关键词: 小头裸裂尻鱼, 性腺成熟, 人工繁殖技术, 水温节律, 关键出膜水温

Abstract: Herzensteinia microcephalus (Herzenstein, 1891) is endemic to China and only lives in the Qinghai-Tibetan Plateau. It is a key species in the aquatic ecosystem. However, artificial propagation technology has not yet been developed until June 2020 when sixteen parent fish (2 females and 14 males) with gonads in matured V stage were selected at 4 800 m a.s.l in the Dangqu River, the southern headwaters of the Yangtze River. Eleven thousand fertilized eggs were incubated at 4 767 m in-situ in daily rhythm with water temperature range of 8.3-16.0 ℃, dissolved oxygen greater than 5 mg/L, pH (7.7±0.2), salinity (0.13±0.1) psu, ammonia nitrogen less than 0.1 mg/L, and total suspended solids (TSS) concentration (3±0.5) mg/L. Results showed that the parent fish matured well, the oocyte diameter at stage V was (2.4±0.2) mm, the total length of the male fish was about 1/2 of the female (40.3±3.5) cm, and the weight was about 1/10 of the female (435.2±67.5) g. The fertilization rate reached 99% when the water temperature for fertilization was 16.3 ℃. On the 10th day of incubation (238-240 h), when the accumulated temperature was 3 057 h·℃, large-scale egg envelope-breakdown occurred. The total length of the newly hatched larvae was 0.9-1.0 cm, and the hatching rate reached 80% after the implementation of the critical water temperature 19 ℃ as egg envelope breakdown triggering. The breakthrough of artificial propagation technology is conducive to the natural population restoration, conservation of the Herzensteinia microcephalus and to reveal embryonic response of Herzensteinia microcephalus to the climate warming in the Qinghai-Tibetan Plateau.

Key words: Herzensteinia microcephalus, mature gonad, artificial propagation, water temperature rhythm, key water temperature for egg envelope-breakdown