广西龟石水库大眼鳜的年龄与生长特征

2008年9月2009年8月,在广西龟石水库用刺网逐月采集大眼鳜(Siniperca kneri)标本688尾,摘取鳞片作为年龄鉴定的主要材料,摘取鳃盖骨和臀鳍第二鳍棘作为年龄鉴定的辅助材料,研究大眼鳜的年龄特征,并采用von Bertalanffy生长方程描述了大眼鳜的生长特性,为合理利用和保护库区大眼鳜资源提供科学依据和理论参考。结果表明,以鳞片作为大眼鳜年龄的鉴定材料较可靠,年轮特征显示为疏密型和断裂切割型,年轮主要形成时期在4 6月,年轮的形成与繁殖有关;年龄组成为0~4龄,0龄和1龄鱼占标本总数的93.32%;体长(L)与鳞径(R)的回归方程为:L=24.47R+4.021 2(r=0.981 9,n=623);体长(L)与体质量(W)的回归方程为:W=0.017 7×L3.087 6(r=0.979 1,n=688);体长、体质量的von Bertalanffy生长方程为:Lt=59.04l-e-0.2692(t+0.251 9)],Wt=5 196.88l-e-0.269 1(t+0.263 8)]3.087 6。分析龟石水库大眼鳜资源现状,认为渔获物中低龄个体占绝对优势与库区无节制捕捞有关。为保护与合理利用库区大眼鳜资源,建议将库区大眼鳜的最小捕捞年龄定为3龄,捕捞规格定为990 g以上。

Age and growth of bigeye mandarinfish (Siniperca kneri) in Guishi Reservoir, Guangxi Province

We evaluated the age and growth of bigeye mandarinfish(Siniperca kneri) in the Guishi reservoir Guangxi Province using scales,opercula,and anal-fin spines.We collected 688 specimens between September 2008 to August 2009.The interpretation of age based on scale readings was reliable.Annual rings were formed primarily by the pattern of sparseness-denseness and the cut of the scales.The pattern of sparseness-denseness was visible in the prezone region whereas the cut pattern was present on the rear-side region.Annuli formation took place primarily between April and June each year,likely related to the timing of reproduction.The estimated ages ranged between 0 and 4 years old,but were dominated by the younger age classes(age 0 and 1).The body-length of specimens ranged from 11.25 to 40.50 cm,with the majority(70.49%) being 15–21 cm.Body weight ranged from 29.1 to 2 257.8 g,but most fish(62.12%) were between 100–300 g.The body length-scale radius relation-ship was L=24.47R+4.021 2(r=0.981 9,n=623).The body length-weight relationship was W=0.017 7×L3.087 6(r=0.979 1,n=688).The b value was close to 3,therefore,S.kneri was considered to be isometric.The growth equations for body length and weight were Lt=59.04l-e-0.269 2(t+0.251 9)] and Wt=5 196.88l-e-0.269 1(t+0.263 8)]3.087 6,respectively.The inflexion age on the growth rate curve for weight was 3.93,and corresponded to a body-length of 39.89 cm and weight of 1 554.81g.Our data suggest that the bigeye mandarinfish population had been overex-ploited.To protect the population and allow for sustainable utilization,we suggest only fish greater than 990 g(age 3) should be harvested.