东海北部哈氏仿对虾的种群动态及其最高持续渔获量

Population dynamics and estimation of maximum sustaining yield for Parapenaeopsis hardwickii in the northern area of East China Sea

哈氏仿对虾是东海北部主要的拖虾渔业对象。在雌性的体长组成中 ,70～ 90mm的个体占优势 ,占总数的6 3%。应用ELEFANⅠ和ELEFANⅡ技术对哈氏仿对虾每月的体长资料进行分析 ,结果表明 :生长参数K =1.7,极限体长L∞ =12 8mm ,自然死亡系数M =2 .742 7,总死亡系数Z =8.32 3 ,利用率E =6 7.0 6 % ,极限年龄为 1.32 34岁 ,选择体长为 5 9.6 7mm ,补充类型为二季补充型。通过单位补充量产量Y/R和单位补充量产值Yv/R分析表明 ,该群体的利用已到了相当充分的水平 ,若保持现有的捕捞水平 ,把开捕体长增大至 70mm时 ,单位补充量产量可增加 1.77% ,产值可增加 10 .78%。但若捕捞死亡水平继续增加 ,产量几乎不再增加 ,而产值却明显下降。

Based on the monthly length frequency data obtained from the northern area of East China Sea during the periods of 1986-1987 and 1993-1995, the population dynamics and maximum sustaining yield of Parapenaeopsis hardwickii were studied. The dominant length group for the female was 70-90mm, which was 63% of the total female. By using ELEFANⅠ and Ⅱtechnique, the growth parameters were estimated: K=1.7, L ∞=128mm and t 0=-0.1185, the approximate longevity was 1.3234 years. Total mortality z=8.3280 ,and mean selection length L c=59.67mm.Natural mortality M=2.7427 was estimated by using the empirical relationship between M, the growth parameters and mean environmental temperature,and the exploitation rate, E=F/Z=0.6706,was obtained. Yield per recruit and the value of yield per recruit analysis indicated that the stock of Parapenaeopsis hardwickii had been fully exploited. An increase in yield per recruit and the value of yield per recruit may be expected if the size of first capture has a moderate increase. The value of yield per recruit would be reduced with the increase of fishing mortality.