| The lake is an important part of terrestrial ecosystem. Most of the lakes are provided with water delivery, water storage, cultivation and irrigation and other ecological functions. As people’s access to the natural base of the aquatic products, the lake also plays a pivotal role in fishery production. In recent decades, especially after the construction of the Three Gorges Project, great changes have taken place in the Yangtze River basin ecological environment. The miniaturization and younger age phenomenon of fish resources in lakes in the middle and lower reaches of the Yangtze River is very obvious. The composition of the fish community structure also changed. Overfishing has caused decline of fish resources, rivers and lakes barrier makes the semi-migratory fish disappear gradually, the fish resources and diversity in a large number of lakes are decreasing. Therefore, the study of the Dongting Lake fish community etc will enrich the fish community ecological contents of the middle and lower reaches of the Yangtze River lakes, and estimated future prospects of fish resources from the characteristics and community structure of fish stocks. Put forward tangiblefeasible and effective ecological environment and fish resources protection and management measures.Consequently, Dongting Lake, was selected as target water, a monthly investigation on fish diversity was carried out in March-December,2004. Four sampling areas were located along a transect from the Yangtze mainstream to the lake center, i.e. Chenglinji, East Dongting Lake, West Dongting Lake and South Dongting Lake. Community structure of fishery resources of Dongting lake was studied and the biology of main economic species was also systematically studied, providing the comprehensive management of the Dongting Lake and its watershed connectivity and providing accurate data and measures to create a "healthy" lake. The main results are given as follows:1. Totally85fish species belonging to9orders,17families and48genera were recorded. In terms of species number, cypriniformes was the richest in each region accounting for64.29-70.00%of the total. Among them, Cyprinids were the largest group, accounting for58.8%of the total. Campared with several historical surveys, the number of species was dramatically declined, but more than survey in2008.2. Fishery resources in Dongting Lake decay. Compared to1963, the survey of ecological type of fishes in Dongting Lake has great changes, Dongting Lake dominant species of fish in descending order according to the dominance is carps, Crucian Carp, Catfish, Yellow Catfish, et al. The survey found no diadromous fish, migratory fish species in rivers and lakes is also less than before, migratory fish reduced by38.8%, with great spatial and temporal variations.3. The diversity indices were calculated. The results showed that fish diversity of the lake was high. Shannon-wiener biodiversity index of March2012and July2012were higher while November2012was lower, with great seasonal variations. The main reason for these differences is mainly the sake of fishing and seasonal variations. From the spatial extent of the Dongting Lake, the highest diversity index in East Dongting Lake, the Chenglingji and the South Dongting Lake followed, the West Dongting Lake the lowest.4. Determination main economic fish:carps, Crucian Carp, Catfish and Yellow Catfish, it showed that, Dongting Lake Species dominant group are concentrated in the lower group of body length and weight group, the small individuals are dominant, from their body length and weight distributions.5. In order to make better use of fish and aquatic biological resources and protect aquatic ecological environment of Dongting Lake, we need to establish a sustainable development and legal concepts, improve the ecological environment as well as to further improve the fishery management system, to achieve fisheries the goal of sustainable development in Dongting Lake. |
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