鄱阳湖产银鱼的繁殖生物学

本文记述了鄱阳湖产太湖短吻银鱼(Neosalanx tangkahkeii taihuensis)、乔氏短吻银鱼(Neosalanx jordani)、雷氏银鱼(Reganisalanx brachyrostralis)等三种银鱼的成熟年龄、繁殖时期、生殖群体的体长、性比、生殖力、卵的特征等繁殖生物学资料,并记述了太湖短吻银鱼性腺成熟系数的周年变化、太湖短吻银鱼和乔氏短吻银鱼的产卵生态条件等。近二十年来鄱阳湖银鱼产量急剧下降的主要原因是产卵场遭到了严重破坏。银鱼生命周期仅一年,繁殖力强,认为加强繁殖保护、合理安排捕捞时间是恢复鄱阳湖银鱼资源的关键措施。

Reproductive biology of salangid fishes in Poyang Lake

This paper deals with the reproductive biology of Neosalanx tangkahkeii taihuensis, Neosalanx jordani and Reganisalanx brachyrostralis in Poyang Lake, the results are as follows:1.N. tangkahkeii taihuensis has two reproductive seasons, from the mid-Feb. to the mid-May and from the beginning of Sept. to the mid-Nov., in a year. N. jordani spawns from the mid-Mar. to the mid-May, And R.brachyrostralis spawns very little earlier than N. tangkah keii taihuensis. 2.All the three species have an evident second character, with a row of scales above base of anal in male. The No. of scale of N. tangkahkeii taihuensis is 14-19, N. jordani 10-16, R. brachyrostralis 18-28. 3.The body length of reproductive group:N. Jangkakkeii taihuensis re pro-ducting in spring in female is 61.5±2.5mm(n=456), male 59.9±2.3mm(u= 116), female shows greater than male in body length, (F=39.5, F_{0.01(1, 400)}=6.7). N. tangkahkeii taihuensis reproducting in fall in female 59.6±2.7mm(n=31), male 58.2±2.6mm(n =63), female also shows significantly greater than male, (F=5.61, F_{0.05(1, 80)}=3.96), N. jordani in female 38.9±2.4mm(n=443), male 38.6±2.2mm(n=347), both show no significant difference in body length, (F=2.45, F_{0.05(1, 1000)}=3.85). R. brachyrostralis in female 131.7±9.9mm(n=18), male 127.3±7.3mm(n=9). 4.Sex ratio:N. tangkahkeii taihuensis is about 1:1 before spawning, and during the reproductive season, it varies from hoar to hour.By the analysis of the process as a whole, the closer the time to the end of spawning, the less the No, of male. N. jordani is about 1:1 before spawning too, During the reproductive season the sex ratio varies greatly. 5.Ave. absolute No. of eggs and Ave. relative No.of eggs N. tangkahkeii taihuensis 1696 and 1716/g. body weight, N. jordani 317 and 1749/g. body weight, R. brachyrostralis 5129 and 1643/g. body weight. 6.The eggs of the three species fishes are adherent and sinkable, on which are some fine adherent threads, No. of threads of N. tangkahkeii taihuensis 19-37, N. jordani 12-17, R. brachyrostralis 13-17. 7.In the reproductive season the coefficient of ovary of N. tangkahkeii taihuensis is 13-16%, and that of spermary 0.27-2.63%. 8.There is ten spots of spawning site of salangid fishes in Poyang Lake, the total area is about 118 km².