基于长时间序列的中东大西洋渔获物平均营养级及资源状况变化分析

Analysis of mean trophic level of catch and exploitation of fishery resources in the Eastern Central Atlantic based on long time series

为了解中东大西洋渔业产区渔获物的资源状况,根据世界粮农组织(FAO)提供的该海域1950—2019年的渔获量数据,结合渔获种类的平均营养级(mean trophic level,MTL)信息,运用统计学方法分析70年间渔获物平均营养级和营养级平衡指数(fishing in balance,FiB)的变动规律,以掌握该海域渔业资源的可持续利用情况。结果显示,MTL大致可分为4个阶段,1950—1956年,MTL指数在3.20左右,无明显变化;1957—1963年,MTL指数迅速上升至3.44;1964—1996年,MTL在波动中趋于下降,历史最高值(3.54)出现在1985年;1997—2019年,MTL稳定在较高水平,其中2018年为该阶段最低点3.35。FiB指数整体呈上升趋势,1950—1956年,FiB指数呈小幅波动增加;1957—1974年,FiB指数显著上升;1975—1996年,FiB指数呈平稳波动状态;1997—2019年,FiB指数整体呈小幅增长趋势。结果表明,中东大西洋海洋生态系统相对稳定,但潜在的渔业资源量越来越少,开发潜力有限。

The Eastern Central Atlantic Ocean is an important fishery area in the world.The evaluation of fishery resource development is helpful to formulating reasonable management and preventive measures to achieve sustainable development.To understand the fishery resources in the Eastern Central Atlantic Ocean,Food and Agriculture Organization(FAO)provides fish catch data for the period 1950—2019,combined with mean trophic level(MTL)information of fish species,in order to master the sustainable utilization of fishery resources in this fishing area,the average trophic level and trophic level balance index(FiB)of fish catch during 1950—2019 were analyzed by statistical methods.The results show that the catch of this area has fluctuated and increased in the past 70 years,from 30×10^(4) t in 1950 to 546×10^(4) t in 2018,the highest level in history.A total of 418 species were caught in this fishing area.Countries and regions with more species were mainly from Europe and coastal countries of West Africa.Spain caught the most species 180,led by Thunnus obesus and Merluccius senegalensis.More than 100 species were also caught in Portugal(121 species)and Liberia(106 species).The main catch species were Thunnus obesus and Galeoides decadactylus.The top five species in terms of cumulative catch from 1950 to 2019 were Sardina pilchardus,Sardinella aurita,Scomber colias and Ethmalosa fimbriat and Katsuwonus pelamis,whose cumulative catches were more than 660×10^(4) t,accounting for 36.5%of the total catch.MTL could be roughly divided into four stages.From 1950 to 1956,MTL index was low without significant change.From 1957 to 1963,MTL index rose to 3.44.From 1964 to 1996,MTL tended to decline in fluctuation,and the highest value(3.54)appeared in 1985.From 1997 to 2019,MTL stabilized at a high level,and reached the lowest of 3.35 in 2018.The FiB index showed an upward trend,and the FiB index increased slightly from 1950 to 1956.From 1957 to 1974,FiB index increased significantly.From 1975 to 1996,FiB index was relatively stable without big fluctuation.From 1997 to 2019,FiB index showed a steady growth trend.The results indicated that the mean trophic level of catch decreased with the increase of catch,while the FiB index did not decrease,indicating that the increase of catch made up for the decrease of MTL,and FDFW phenomenon did not appear.The marine ecosystem in the Eastern Central Atlantic Ocean is relatively stable,but the amount of potential fishery resources is getting smaller and smaller,and the development potential is limited.