摘要
本文利用渔捞统计、年龄组成等生物学资料,探讨了东海群带鱼的增殖关系,得出东海群带鱼的增殖曲线为 R=1525Ae^(-0.0016A) 。最大补充量时所需的亲鱼量 A_M=600。并将从增殖曲线公式求得的增殖关系理论值,用亲鱼与补充量关系模式进行了模拟计算。求得了最初被捕年龄t_0=1～5时的资源持续产量和最大持续产量。计算结果表明: (1)t_c=1时,原始资源水准时的亲鱼量 A_V=4659,平均体重W=414.9克,捕捞对象资源量(尾数)N_V=9.9×10~3。虽然鱼体大,平均体重大,但由于资源增殖率低,资源量水准也低。 (2)最大持续产量时亲鱼量A=600,只有原始资源水准时的1/8,平均体重只有原始资源水准时的1/4。但由于补充量为最大,捕捞对象资源量(尾数)却增加了近35倍,资源量(重量)亦增加9倍。 (3)目前由于捕捞强度不断增大,产量超过了资源最大持续产量,1978年亲鱼量已下降到A=154,只有最大持续产量时的1/4,这是资源利用过度的危险水平。捕捞对象资源量和补充量都只有最大持续产量时的1/2多一点。 (4)要使资源恢复到最大持续产量水准,必须采取限制产量的措施。将产量控制在低于持续产量水平,使剩余的亲鱼量能逐步恢复到A=600水平。如果1979年将产量控制在1978年产量的80%水平,到1980年亲鱼量或可恢复到A=600水平。这样再过两年。
Recently, reproductive mechanism have been widely used in studying fish popula-tion dynamics. In this report, the reproduction curve is plotted by the formula R = 1525Acon the hairtails in the Dong Hai, although numbers, parent and offspring, describedhere are in relative index instead of absolute number. The theorctical value of theraproductive relation obtained from the formula of the reproduction curve is treated bythe mathematical model in stationary state from the known parameter of hairtails men-tioned above. The results obtained by solving the mathematical model indicate that: (1) According to various values of age at first capture te, sustainable yield curvescan be plotted. At the maximum sustainable yield the number of parents A= 600 lies on1/8 of virgin stock level, and the age of first capture is t_c = 1 - 5. (2) In considering the maximum sustainable yield in weight, age at first capture isdesirable to be 3, instead of 1, 2, 4 and 5. (3) If the present status of stock level has been reduced to 1/4 of stock level, onwhich the maximum sustainable yield was provided, it is the signal of overfishing. (4) For the purpose of recovery of this hairtails population, regulation measuresshould be cousidered. The yield must be limited under the level of the sustainable yield.If 20% should be reduced, for 1--2 years and if number of parents gradually reach toA -- 600, then the yield would be recovered to the optinum level of the maximum sustain-able yield.
出处
《水产学报》
CAS
1980年第1期47-61,共15页
Journal of Fisheries of China
