长江水系鲢鱼和珠江水系鲢鱼的生长差异

ON THE GROWTH RATE OF SILVER CARPS FROM DIFFERENT SOURCES OF CHANGJIANG RIVER AND ZHUJIANG RIVER

为考察和比较不同水系鲢鱼的生长特点,把来源不同的四种鲢鱼,即长江野生鲢鱼、长江流域人工繁殖鲢鱼、珠江野生鲢鱼和珠江流域人工繁殖鲢鱼,分组在精养成鱼池、网箱及自净式水池中混养,进行同一环境中和不同环境中的生长速度的比较研究。试验鱼从2月龄起观察到16月龄止,平均个体大小从全长12厘米,体重16克起到39厘米、605克止。试验结果表明,来源于两水系的鲢鱼的生长速度有着规律性的差异。不论野生的还是人工繁殖的,珠江鲢鱼的早期生长速度都比长江鲢鱼略快,但后期的生长情况却相反,长江鲢鱼的生长速度变得比珠江鲢鱼快,在第二年的养殖中越来越显出长江鲢鱼的生长优势。第二年1月份试验开始时,体重比珠江鲢鱼小的长江鲢鱼,至11月份时却超过了珠江鲢鱼。在第二年养殖过程中,四种不同来源鲢鱼体重增长率的大小顺序是长江野生鲢鱼>珠江野生鲢鱼>长江人工繁殖鲢鱼>珠江人工繁殖鲢鱼。

An attempt has been made to compare the growth rate of silver carps from different sources. They are, a group of wild silver carp and a group of domesticatedsilver carp from Changjiang River; and a group of wild silver carp and a group ofdomesticated silver carp from Zhujiang River. Experiments were carried out in fishrearing ponds, net cages and self-purification round ponds. In each experiment thefish of 4 groups reared were mingled and each group was marked by fin-clipping.The fish were reared from 2 months to 16 months old, the total length were from12 cm to 39 cm, and the body weight were from 16 g to 605 g.Results showed that a regular differerence of growth rate existed within the 4groups of silver carp. In spite of wild or domesticated, the two groups from Zhujiang River grew fast in the first ywr, then slowed down in second year. On the contrary,silver carp from Changjiang River appeared slow in the first year and rapidly progres-sed in the second year. Consequently a surpassing weight of 28--66 g over ZhujiangRiver silver carp was produced. The order of growth rate of the 4 groups were:Changjiang wild silver carp>Zhujiang wild silver carp>Changjiang domestic silvercarp>Zhujiang domestic silver carp.