台湾海峡中北部海域刺鲳种群生态学参数及其变动趋势

以2001～2002年周年逐月采集台湾海峡中北部单拖渔船渔获的刺鲳样品578尾,进行群体结构和生长与死亡关系的研究,与1982～1984年渔获群体结构进行了比较,并结合1995～2008年渔业投入量和产出量的变化,探讨其种群变化趋势及管理策略.结果表明：2001～2002年刺鲳群体的L∞值为238.17 mm,W∞值为506.31 g,k值为0.338 3,t0值为-0.953 4a,tr值为2.146 2a.总死亡系数为2.364 1,自然死亡系数为0.841 5,捕捞死亡系数为1.523 0.与1982～1984年相比,渔获群体发生了个体小型化、结构低龄化、性成熟提早等生态学变化.这些变化与该渔场自1993年以来不断加大捕捞的投入和渔获量的产出且大量捕杀幼鱼,开发比率高达0.644 1,处于过度开发有关.因此必须强化对渔业资源的管理,同时实施最小可捕叉长为126.19 mm和最小可捕体重为58.81 g的管理制度,使该海域渔业资源得以恢复,实现渔业的可持续发展.

Changes in ecological parameters and resources of Japanese butterfish,Psenopsis anomala, in the middle and northern Taiwan Strait

Biological data were recorded for 578 individuals of Psenopsis anomala collected using a single boat trawl in the middle and northern Taiwan Strait between 2001 and 2002.The population structure,growth parameters and mortality were studied and compared with previous studies from 1982 and 1984 and the total fisheries capture from 1995 to 2008.Trends in the population structure of P.anomala and possible management steps are discussed.The growth parameters of P.anomala were： L∞=238.17 mm,W∞=506.31 g,k=0.338 3,t0=-0.953 4a（t0 is the age when the theoretical fork length is 0）,tr=2.146 2a（tr is the age of the inflexion point of body weight growth）,the rates of total mortality,natural mortality and fishing mortality were found to be 2.364 1,0.841 5 and 1.523 0,respectively,and the exploitation rate was 0.644 1.When compared with the population structure of stocks from 1982 and 1984 it was evident that current adults mature early and have fast growth and are thus smaller and younger than in previous years.These changes may be caused by enhanced input-output of fishing in this area and overfishing with heavy exploitation of juvenile P.anomala（with an exploitation rate as high as 0.644 1） since 1993.Therefore,it is suggested that the minimum capture fork length and body weight were should be 126.19 mm and 58.81 g,respectively and at the same time protection and management of fish resources should be intensified to restore this fishery and achieve sustainability.