长江天鹅州故道鱼类群落种类多样性

Species diversity of fish community in Swan Oxbow of Changjiang River

１９９３年２月至１９９４年１月，在长江开敞型的天鹅洲故道采集鱼类４９种，分属５目１３科，其鱼类群落由湖泊型鱼类和江河型鱼类组成。Ｓｈａｎｎｏｎ指数、Ｗｉｌｈｍ改进指数和Ｓｉｍｐｓｏｎ指数分别为３．７０、４．１９和０．８９；均度为０．６６。年总渔获量为３７４５３０．８ｋｇ，其中青鱼、草鱼、鲢及鳙共占１７．９７％。由于捕捞过度，天鹅洲故道鱼类群落表现为强烈的小型化、低值化趋势，年总渔获量的６６．１８％为小型、低值鱼类。

From Febuary,1993 to January,1994,fishes of 5 orders,13 families and 49 species were collected from the Swan Oxbow of Changjiang River where the fish community consisted of riverine and lacustrine types. The Shannon index(H′),Wilhm index,(H″) and Simpson index (D) in Swan Oxbow were 3.70,4.19 and 0.89,respectively. The eveness (E) was 0.66. The annual fish yield was 374530.8 kg in 1993, of which the black carp, grass carp, silver carp and bighead carp account for 17.97% . In Swan Oxbow, overfishing is a major problem, which causes small-sized and low-valued trend of fish community. Small-sized and low-value fish made up 66.18% of the annual yield. 