Current Situation And Management Countermeasures Of Fish Resources In The Qiantang River

Located in the northwestern part of Zhejiang Province,Qiantang River is the largest river in Zhejiang Province with a total length of 605 kilometers.The whole river is roughly divided into three river sections,Meicheng is upstream;Meicheng to Fuyang is the middle reaches;and Fuyang is downstream.The source of the Qiantang River in the north of Xin'anjiang River originates from the Xiuning County of Huizhou.From the beginning of the Majin River in the upper reaches of the Minjiang River in the south,the Nanyuan and Beiyuan to Meicheng intersections are injected into the Qilitun Valley of Fuchunjiang River,which flows to the Qiantang River and enters the East China Sea via Hangzhou Bay.The total basin area is 55,058 square kilometers.The characteristics of the sediment indicate that the upper reaches of Lanxi County and the upper reaches of Xin'an River are dominated by stones and pebbles;the pebbles on both sides of the Fuchunjiang Reservoir are densely muddy;the middle gorge is muddy;the dam from the dam to the Tonglu section has many pebbles and sand bottom;to Fuyang,Wenyu and Shasha Mud;the Hangzhou section is mostly fine sand.This survey was conducted on the fishery resources in the eight coastal areas from downstream to upstream from July 25 to August 3,2016.The results showed that a total of 96 species of catches,7 families,28 families,70 genera and 5 species were investigated.Fish 8 orders,19 families,57 genera,83 species,47 species of carp,71 species of migratory fish,6 species of freshwater fish.Compared with the previous period,the number of migratory fishes has decreased by more than a dozen,and the number of migratory fish has been greatly reduced.Previous investigations have shown that fishes etc.are the main economics of Qiantang River.Fish.Statistics show that more than 50%of the fish are small fish,while large fish,carp,grass carp,etc.are less than 10%.Due to the destruction of the habitat and breeding environment of large-scale economic fish,the population is reduced due to the pressure of over-fishing,which provides sufficient food and living space for small wild fish.The fishing intensity is too large,and the individual fishing is getting smaller.To make the reproductive community insufficiently supplemented.The catch exceeds the regenerative capacity of its population,resulting in a sharp decrease in the number of economic fish in the waters.The trend of individual miniaturization is obvious,and the body length and body weight data of the catch also show that the number of small fishes is increasing year by year.More than 50%of the fish are small fish,while large fish,carp,grass carp,etc.are less than 10%.The number of fish in the Qilitun dam is the highest,and it has been decreasing since then.The weight percentage shows the opposite.It first rises and then rises.The weight contribution of the central Tonglu and Fuyang is low.The number of fish in the lower reaches is small,but the weight contribution is high.It is related to the large catch of large fish in the downstream.In addition,it can be found that there are many fish in the Qilitun and the weight contribution is low.It is possible to capture more small fish here.It can be seen that on the dam,There are some differences in the downstream fish,indicating that the dam's barrier reduces the ecological diversity of the Fuyang section.Statistics show that the number of species,richness and dominance index in spring are slightly higher,and the diversity and evenness index in summer and autumn are higher,indicating that spring species are more abundant,and dominant fish are more obvious,in summer and autumn.The fish community has good stability and the fish composition between the communities is more uniform.For different river sections,the richness index,diversity index,and dominance index have obvious differences.The richness and diversity index are generally higher upstream,the second most important,and the lower one is lower,while the dominant index changes the opposite.In the middle reaches,the dominant fish species in the fish community are more obvious.It indicates that the fish communities in different sections have obvious differences.The fish protection and proliferation release should be determined according to the actual situation of the actual section.