厚唇裸重唇鱼繁殖生物学

2001-2009年在黄河上游水系进行土著鱼类资源调查,对收集到的235尾厚唇裸重唇鱼开展繁殖生物学研究。研究发现,厚唇裸重唇鱼繁殖期为4-6月,盛期为5月,在繁殖季节可借第二性征辨别性别,雌鱼和雄鱼均于6龄达到性成熟,雌鱼最小性成熟体长30.8cm,体质量380.7g,成熟系数15.21%;雄鱼体长27.2cm,体质量335.7g,成熟系数10.18%。厚唇裸重唇鱼绝对怀卵量为3043～42 158粒,相对怀卵量为7.9～37.2粒/g。成熟卵径(2.1±0.1)mm,卵子数为134.9粒/g;测定了产卵场的理化因子,集群繁殖需要约8℃的水温及其他一些生态因子刺激(海拔、水流、饵料等)。

Reproductive Biology and Spawning Habitats of Gymnodiptychus pachycheilus

Gymnodiptychus pachycheilus,a cyprinid fish belonging to Schizothoracinae,inhabits in the upstream area of the Yellow River,which is an endemic fish,a small population sizes,and narrow distribution in the Tibet Plateau.Owing to environmental changes and overfishing,the population size was decreased sharply now and resource-recovery of this species becomes very urgent.Here,235 individuals were collected in the upper reaches of Yellow River from May 2001 to October 2009.The results showed that the spawning of Gymnodiptychus pachycheilus population took place from April to June,mainly on May.Individual females spawned in the 30.8 cm or more in body length and body weight more than 380.7 g,with gondosomatic index of 15.21%,and male body length of mature individuals in more than 27.2 cm and weighing more than 335.7 g,with gondosomaticindex of 10.18%.Either females or males,the initial maturity was observed at the age of 6 or more.Mature eggs was(2.1±0.1) mm in diameter,and the number of eggs per gram was 134.9.Absolute fecundity of 3043~42158,and relative fecundity of 7.9~37.2 grains/gram were found.With the intensification of human activities in recent yearsed,many spawning ground disappeared.It was found only in the Yellow river water system of each branch,where no people reach here.Due to lower altitudes,higher temperature,and enough natural food,spawning time reached 7 to 10 days in advance.It shows it is possibility to use ex situ conservation.