Study on the diversity of fish community structure and growth performance of Hypophthalmichthys molitrix and Aristichthys nobilis in Yankou Reservoir, Zhejiang Province

Abstract:

The investigation on fish resources in Yankou reservoir was carried out in March, May, July, September, November 2013 separately, in order to reveal the characterization of fish community, resources status and growth performance of main fish species.452 fish specimens were measured and identified, which belonged to 5 orders,8 families and 37 species.Cyprinidae was the largest order,which accounted for 75.7% . Siluriformes accounted for 13.5%, and Perciformes accounted for 5.4%. Salmoniformes and synbranchiformes accounted for 2.7%,respectively.The ecological type analysis revealed that the community was dominated by carnivorous and omnivorous fish. There were 5 dominant fishes by analyzing the index of relative importance, which were Hypophthalmichthys molitrix, Aristichthys nobilis, Hemiculterlla wui, Culter alburnus and Distoechodon tumirostris. Three diversity indexes including species richness index(D),Shannon-Wiener index(H') and species evenness index(J') were used to analyze diversity characteristics of the fish community. And the values of D,H' and J' varied from 2.09 to 6.05,0.87 to 1.42 and 0.41 to 0.92 respectively.The growth equation of body length and weight for H. molitrix were L_t=73.591[1-e^{-0.265(t+0.136)}] and W_t=5.911[1-e^{-0.265(t+0.136)}]^2.812, respectively; and for A.nobilis were L_t=73.256[1-e^{-0.318(t+0.12)}]and W_t=7.625[1-e^{-0.319(t+0.012)}]^3.07, respectively. In Yankou reservoir, Hypophthalmichthys molitrix and Aristichthys nobilis grew relatively fast from 1 to 4 years, and their inflecting point were 3.795 and 3.327,respectively. The most appropriate catching age was 5 years for the two aquatic environmental protection oriented fishes in order to get the best effect on algal bloom control and economic benefit.