长江河口区凤鲚的资源现状

STATUS QUO OF TAPERTAIL ANCHOVY RESOURCE IN THE ESTUARIES OF THE YANGTZE RIVER

对近年来长江河口区凤鲚繁殖生物学及资源现状进行了研究。研究结果表明 :繁殖期渔获物平均全长 1 6.1 4± 1 .70cm ,平均体重 1 3.93± 4.2 1g。全长与体重呈幂函数相关 ,W =0 .0 0 34L2 .8891 ,R2 =0 .90 34。成熟卵卵径 0 .67± 0 .0 8mm ,绝对怀卵量 1 41 90± 470 3粒 ,相对怀卵量 1 0 73± 1 75粒 /g体重。繁殖期个体绝对怀卵量与全长、体长均呈直线相关。 1 997— 1 999年长江河口区凤鲚总渔获量在 1 1 64t左右 ,不随捕捞努力量的增加而增加 ,汛末瞬时资源量维持在 2 0— 30t,与历史年份相比较 ,捕捞产量下降明显。其原因是 :捕捞强度过高、水域环境恶化。

The studies on reproductive biology and resource present of tapertail anchovy in the estuaries of Yangtze River in the recent years were carried on.The result showed that the average total length and body weight of the catching during the spawning period were 16.14±1.70cm and 13.93±4.21g,respectively.The total length was related to the power function of the body weight:W= 0.0034L 2.8891 ,R 2=0.9034.The diameter of matured egg was 0.67±0.08mm;the absolute fecundity was 14190±4703 eggs/fish,and the relative fecundity was 1073±175 eggs/g body weight.The absolute fecundity of the fish in spawning season had liner relationship with the total length and body weight. The total catching of tapertail anchovy in the estuaries of the Yangtze River varied around 1164 tons during 1997-1999,and the catching did not increase with the fishing effort.The abundance of the fish maintained between 20 and 30 tons at the end of the fishing season.Compared with previous years,the total catching declined significantly.The authors held that over fishing,deterioration of water environment and damage to the natural spawning ground were the main reasons,which caused the resources of tapertail anchovy to decline.