jinsha River is located in the middle reaches of the Jinsha River,which is a canyon rapids habitat.It is a transitional area between the fish of the Qinghai-Tibet Plateau and the fish in the river plains,where the fish stocks are abundant.The Yalong River is the largest tributary of the Jinsha River and its estuary section is a transitional area connecting the Jinsha River and the Yalong River.In the intersection of the Jinsha River and the Yalong River,there are many kinds of endemic fishes and indigenous fishes in the upper reaches of the Yangtze River,such as,Coreius guichenoti,Leptobotia elongata,Percocypris pingi,Rhinogobio ventralis,Schizothorax kozlovi,Schizothorax dolichonema,etc.At the same time,the basin also has abundant water with concentrated fall and abundant hydropower resources.The Jinsha River is a large-scale hydropower base planned in China.There are 27 cascade hydropower stations in the whole basin,of which 3 are located in the Panzhihua section,namely Guanyin Yan,Jinsha and Yinjiang hydropower stations.The Yalong River is the third largest hydropower base planned in China.21 cascade hydropower stations in the whole basin and 5 hydropower stations in the downstream were planed to develop,all of which have been put into operation.Hydropower stations have brought about certain adverse effects on the ecological environment and fishery resources in the basin while bringing wonderful social benefits,which can cause significant changes of the hydrological situation in the river and have a greater impact on the habitat conditions of fish.This study carried out on a survey about the fishes of early life history stage in the Panzhihua section of the Jinsha River and the estuary of the Yalong River from June to July in 2016-2018.The status for early fish resouces of drifting eggs was analyzed in the estuary area of the Jinsha River and Yalong River based on the survey data of three years.The main findings were as follows:1.During the three-year survey period of 2016-2018,696 eggs were collected in the intersection of the Jinsha River and the Yalong River.Among them,478 eggs were collected from Panzhihua section of Jinsha River,belonging to 2 orders,4 families and 8 species.Cobitidae and Balitoridae had the same number of species,each of which had 3 species,accounting for 37.5%each.The number of species of Cyprinidae and Sisoridae was also the same,accounting for 12.5%each.There were 7 species of drifting egg fish,accounting for 87.5%of the species all,including 5 species of endemic fish in the upper reaches of the Yangtze River,which were Coreius guichenoti,Leptobotia elongata,Leptobotia rubrilabri,Jinshaia sinensis and Jinshaia abbreviate.In the estuary of the Yalong River,218 eggs were collected,belonging to2 orders,4 families and 7 species.There were three species of Balitoridae,accounting for 42.9%of the total number of species,followed by the Cobitidae,2 species,accounting for 28.6%,and 1 species of Sisoridae,accounting for 12.5%.There were 5species of drifting egg fishes,accounting for 75.0%of all,of which 3 species are endemic fish in the upper reaches of the Yangtze River,namely Leptobotia elongata,Jinshaia sinensis and Jinshaia abbreviate.2.It was estimated that the total number of fish eggs flowing through the Panzhihua section of the Jinsha River from June to July in 2016-2018 were 24.62×10~6ind,28.10×10~6 ind and 41.57×10~6 ind,of which the total number of eggs of the endemic fish in the upper reaches of the Yangtze River were 7.74×10~6 ind,9.41×10~6ind and 9.42×10~6 ind,respectively.There were 3.50×10~6 ind,13.78×10~6 ind and3.87×10~6 ind fish eggs flowing through the estuary of the Yalong River from 2016 to2018,respectively.The eggs of endemic fish in the upper reaches of the Yangtze River eggs was 10.61×10~6 ind in all.3.During the three-year survey from 2016 to 2018,the total number of fish eggs of Leptobotia elongata in the Panzhihua section of the Jinsha River was 2.09×10~6 ind,6.86×10~6 ind and 6.03×10~6 ind,respectively.The Coreius guichenoti was only found in 2018 which was 0.23×10~6 ind.The Leptobotia elongata was collected only in 2017in the estuary of Yalong River and the total number of fish eggs was 0.20×10~6 ind.The total number of eggs of Jinshaia sinensi was 1.20×10~6 ind,1.03×10~6 ind.and5.60×10~6 ind,respectively.4.There was a certain time difference in the reproduction of fish in the intersection of the Jinsha River and the Yalong River during the survey.The breeding period of the same fish in the two rivers was also different.The fish breeding peak in the Panzhihua section of the Jinsha River was from late June to early July.The breeding period of Lepturichthys fimbriata,Jinshaia sinensis and Jinshaia abbreviat was from mid-June to July,and the breeding peak of Lepturichthys fimbriata was from late June to early July.The breeding period of Leptobotia elongata and Botia superciliaris was from late June to July,lagged behind,of which the breeding peak of Botia superciliaris was from late June to early July.The Coreius guichenoti breed in early July.The majority of fishes in the estuary of the Yalong River were mainly concentrated in June,and the breeding peak was mid-to-late in June.Jinshaia sinensis and Lepturichthys fimbriata had a large advantage during the whole investigation period and the Jinshaia sinensi mainly appeared in June.The Leptobotia elongata appeared in the middle and early July of 2017,and the Botia superciliaris appeared in the late June of 2016.5.It was estimated that there were four spawning grounds in the Panzhihua section of the Jinsha River by data analysis from 2016 to 2018,which were Panzhihua East District,Panzhihua West District,Geliping Town and Guanyinyan in Panzhihua.Among them,Panzhihua East District had the largest spawning scale with a cumulative spawning of 71.90×10~6 ind,accounting for 87.7%of the total spawning scale.In the estuary of the Yalong River,there were mainly two spawning grounds,concluding Yanbian County in Panzhihua and Deshi Town in Panzhihua,of which Yanbian County had a larger spawning scale and the total spawning scale of three years was 12.70×10~6 ind,accounting for 66.3%of the two spawning grounds.