Research On Age Structure And Species Diversity Of Major Economic Fish In Xingkai Lake

May, July and September in 2007, we established four fish monitoring stations (including Long Wang temple, Ba liwa, New kailiu and Dangbi town) in Xingkai Lake to learn fish field of sails and identify the fish species. In fish age structure, the identification material was fish scales and fishing nets was the three-linked network set. In this paper, the aim was to research the age structure and community species diversity of major economic fish in Xingkai Lake. At the same time, we illustrated growth trait of major economic fish and characteristics of community structure in Xingkai Lake, that will help to optimize the fish community structure, and rationally use fish resources and improve economic efficiency of lakes.Fish fauna was surveyed and identified. A total of 41 species were found, belonging to 6 orders, 11 families 35 genera, of which Cypriniformes Cyprinidae were largest, accounting for 65.85% , which were the main categories of fish fauna composition in Xingkai Lake. Fish fauna components of Xingkai Lake were complex, belonging to the Tertiary Flora , the Arctic freshwater fauna, the northern plains flora, fauna in the northern mountains, rivers and plains flora, fauna of subtropical plains in six fish fauna complex, of which the river plain fish fauna was most complex types, there are 20 kinds, accounting for 48.78% of all types.In Xingkai Lake, the fish yield decreased obviously. The amount of fishing was approximately kiloton in 1980s, but was 415t in 2007 (reduction above 60%). The amount of Erythroculter ilishaeformis accounted for 9.6% of the total fish production. So, the valuable fish resources (Erythroculter ilishaeformis) have been severely damaged.The major fish fields of catch composition were Hemiculter leucisculus and Hemiculter bleekeri Lucidus in Xingkai Lake. The miniaturization trend of fish resource was becoming obvious. By researching age structure of 11 major economic fishes, except for Protosalanx hyalocraniah, the other 10 kinds of fish are in the age composition of age 1 to 3 fish-based, and slow growth..By the analysis of the relationship between fish body weight and fish body length of 11 major economic fishes, indicating that the body weight of these types of fish is proportional to the cubic of body length, belonging to the type of symmetrical growth.With testing and fitting, the rule of growth and change was reflected in Von Bertalanffy Growth Equation (including Erythroculter ilishaeformis, Erythroculter dabryi shinkainensis and Culter erythropterus Basilewsky).The equations were as follows:Erythroculter ilishaeformis:(?) Erythroculter dabryi shinkainensis:(?)Culter erythropterus Basilewsky: (?)The species diversity was lower in Xingkai Lake. The research showed Shannon-Weaver index (HA) to 1.11; Wilhm improvement index (HB) to 1.65; Simpson index (S) to 0.42; Pielon evenness index respectively JA: 0.27, JB: 0.40 and JS: 0.10,3 species diversity index and evenness index were lower.We learned there were 7 dominant species according to the division of fish dominant species (>1000) in Xingkai Lake. The dominance of Hemiculter leucisculus was the biggest. In dominant sequence, the order was Hemiculter bleekeri Lucidus, Erythroculter ilishaeformis, Erythroculter dabryi shinkainensis, Pelteobagrus fulvidraco, Pelteobagrus nitidus and Culter erythropterus Basilewsky. Accounting for 17.1% of total species, 92.5% of community amount and 86.4% of community weight.