长江南源小头裸裂尻鱼人工繁殖技术

小头裸裂尻鱼为我国特有鱼类,仅分布在青藏高原,是水生态系统中的关键鱼种。2020年6月,以在长江南源当曲海拔4 819 m处选取的16尾(2雌14雄)性腺处于V期的小头裸裂尻鱼为研究对象,在海拔4 767 m处原位孵化1.1万受精卵。孵化条件为:日节律众数水温区间为8.3~16.0 ℃,溶解氧＞5 mg/L,pH值为(7.7±0.2),盐度为(0.13±0.1)psu,氨氮浓度＜0.1 mg/L,总悬浮固体含量为(3±0.5)mg/L。结果表明:亲鱼性腺成熟度佳,V期卵径为(2.4±0.2) mm,雄鱼全长约为雌鱼全长((40.3±3.5)cm)的1/2,体重约为雌鱼体重((435.2±67.5)g)的1/10。授精水温为16.3 ℃,受精率为99%;孵化第10 天(238~240 h)积温3 057 h·℃时发生大规模出膜;实施关键出膜水温19 ℃后,出苗率达到80%,出膜仔鱼长度为0.9~1.0 cm。人工繁殖技术的突破,有利于该鱼类的自然种群恢复、人工保种,以及研究其胚胎发育的物候响应。

Artificial Propagation of Herzensteinia microcephalus (Herzenstein, 1891) in the Southern Headwaters of the Yangtze River

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.