渤海鱼类群落结构及其主要增殖放流鱼类的资源量变化

基于2010年5月和8月渤海渔业调查数据,结合1959年以来渤海鱼类相关文献资料,对渤海鱼类群落结构的演替、主要增殖放流鱼类的资源动态作了初步分析.结果表明,渤海鱼类群落优势种由个体大、营养层次高的带鱼Trichiurus haumela、半滑舌鳎Cynoglossus semilaevis等优质底层鱼类逐渐被黄鲫Setipinna taty、鳀Engra ulis ja ponicus等个体小、营养层次低的小型中上层鱼类所替代,并且除黄鲫外,其他小型鱼类优势种也在不断更替中.另外,生物健康度指数(BHI)分析显示,渤海鱼类群落处于相对不稳定状态.鱼类资源量急剧降低,尤其在5月,CPUE由1959年的186 kg/h下降至目前不足1 kg/h,鱼类资源密集区主要分布在莱州湾、渤海湾和渤海中部,而辽东湾分布相对较少,并且鱼类资源与海蜇呈交错分布.近年来,渤海增殖放流的鱼类仅有花鲈Lateolabrax japonicus和许氏平鲉Sebastes schlegeli的资源量有小幅度回升,其他种类从20世纪80年代开始资源量一直处于下降趋势.从渤海鱼类群落结构的演替和增殖放流鱼类的资源量变化来看,渤海鱼类群落依旧是小型经济价值较低的种类控制其能流结构.除花鲈外,其他增殖放流鱼类的资源量均不足历史最高资源量的1％,其资源量的恢复尚有很大的空间,增殖潜力很大.

Fish community structure and stock dynamics of main releasing fish species in the Bohai Sea

Based on the bottom trawl data in May and August, 2010 in the Bohai Sea, combined with the fishery data and literature in the Bohai Sea since 1959, the succession of fish community structure and the stock dynamics of main releasing fish species in the Bohai Sea were analyzed. The shift of dominant species was rapid, and large sized, high trophic level species (e.g. Trichiurus haumela, Cynoglossus semilaevis and so on) were replaced by small sized and low trophic level species (Setipinna taty, Engraulis japonicus and so on). Rapid shifts in small sized fish species were also found in fish community in recent years, excluding Setipinna taty, which was the dominant species in fish community since the 1980s. In addition, fish community structure was in a fluctuating state versus time according to the analysis of biology healthy index. Fish catch per unit effort in May sharply decreased from 186 kg/h in 1959 to no more than 1 kg/h in the present. Fish stock mainly distributed in the Laizhou Bay, Bohai Bay, and the central part of the Bohai Sea,but much less in the Liaodong Bay, and staggered biomass distribution were found between fish and jellyfish. The biomass of releasing fish species Lateolabrax japonicas and Sebastes schlegeli increased slightly in recent surveys, but that of other releasing fish species showed a decreasing trend since the 1980s. The biomass of a few releasing fish species was restored to some extent by stock enhancement, yet still less than 1% of the maximum biomass in history (excluding L. japonicas). Fish community in the Bohai Sea was dominated by small sized and low trophic level species, indicating that a lot of work needs to be done for stock enhancement.