A Study On Integrated Technology Of Ecological Fisheries In Chenghu Lake

Chenghu Lake is in the water network zone which is in east of Taihu Lake and northwest of DianShan Lake. Chenghu Lake is located in E120°41′, N31°22′. The length of Chenghu Lake is more than 20km, the shape is triangle, the area is 40km2, the average depth is1.83m, the volume is 0.073 billion m3. In recent years, Chenghu Lake presented eutrophication phenomenon, and aquatic vegetation, stability of lake and ecosystem was destroyed, water quality was deteriorated for the rapid development of economy of surrounding area and the elevation of living standard. The some excellent local wild fish and shell resource has decreased even dead out for the eutrophication and pollution.We have investigated the water chemistry and aquatic community structure, and researched the relationship between the adjustment of fish culture structure of Chenghu Lake and the change of water quality preliminary in this stduy. Simultaneously, we researched the technology of chub fries culture and the relationship of this technology and water quality in production practice. We hope that this study would provide some basic in order to improve water quality of Chenghu Lake, and some reference for the further development of Chenghu Lake fisheries. The main results are listed below:1.The results revealed that the eutrophication of Chenghu Lake was reducing in 2002 to 2009. SD was increased from 45.5 cm of 2002 to 60.4cm; DO was remained in more than 8mg/L except 2004; TP was decreased from 0.16mg/L to 0.09mg/L, reduced 43.8%; TN was decreased from 2.34mg/L to 1.55mg/L, reduced 33.8%; Chla was reduced from 51.3μg/L to 34.4μg/L.Phytoplankton of Chenghu Lake contains 72 genus in 7 phylum. 29 genus of chlorophyta, 15 genus of bacillariophyta, 15 genus of cyanophyta, 4 genus of xanthophyta, 4 genus of pyrrophyta, 1 genus of euglenophyta in the 72 genus. The most is chlorophyta, then bacillariophyta and cyanophyta. Dominant species are chlamydomnas ssp, chlorella vulgaris beij, cosnarium sp, centritrotundatus sp, gonyostomum depressum and melosira sp.The result of fishes resources told that 63 fishes were collected in 9 order, 16 family, 45genus, which can be divided into 4 floras.2.The results revealed that TP, TN and Chla decreased and SD increased with the ascent of chubs output and the drop of bighead carps output. The output of chubs showed a positive correlation with SD(R2=0.5428); the output of bighead carps showed a negative correlation with SD(R2=0.4932).3.We used the method of natural resources proliferation in key and fries culture in secondary. We cultured fries in the pollution water outfall without feeding. This technology can increase the survival rate and recapture rate. At the same time, water quality can be improved.