2007年1-12月在北部湾口采集477尾深水金线鱼标本,使用FiSATⅡ软件中的ELEFANI程序包对其生长参数进行了估算。一维方差分析结果表明,北部湾口海域深水金线鱼体长和体质量相关性无显著性性别差异(P〉0.05),雌、雄混合后的体长和体质量关系方程为mt=5.4604×10^-5Lt^2.875;VonBertalanffy生长方程为Lt=244.7×{1-exp[-0.42×(t+0.37)]},mt=402.3×{1-exp[-0.42×(f+0.37)]}^2.875;体质量生长拐点2.3龄,对应体长163.1mm;逻辑斯蒂方程求解的50%性成熟体长为121.5mm;体长组成资料的累计渔获量曲线估算的总死亡系数为2.28,Pauly经验公式计算自然死亡系数为0.49,北部湾口海域2007年深水金线鱼的开发率达到0.79,资源处于过度开发状态。Beverton & Holt模型研究表明,当前北部湾口海域深水金线鱼的开捕年龄偏小。建议在当前捕捞力量下,增大tc至2龄,此时深水金线鱼体长为152.3mm,单位补充量渔获量可达到68.5g/尾。
The growth and mortality parameters were estimated in 477 specimens of bottom threadfin bream Nemipterus bathybius collected from Donggang Port of Sanya city in the Mouth of Beibu Gulf, South China Sea, in 2007 by ELEFAN Ⅰ program package. The relationships between body length and body weight were expressed as power functions. One-Way ANOVA of the difference of the relationships between genders showed that there were no significant differences (P〉0.05), therefore, the equation of body length and weight for all specimens was expressed as mt=5. 4604 × 10^-5 L1^2.875 , in which rn, was the body weight (g) and L, was body length (ram). The length-at-age and weight-at-age data of the fish were fitted to the Von Bertalanffy growth function. Equations obtained from ELEFAN I in FiSAT 11 package were Lt=244.7{1-exp [(-0.42(t+0.37)]} and m,=402.3{1--exp[(--0.42(t+0.37)]}^2.875, in which t and L, were age of (year) and the body length (ram) at age t. The fish at 50% maturity had body length of 121.5 mm calculated by logistic model. An inflectional point, where the acceleration of the body weight growth reached maximum, was found at age of 2.3 years, and body length on that point was 163.1 mm. Total mortality coefficient (Z) of the stock estimated by Jones and Van Zalinge method wa.s found to be 2.28. The natural mortality (M) calculated by Pauly's empirical was 0.47. The exploitation rate of the fish reached 0.79 (overexploited) in the Mouth of Beibu Gulf. Beverton & Holt model indicated that the catchable body length was smaller, base on this study, it is suggested that the catchable age augue to 2 years old, with body length of 152.3 mm, and yield per recruitment of 68.5 g/individual, leading to the best harvest and sustainable development of the fish in the Mouth of Beibu Gulf.