The Study On Community Structure Of Fish And Population Ecology Of Culter Dabryi In Lake Changhu

Lake Changhu,is located in the Yangtze River,Han River between the Jianghan Plain hinterland,which is the third largest lake in Hubei Province.Its water area of 140 square kilometers,the coastline of about 310 km,storage capacity of 271 million cubic meters,elevation in lake bottom is 28 meters,which is the highest terrain of the lake between Yangtze River,Hanjiang River.Since ancient times C hanghu is not only the gold waterway linked Jingmen,Shayang and Jingzhou,but also have flood discharge,irrigation,water supply and other functions.Lake is more abundant,lush vegetation,fish,shrimp,lotus root and other resources is very rich,is a variety of waterfowl natural habitat,but because of its cross-border lakes,management scattered,and since the 90's large area of the lake o f the fence breeding,water pollution and other factors caused by the diversity of fish in the lake diversity.Therefore,it is not only possible to describe the characteristics of fish community structure,but also to provide the basis for the research of future generations data.Changhu is a national protected species of aquatic germplasm resources,and the main protected species are Erythroculter ilishaeformis,Culter dabryi,Cultermongolicus,Culter oxycephaloides and Cultrichthys erythropterus.Culter dabryi is common species of Haizi Lake area and the Great Lakes region in Changhu Lake.So far,there are few reports on the research of Culter dabryi,and the content of population estimation and resource estimation is very few in the research report.In this study,the fishery resource survey was conducted in the four quarters of the lake from September 2015 to August 2016,and 592 samples of Culter dabryi were collected.The characteristics of the community structure,the age and growth of the larvae.,Breeding strategies,population parameters and resource content were studied.The main results are as follows:1.Fish community structure: a total of 61 species of C hanghu fish were identified in this survey,belonging to 7 orders,15 families and 43 genera.O f which Cypriniformes fish up to a total of 42 species,accounting for 68.9%,Compared with the investigation of fishery resources in Changhu Lake in the 1980 s,the species has been reduced.The dominant species of C hanghu dominant species had seasonal variation,and the relative importance index(IRI)of Pinkas(1971)was more than 1000,among which the Carassius auratus was the common dominant species in four seasons,and the dominant species were C yprinus carpio,C ultrichthys erythropterus,Pseudorasbora parva,C ulter dabryi,meal,Ctenopharyngodon idellus.C hanghu fish ecological types can be divided into lake settlement type,rivers and lakes migratory type,river type three,mainly to lake-based.According to the list of Changhu fish,the taxonomic diversity index ?+and?+ of C hanghu fish were calculated to be 59.1?521.6,and from different time scales analyzed the similarity coefficients of C hanghu,Dongting Lake,Poyang Lake,Taihu Lake and Xingkai Lake.The results showed that the similarity between Changhu and Dongting Lake fish community was the highest,C hanghu and Xingkai Lake similarity was the lowest.2.Age and growth: The age was identified as the material,and the rings on the scales were significant,and the markers were mainly dense and cut.The populat ion length of the species is about 71-388 mm and the weight range is 4.0-916.2 g.There were 7 age classes ranging 1 to 7 in the population,with prepondera nt age classes of 1-4 years old,which accounted for 91.38% of the total population.The relationship between body length and body weight was: W=5.632×10-6L3.148(n=592,R2=0.995,P<0.01),The t-test showed that there was no significant gender difference in body weight and length;the von Bertalanffy growth equation is: Lt=491.034[1-e-0.194(t +0.268)],Wt=1668.330[1-e-0.194(t +0.268)]3.148,The growth inflection point of the body weight was 5.64 years old,and its corresponding body length was 334 mm and body weight was 502.40 g.3.Breeding strategy: the odds ratio of male and female was 1: 1.28,and the minimum sexual maturity age was 2 years in both female and male.With the batch spawning type,the absolute fecundities of C.dabryi ranged from 15490 to 51078 eggs per fish,while the relative fecundities were from 87eggs/g to 532 eggs/g;The eggs of mature females were 0.45-0.86 mm in diameter.4.Population dynamics: the total death coefficient(Z)of C.dabryi was 0.80 / year;the natural death coefficient(M)was 0.42/year;the death coefficient(F)was 0.38/year in the fishing condition;the present exploitation rate was E = 0.48/year.According to the data of body length analysis,the amount resources of C.dabryi were estimated to be 1809710 individuals(15.18t)in 2015-2016 years.