Biodiversity Status Of Fishery Community In Lower Reaches Of Yangtze River And Primary Evaluation Of The Spring Closed Effect

Studies on biodiversity status of fishery community in lower reaches of Yangtze River were carried out,and primary evaluations of the Spring Closed effect on fishery community in the sections of Chongming,Changshu and Anqing were also done.During 2004-2005,studies on fishery community in lower reaches of Yangtze River were carried out and a better understanding on its characteristics description and fishery yield calculation were reached.Besides that,comparisons of relative indexes among all the sampling stations were attained at the same time.In the community fishes of 14 oders,32 families,66 genera and in all 82 species,most of which were settled in fresh water,were occupied.Among them the one with its unit weight under 100g were more than others and the dominant species were Parabramis pekinensis,Carassius auratus and Coilia mystus. Indexes of biodiversity could be summarized as Margalef's index 6.46,Shannon-Wiener's 2.41,Simpson's 0.14 and Pielou's 0.55.Average yield per boat accounted for 5519.2kg.Studies on fishery community in Chongming section in the Spring Closed season during 1999-2005 were carried out,and contrast analysis of correlative indexes before and after the Spring Closed was also done.During the period,fishes,shrimps and crabs,which belong to 12 orders,22 families,33 genera and 37 species were collected.The dominant species were Coilia mystus,Collichthys lucidus and Stromateoides argenteus after the Spring Closed, while small species with its unit weight under 20g were remarkably more than others.Average index of biodiversity characters after the Spring Closed indicated that Margalef's index 1.50,Wilhm's 1.83,Simpson's 0.24 and Pielou's 0.72.Studies on fishery community in Changshu section in the Spring Closed season during 2000-2005 were carried out,and contrast analysis of correlative indexes before and after the Spring Closed was also done.In the period,fishes,shrimps and crabs,which belong to 11 orders,17 families,33 genera and 38 species were collected.The dominant species were Parabramis pekinensis,Pelteobaggrus fulvidraco and Mugil cephalus after the Spring Closed,and species that was more than 100g of its unit weight were remarkably more than others.Average index of biodiversity characters after the Spring Closed indicated that Margalef's index 3.32,Wilhm's 2.50,Simpson's 0.18 and Pielou's 0.76.Studies on fishery community in Anqing section in the Spring Closed season during 1999-2005 were carried out,and contrast analysis of correlative indexes before and after the Spring Closed was also done.In the period,fishes,shrimps and crabs,which belong to 8 orders,14 families,38 genera and 45 species were collected.The dominant species were Cyprinus carpio,Parasilurus asotus and Cyprinus carpio after the Spring Closed,and the species that was more than 100g of its unit weight were remarkably more than others. Average index of biodiversity characters after the Spring Closed indicated that Margalef's index 3.28,Wilhm's 2.45,Simpson's 0.16 and Pielou's 0.79.In all the results showed that in Chongming section the Spring Closed brought evident change to the community composition while the complexity got certain drop.Meanwhile Characters of biodiversity fluctuated in a wide range,and it indicated little uptrend sign towards stability.On the contrary notable advance of both fishery community complexity and biodiversity level in the sections of Changshu and Anqing could be found.