Influence Of The Jialing River’ Canalization On Spawning Grounds Of Major Commercial Fishes

The Jialing River is one of the main tributaries of the upper reaches of the Yangtze River.The Jialing River,from Lueyang,flows through Shaanxi Province,Gansu Province,Sichuan Province and Chongqing,and joins in the Yangtze River at Chaotianmen,Chongqing.The main stream has a total length of 1085 km and a basin area of about 160,000 km~2.It is divided into three sections,based on the geomorphologic features,the upper,the middle and the lower.The above of Zhaohua is the upper reache,Zhaohua to Hechuan is the middle reache,and Hechuan to Chongqing is the lower reache.From the upstream to the downstream,the Jialing River has many tributaries,forming a complex and diverse watershed environment with fertile water quality and abundant baits.It is a cradle for breeding fish,shrimp,shellfish,freshwater snails and other commercial aquatic products.In the 1950s,Planning and construction for the development and utilization of water conservancy,hydropower and shipping,along the Jialing River basin,were officially launched.From 1956 to 1960,the Chengdu Survey and Design Institute,Sichuan Water Conservancy and Sichuan Ministry of Communications completed the census and survey work of water conservancy resources in the Jialing River Basin.In the 1980s,the first water conservancy project of the Jialing River,the Mahui Water Conservatory Project,was built in Peng’an County.In 1992,the project was completed and connected to the Internet for power generation.At present,the channelization development of the main stream of the Jialing River has entered the final stage.With the construction of several water conservancy projects,great changes have taken place in the natural ecological environment of the Jialing River system,which also has a great impact on a variety of fish.To understand the current situation of the major commercial fishes’spawning grounds of the Jialing River,from March to April,2019,the spawning grounds of 1980’s 60 major commercial fish were investigated,to explore the Jialing River canalization influence on major commercial fishes’spawning grounds,to provide basic data for fish resources reasonable use and fish breeding protection in the Jialing River.The adaptability of Cyprinus carpio and Carassius auratus is strong,which can reproduce not only in the natural flowing water area,but also in the slow water reservoir river,and its resources have always Occupied an important positiont in the Jialing River’s fishery.In March to May,2019,the spawning grounds of Cyprinus carpio and Carassius auratus were investigated through Interview and site visit,from Guangyuan to Beibei,Chongqing,with the goal to understand the status of spawning grounds of Cyprinus carpio and Carassius auratus after canalization of the Jialing River.It provides basic data and reference for the follow-up research on the resource changes of Cyprinus carpio and Carassius auratus in Jialing River,also providing data support for analyzing the change of fish composition in the Jialing River and suporting reference for further analyzing the ecological impact of canalization in the Jialing River.The research results of this survey are as follows:1.At the end of the 20th century,the channelization project of the Guangyuan to Chongqing section of the main stream of the Jialing River officially entered the rapid development stage.Nowadays,15 aviation and power hubs have been built,including Shangshipan,Tingzikou and Cangxi,etc.The Lize aviation and power hub is under constructing,after its completion and operation,Guangyuan to Chongqing section of the16-level hub line was completed in the Jialing River.The 16 cascade power stations will be completed with a total investment of about 41.13 billion yuan,a total storage capacity of8.2062 billion m~3,a total installed capacity of 2.9671 million k W and an annual generating capacity of 10.299 billion k W·h.The total storage capacity under the normal water level is554.541 million m~3.The submerged tidal land totals 96035 mu.The channelized channel totals 653.4 km.The reservoir area is 402.63 km~2.The development mode of the power station is mainly riverbed development,and the regulation mode is mainly daily regulation,which has a strong ability to control the daily hydrological situation of the middle and lower reaches of the Jialing River,especially the discharge,velocity and water level,etc.2.The current situation of 1970’s 60 spawning grounds(43 in the main river,15 in the Dong River and 2 in the Xi River)was investigated in the middle and lower reaches of Jialing River,the Dong River and the Xi River,March to April,2019.The results of the survey are as follows:41 have disappeared,14 have existed but changed,and only 5 have remained basically unchanged of the 60 spawning grounds of the major commercial fishes.3.A total of 39 spawning grounds of Cyprinus carpio and Carassius auratus were investigated from Guangyuan,Sichuan province to Beibei,Chongqing,from March to May,2019.Including 3 in the Nan River,Guangyuan.29 in the middle and lower reaches of the Jialing River.4 in the Dong River and 3 in the Xi River.20 spawning grounds were newly investigated.Among them,the total area of 37 spawning grounds of Cyprinus carpio and Carassius auratus is about 487 hm~2,including Wanda Square Section,Wetland Park-Water Park and Huaxu Square,etc.And the distribution length of spawning grounds of Baixihao and Mumuhao is 21 km totally.The number,scale,type and distribution of the spawning grounds of the major commercial fishes have changed greatly,in the Jialing River.Due to the development of large-scale water conservancy and hydropower projects,the natural aquatic environment of the Jialing River has changed,and the hydrological regime,river form and bed quality have also changed greatly,which has adversely affected the natural breeding grounds of fishes.In addition,dredging sand and quarrying,shoreline development,weakened water self-purification ability and so on also cause harm to the spawning grounds of fish.The spawning grounds of Cyprinus carpio and Carassius auratus were mainly distributed in the middle reaches of Jialing River,followed by those in the lower reaches,and the least in the upper reaches.Spawning ground is generally located in the river broad shore area with shallow water,near the tributaries’entrance,the river sharply curved concave shore into the surrounding area of Tuo,the main stream forming Hao or Hao,river sandbar,etc.In the context of channelization,Cyprinus carpio,Carassius auratus and other fishes,which adapt to slow-flow and still-water habitats,still maintained a certain scale of breeding sites,which were less affected by channelization than those prefering rapid flow or turbulent rivers.