南海北部多齿蛇鲻生物学分析

Biology analysis of Saurida tumbil in northern South China Sea

综合20世纪60～90年代南海北部多齿蛇鲻(Sauridatumbil)的生物学资料,利用ELEFAN技术计算生长参数,得到的VonBertalanffy生长方程的相关参数为:L∞=58.5cm,K=0.30,t0=-0.39。根据生长参数及鱼类栖息环境平均水温用Pauly公式计算得自然死亡系数为0.61。根据各个年代的资料采用长度变换曲线法计算总死亡系数,进一步计算捕捞死亡系数,20世纪80年代捕捞死亡系数为1.55,是20世纪60年代的近2倍,20世纪90年代捕捞死亡系数与80年代相比又增加了1倍,在目前的开捕规格下,渔业点进一步偏离了最适产量区;若维持当前的开捕规格及捕捞强度不变,会导致多齿蛇鲻资源的进一步衰竭,而且也不符合经济效益的要求。综合考虑多齿蛇鲻的性成熟特征、当前可能的捕捞强度及经济效益,在有利于恢复资源又能保持相当产量的前提下,建议尽可能的降低捕捞强度的同时对南海北部多齿蛇鲻的开捕体长由13.5cm增加至22.0cm。

Saurida tumbil (Bloch et Schenider) belongs to Myctophiformes, Synodidae, mainly distributed in the India Ocean, the west Pacific and the Yellow Sea and south China Sea. In South China Sea the highest production once reached 18 000 t. Since 1960s', this species has been one of the main captured fish in South China Sea. Some reports on its resource and morphology have been published. But different analysis method and shortage on basic investigating data made some results have errors and subjectivity. In this experiment, growth parameters of Saurida tumbil in northern South China Sea were estimated using ELEFAN technology and the biology data collected from 1960s to 1990s. The results showed that the growth parameters of Von Bertalanffy growth equation was L_∞=58.5 cm,K=0.30,t_0 =-0.39; Natural Mortality Coefficient (M ) was (0.61) from Pauly equation according to growth parameters and average water temperature; Total Mortality Coefficient (Z ) was got from length-converted catch curve with biology datum in different era. The Fishing Mortality Coefficient (F ) in 1980s was calculated that F equaled to 1.55, which increased twice times compared with that in 1960s, and F in 1990s increased twice times compared with that in 1980s, indicating the yield spots nowadays have been in outsides of the optimum yield region. According to the isogram of catch, the stock resource of Saurida tumbil can't be exploited until the body length at first capture (L_ c)reaches to 13.5 cm and F to 3.65. Taking into account the character of sex mature, possible fishing effort and economic requirement, it's suggested that L _c should be decreased from 22.0 cm to 13.5 cm and great efforts in reducing fishing intensity should be made by the government.