北部湾底层渔业资源的数量变动和种类更替

DYNAMICS AND SUCCESSION OF DEMERSAL RESOURCES IN BEIBU GULF

根据渔业统计资料和底层渔业资源调查数据，分析了北部湾底层渔业资源的数量变动和种类更替。（１）北部湾底层渔业资源的密度指数有明显的季节变化，这一变化主要是本海域主要底层种类生长、死亡和补充共同作用的结果；（２）主要经济种类的组成随捕捞压力的增加而变化，其种类更替的趋向是质量差、寿命短、个体小和营养层次低的种类的比例上升，质量高、寿命长、个体大和营养层次高的种类的比例下降；（３）多鱼种渔业资源的潜在渔获量随着增加捕捞压力所引起的种类更替而上升。目前北部湾渔业资源的潜在渔获量为６０—６５万吨。

This study analyses dynamics and succession of the demersal resources in theBeibu Gulf according to fishery statistics and data on bottom stock surveys.The results are asfollows:(1)There are distinct seasonal variations in density index of bottom stock. In general,thevariations result from recruit ,growth and death of main species。(2)The composition of Main commercial species obviously changes with the increasing offishing pressure。 The succession tends to an increase in species of lower quality,shorter life span,smaller individual and lower trophic levels and,to a decrease in species of higher quality,longer life span ,larger individual and higher trophic levels。(3)Potential yield of multispecies fishery stock increases with the succession that resultsfrom increasing fishing pressure. At present,the potential yield in Beibu Gulf is estimated at600000 650000tons.