武汉东湖鲢、鳙生长的几个问题的研究

采用退算法研究东湖鲢、鳙的生长,包括生长的基本模式,瞬时生长率及其变动,雌、雄鱼生长的差异等问题:1)鲢、鳙的生长模式可用von Bertalanffy方程来描述,其中鲢的参数l∞=99.8厘米、W∞=17,104克、K=0.3040、t0=0.4821年,鳙的参数l∞=117.6厘米、W∞=29,311克、K=0.3088、t0=0.5392年;2)鲢、鳙的瞬时生长率随着年龄的增长而逐渐下降,并且不同世代同龄鱼的瞬时生长率有一定的变动,其变差系数与年龄呈正相关;3)鲢、鳙的生长无显著的性别差异。通过对研究结果的综合分析,阐述了鲢、鳙4龄前后出现生长的拐折主要由其个体大小所制约,种群的不同世代和同一世代的不同个体一样存在生长补偿作用,以及瞬时生长率与肥满系数之间有着明显的对应关系。所取得的有关参数值可以应用于渔业估算。  

STUDIES ON SEVERAL ASPECTS OF GROWTH OF SILVER CARP AND BIGHEAD CARP IN LAKE DONGHU, WUHAN

Silver carp, Hypophthalmichthys molitrix, and bighead, Aristichthys nobilis, form the dominant fish populations in Lake Donghu. In 1979—80, the author studied the growth of silver carp and bighead carp by back calculation, including their growth patterns, instantaneous growth rates(G), differences between males and females in growth, etc. The results showed that the growth patterns of the two species can be described by von Bertalanffy growth equation pretty well, the parameter values of which for silver carp were l∞=99.8cm., W∞=17104g., K=0.3040, t0=0.4821yr.; and those for bighead carp were l∞=117.6cm., W∞=29311g., K=0.3088, to=0.5392yr. The instantaneous growth rates for the two species declined graduallly with age and varied at the same age for their various year classes to some degree, coefficients of variation for them being correlated positively with age. There were no significant sexual differences in both length and weight increases for the two species of fish. After comparing and analysing the results of this research and relevant studies, the author explained that the occurrence of growth inflexion at the age of four or so in silver carp and bighead was determined by their size rather than by their age at that time. It was observed that the effects of growth compensation existed in various year clsses of the two populations as well as in various individuals of the same year class. And in the process of growth for the two species, the changes of their instantaneous growth rates were apparently in correspondence with the changes of their condition factors(K). The parameter walues derived in this research can be applied to fishery assessment.