四川华鳊胚胎发育观察

Embryonic Development of Sinibrama taeniatus

四川华鳊(Sinibrama taeniatus)是长江上游特有的小型鱼类,由于近年来受河道采砂、水利工程建设、环境污染和滥捕等多种因素影响,其资源量持续下降,通过探究其胚胎发育规律,能为其后续人工繁育提供参考。从2014年5月起,在大渡河下游流域收集四川华鳊亲鱼进行池塘人工驯化培育。2016年8月,筛选出雌鱼90尾,体重(60.40±7.83)g,全长(16.28±0.62)cm;雄鱼30尾,体重(31.93±3.77)g,全长(13.90±0.64)cm,进行人工催产和人工干法授精,在溶氧充足的微流水中孵化胚胎,水温范围控制在22.3~23.0℃,用体视显微镜对不同发育阶段的胚胎细胞进行连续观察和记录。结果表明,四川华鳊在池塘驯养条件下性腺发育成熟,可开展人工繁殖,受精卵呈圆球形,浅黄色,具弱粘性,吸水后卵径为(2.11±0.04)mm,卵周间隙为(0.72±0.01)mm;在水温(22.0±0.7)℃的条件下,受精卵发育经过42h21min孵化,总积温931.7℃·h,发育过程可分为受精卵胚盘、卵裂、囊胚、原肠胚、神经胚、器官形成以及孵化出膜7个阶段;初孵仔鱼全长(2.91±0.05)mm,肌节数为24对,具心跳和血液循环,仔鱼静卧水底,极少活动,偶尔窜游。四川华鳊胚胎发育与亲源关系最近的鲂属鱼类表现出高度一致性,该研究可为四川华鳊规模化人工繁育及其他长江上游特有鱼类的资源增殖保护和开发利用提供理论参考。

Sinibrama taeniatus is a small fish endemic to the upper reaches of the Yangtze River.In recent years,wild populations of S.taeniatus have declined sharply as a result of cascaded hydropower stations,sand excavation,over fishing and environment pollution.In this study,the embryonic development of S.taeniatus under controlled laboratory conditions was described and illustrated.Parental stock was collected in the lower reaches of Dadu River in May 2014and pond reared.In late August 2016,90females[(16.28±0.62)cm,(60.40±7.83)g]and 30males[(13.90±0.64)cm,(31.93±3.77)g]were treated with oxytocin to induce spawning.Zygotes were obtained by dry fertilization and incubated under slowly running water at 22.3-23.0℃and adequate dissolved oxygen.A stereoscopic microscope was used to observe and record embryonic development from fertilization to larval release from the membrane.Results showed that the gonads of S.taeniatus matured during pond domestication and artificial reproduction could be carried out.The fertilized eggs were ovate and yellow,demersal and weakly glutinous,with an average diameter of(2.11±0.04)mm and average perivitelline space of(0.72±0.01)mm after swelling.The entire embryonic development period was 42h21min at(22.0±0.7)℃and the maximum cumulative temperature was 931.7℃·h.The embryonic development process consisted of seven stages:fertilized egg,cleavage,blastula,gastrula,neurula,organ development and the release of newly hatched larvae from the membrane.The newly hatched larva were(2.91±0.05)mm,had 24sarcomeres and blood circulation and heart pulsation began.The eyes of the larvae were pale black and the head was perpendicular to the body.The larvae reposed at the bottom of the water and displayed weak activity.The embryonic development of S.taeniatus was highly similar to that of its closest Megalobrama relatives.This study provides basic information for large-scale artificial breeding of S.taeniatus as well as resource protection and utilization of species endemic to the Yangtze River.