长江口长吻鮠人工繁殖研究

A Study on Artificial Reproduction of the Long-Snout Catfish Leiocassis longirostris (Günther) in Estuary of Yangtse

长江口附近于5、6月间有不少性腺成熟的长吻鮠。捕捞这些性成熟个体,进行人工催产,可以获得鱼苗,此项工作在国内是首次成功。长江口长吻鮠进入生殖年龄的个体,体重为2.50士0.35公斤,体长为60.00士1.41厘米,年龄为4龄。雌亲鱼的卵巢处于Ⅲ～Ⅳ期过冬,春未夏初发育加快,至5月下旬～6月上旬性腺已趋成熟,卵巢成熟系数(GSI)为0.0485±0.0051,卵径2毫米左右,每千克体重怀卵量约为1.5万粒左右,每克卵巢平均含卵336.5±40.3粒。雄亲鱼的精巢GSI约在0.0022。采用鲤鱼垂体(CPG)和LRH-A混合注射,获卵2.0万粒左右;人工授精的受精率为52.3%。在水温22～25℃条件下,经51～59小时孵化出苗。试验证明,从长江口捕获的性成熟亲鱼,可以直接用来催产繁殖鱼苗,从而为开发长吻鮠人工养殖、资源增殖、人工放流,解决了提供苗种的技术课题。

The long-snout catfish Leiocassis longirostris (Gunther) with matured gonads was found in estuary of Yangtse from May to June. It was the first time to obtain the fry through induced spawning of the breeders caught from Yangtse estuary. The matured individuals were 4 years-old, with 2.50±0.35 kg in body weight, 60.00±1.41 cm in body length and its ovary was on the stage of Ⅲ-Ⅳ during winter, The ovaries developed gradually at the end of spring and early summer, and almost matured from late May to June with a gonadal somatic index (GSI) of 0.0485±0.0051. The diameter of oocyte was about 2mm. The fecundity of per kg body weight were approximately 15000 eggs and the mean number of eggs was 336.5±40.3 per gram ovary. GSI of testes was approximately 0.0022. A combinative injection with LRH-A and pituitary gonadotropin of carp (CPG) was used during induced spawning. The fertilization rate was 52.5%. It took 51-59 hours for the eggs to hatch out at a water temperature of 2O～25℃.