3 1, suitable for the growth and reproduction of aquatic plants and fish. Spewing lake area 164km2, average water depth 1. 27m, storage capacity 1575 x 10sm3. Huyong Lake is a shallow dish-shaped depression with a flat bottom. It is one of the remaining lakes of Taihu Lake differentiation, and many rivers are connected with Taihu Lake. Huyong Lake is also a typical grass lake, and the coverage rate of aquatic plants is 93% ~ 95%. In addition to fish culture area, submerged plants account for more than 85% in the lake network.
The main aquatic plants are yellow silk grass, POTAMOGETON malayi, POTAMOGETON crispus, Valeriana angustifolia, Haematococcus verticillata, Ceratophyllum and Rhododendron. Due to the continuous expansion of aquaculture area around the lake network, a large number of aquatic plants and artificial exogenous feeding were caught, which accelerated the process of aquatic vegetation degradation and eutrophication, thus affecting the play of various functions of the lake. In order to promote the healthy development of fishery production and the continuous improvement of ecological environment, it will be the main contents of the Eighth Five-Year Plan to establish a high-yield fishery model and develop ecological fishery in Hu Yong.
Its guiding ideology is: firstly, Yong Lake is regarded as a unified compound fishery ecosystem. On the basis of overall consideration of the combination of current and long-term interests, according to the natural conditions and bait resources in different areas of the lake, the whole lake is divided into three ecological areas with different functions, and different aquaculture techniques and protection measures are adopted to obtain more catches and economic benefits on the premise of ensuring that the environmental quality of the lake is not degraded and the biological resources are not destroyed.
Secondly, the species structure of cultured fish and the structure of aquatic plant community are adjusted to save bait resources and optimize aquatic plant community, so that aquatic plant resources can be continuously utilized and the water environment can be continuously improved. Therefore, the eco-fishery model of the lake can be divided into three ecological zones and two structural adjustments. The construction of three ecological culture areas is resource proliferation area, culture protection area and net enclosure culture area; The two structural adjustments are to optimize the community structure of aquatic plants and to adjust the fish structure.
Since the "Eighth Five-Year Plan", the fishery production in Huyong Lake has gradually embarked on the road of combining culture and capture by vigorously developing large-scale water net enclosure culture, especially after implementing ecological fishery projects in three ecological areas and taking measures such as adjusting the population structure of cultured fish and optimizing the community structure of aquatic plants, the fishery production in Yuhu Lake has been significantly improved, the aquatic plant community has been optimized, and the water quality has remained in a good state, achieving obvious economic, social and environmental benefits.
1994 aquaculture output reached 9 137. 8t, adding 1992. 1% ; The total output value reached 92 illusions. 80,000 yuan, 76% more than 1.992. 4% ; The output value per hectare is 30067 yuan, 60% higher than that of 1992. 5%。 The output of famous, special and excellent aquatic products has increased significantly, and the economic benefits have improved significantly. From 1992 to 1994, the average annual catch of freshwater shrimp is 1054.
7 tons, accounting for 53. 54%, a net increase of 344 compared with 1990. 5 tons, a year-on-year increase of 48. 5%。 Among them, the output of 1993 is 960. 2 tons, accounting for 5 1 of the fishing output in that year. 8%, accounting for 84. 77%。