渤海鱼类群落结构及其动态变化

The structure and variation of fish community in the Bohai Sea

渤海鱼类群落由１１５个种组成，暖温性种占５４．８％。生物量超过万ｔ的只有鱼１种，千ｔ以上的有黄鲫、斑、小黄鱼、赤鼻、孔鳐、棘头梅童、鲈鱼７种，其它种生物量都不足１０００ｔ。群落结构以浮游动物食性的种为主，占总生物量的７４．２％。繁殖力以１万～１０万粒的力种为主，占６７．６％。体长结构主要是体长小于１００ｍｍ，体重小于２０ｇ的小型个体，占７５．７％。从１９８２年～１９８３年到１９９２年～９９３年，渤海鱼类群落发生了较大变化，种类减少，种的均衡性变差，Ｓｈａｎｏｎ－ｗｉｅｎｅｒ指数由３．６０９２降到２．５２９６，生物量在１０００ｔ以上的高生物量种由１３种减少到８种，浮游动物食性鱼类的生物量占总生物量的比例由５９．９％上升到７４．９％，游泳动物食性的比例则由９．５％降到１．６％，怀卵量在１万～１０万粒的高繁殖力种由５３．２％上升到７２．９％，体长１００ｍｍ，体重２０ｇ左右的小个体所占比例则由５８．６％上升到７５．７％。

The fish community of the Bohai Sea is composed of 115 species, of which the warm-temperate species account for 54.8%.The biomass of Engraulis japonicus is over 10000t,and that of other seven species is over 1000t including Setipinna taty, Clupanodon punctatus, Pseudosciaena polyatis,Thrissa kammalensis, Raja porosa, Collichthys lucidus,and Lateolabrax japonicus.The biomass of the rest is less than 1000 t. The Community structures are dominated by species preying on zooplanktophagous,which account for 74.2% of the total biomass. The species with high fecundity (104～105 eggs)account for 67.6%. The small sized species with less than 10 cm in body length and 20 g in body weight account for 75.7%. The fish community of the Bohai Sea has largely changed from 1982～1983 to 1992～1993, indicating that the number and evenness of species have reduced, with the Shannon-wiener index from 3.6092 down to 2.5296, the number of species with high biomass (over 1000 t ) from 13 down to 8, the percentage of zooplanktonphagous fish in total biomass from 59.9% up to 74.9%, nekton feeders from 9.5% down to 1.6%, species with high fecundity from 53.2% up to 72.9%, the small sized species from 58.6% up to 75.7%.