捕捞和环境变化对渤海生态系统的影响

Effects of fishing and environmental change on the ecosystem of the Bohai Sea

以1982年的渤海Ecopath静态模型为起始状态,设置17个功能群,利用CPUE和渔业相对捕捞强度作为时间强制序列,构建渤海Ecosim模型,模拟1982—2008年渤海生态系统发育的动态变化及捕捞的影响;利用气候环境时间序列数据,分析环境变化对渤海生态系统渔业资源的影响。研究发现,1982—2008年间,只有口虾蛄的生物量保持上升趋势,主要经济鱼种小黄鱼、蓝点马鲛、鳀、花鲈、黄鲫等的生物量均呈下降趋势,虾蟹类、头足类的生物量相对稳定。渤海渔获物的平均营养级在1982—2008年间明显下降,总捕捞产量在1984年之后一直保持上升趋势,两者之间存在显著的负相关;FIB指数的变动与捕捞产量的变动保持一致。Q-90多样性指数在1982—1987年间处于波动状态,从1988—1994年间保持增长趋势,在1994年之后迅速下降,由2.5降至0.5附近,渔业生物多样性下降;渤海海表盐度、海表水温、黄河径流量对捕捞产量影响显著。Ecosim模型终止状态(2008年)与起始状态(1982年)的比较表明,系统成熟度降低,生态系统出现一定程度的退化,渔业捕捞是渔业生态系统出现退化的主要原因,降低了生态系统总体的生物量水平;除捕捞因素外,环境变化也是影响渤海生态系统渔业资源变动的主要因素。

Using a 1982 model of the Bohai Sea as the starting state, an Ecosim model was constructed for the Bohai Sea, including the 17 functional groups. Using time series of catch per unit effort （CPUE） and relative fish- ing effort as the driving factors, this model simulated the dynamic changes in different developmental stages of the Bohai Sea ecosystem and the impact of fishing on this ecosystem. The effects of climate change on the fishery resources of the Bohai Sea ecosystem were analyzed based on the environmental time series data. From 1982 to 2008, the biomass of Oratosquilla oratoria showed an increasing trend, and the biomasses of some species of high economic value showed decreasing trends, including Pseudosciaena polyactis, Scomberomorus niphonius, En- graulisjaponicus, Lateolabraxjaponicus, and Setipinna taty, and the biomasses of shrimp, crabs, and cephalopods were relatively stable. The mean trophic level of the catch clearly decreased from 1982 to 2008, and correlated significantly negatively with the total catch. The fishing-in-balance （FIB） index followed the same trends as the total catch, increasing after 1984. The Q-90 diversity index fluctuated slightly from 1982 to 1987, maintaining a growth trend in 1988-1994, followed by a rapid decline after 1994, from 2.5 to around 0.5, and the fishing biodi- versity decreased. The surface salinity, surface temperature, and Yellow River runoff significantly affected the fishing yield in the Bohai Sea. A comparison of the initial （1982） and end states （2008） of the model showed that the maturity of the ecosystem decreased. Overfishing resulted in the degeneration of the ecosystem and a decline in the total biomass. Thus, fishing and environmental changes were the main factors affecting the changes in the fishery resources in the Bohai Sea ecosystem.