Analysis on responses of hairtail catches to fishing and climate factors in the Yellow Sea and Bohai Sea, China

Abstract

Changes in fish harvest are not only impacted by fishing,but also influenced by climate variability.Based on data of hairtail catches between 1956 and 2006 in the Yellow Sea and Bohai Sea,China,the responses of catches to fishing and climate factors were analyzed.The catch time series can be compartmentalized into an in-ter-annual trend and variations.The inter-annual trend was mainly attributed to growth in fishing efforts.This was suggested by highly significant regression of hairtail catches to fishing effort fitted by the Fox model(P0.01).After the catch trend was removed,there were positive partial correlations(P0.02) of the residual variations in catches to winter wind speed in the Yellow Sea,summer wind speed in the East China Sea,and annual precipita-tion in Yellow River Valley and the coastal region of the Yellow Sea and Bohai Sea,whereas the partial correla-tions to sea surface temperature and summer wind speed in the Yellow Sea,as well as summer and winter wind speeds in the Bohai Sea were negative(P0.05).The linkage suggests that the climate factors govern the hairtail catch variations.It was inferred that runoff input nutrients to the Yellow Sea and Bohai Sea,while monsoons con-trolled the transport and distribution of the nutrients,and these processes can have impacts on the primary produc-tivity.Changes in water temperature could also directly affect the growth,feeding,spawning,and migration of the fish,and thus,influence the fish population size.The hairtail catch time series can be jointly fitted by fishing ef-fort and climatic factors(P0.01),suggesting that,in addition to fishing,climate factors can significantly influ-ence the hairtail catches.In the context of global warming,it was projected that the future climate changes would lead to reduction in hairtail production in the Yellow Sea and Bohai Sea,and the hairtail catch variations would become even greater.