秦岭细鳞鲑早期发育观察

Early ontogenesis of Brachymystax lenok tsinlingensis

研究所用性成熟秦岭细鳞鲑(Brachymystax lenok tsinlingensis)亲鱼为野生捕获。对其进行人工繁殖,并观察其胚胎和仔鱼发育。结果表明:在水温9.31～12.80℃,受精卵历经408 h出膜,所需积温为193.35℃.d,初孵仔鱼体长为(9.64±1.03)mm。整个胚胎发育过程可划分为6个阶段(受精卵、卵裂阶段、囊胚阶段、原肠胚阶段、神经胚阶段、器官形成阶段)、26个时期。刚出膜的仔鱼体色透明,肌节明显,无游泳能力,出膜第5天体表出现大量黑色素,12 d后卵黄囊开始消失,46 d的仔鱼各鳍条与幼鱼相似,出现幼鲑斑。通过探讨水温、溶氧和水质等对秦岭细鳞鲑早期发育的影响,建议秦岭细鳞鲑人工繁殖的水温不宜超过14℃,最适宜水温应控制在6～10℃;孵化水体DO应在6.00～8.55 mg/L,如果低于这个水平将会导致发育迟缓、坏死或是出膜幼苗畸形。本研究旨在为秦岭细鳞鲑的人工繁殖和鱼种培育提供科学指导。

Sexually mature Brachymystax lenok tsinlingensis were caught from the wild and, after artificial fertili- zation, embryonic and larval development were investigated. Larvae of mean body length （9.64 ± 1.03） mm hatched 408 h after fertilization. The total accumulated temperature of embryonic development was 193.35℃d at a water temperature of 9.31-12.80℃. We defined six broad stages of embryogenesis （zygote, cleavage stage, blastula stage, gastrula stage, neurula stage, and organ formation stage）, which included 26 minor periods. The hatching larvae had a transparent body with clearly visible sarcomeres, but with limited swimming capability. Five days after hatching, a patch of melanin appeared on the body surface. The yolk sac began to disappear 12 days after hatching and parr markings started to appear after 46 days, at which stage the fins of the larvae resembled those of young fish. The morphological characteristics of the embryos and larvae are described and the factors affecting ontogenesis of the early life stages of Brachymystax lenok tsinlingensis, including water temperature, dissolved oxygen and water quality, are discussed.