鸭绿江水系唇胚胎发育、仔鱼饥饿及其不可逆点

Embryonic development,experimental starvation,and the point of no return of Hemibarbus labeo(Pallas) in YaLu River

采用人工授精方法,获得3批次鸭绿江水系唇(Hemibarbus labeo Pallas)受精卵,对胚胎发育过程进行观察和描述,研究饥饿对初孵仔鱼的生长、形态和行为的影响,确定不可逆点(PNR)。结果表明:鸭绿江水系唇成熟的卵细胞为圆形,米黄色,卵径为(1.94±0.13)mm。受精卵具有弱黏性,卵径为(3.07±0.12)mm。在水温14～24.5℃,胚胎发育共历时约94 h 2 min,主要发育时期包括胚盘期、卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期。初孵仔鱼全长(8.07±0.27)mm,卵黄囊体积为(0.55±0.12)mm3;对照组仔鱼6日龄时卵黄囊基本全部被吸收;在13日龄时,其全长和体质量分别为(12.58±1.03)mm和(0.010 8±0.002 2)g;在24日龄时,其全长和体质量分别为(17.21±0.99)mm和(0.0237±0.0054)g;全长和体质量分别与日龄之间呈正相关,其相关系数分别为R2=0.982 6和R2=0.963 6。与对照组相比,饥饿仔鱼在6日龄时全长和体质量开始出现负增长,其13日龄时的全长和体质量分别为(9.32±0.47)mm和(0.002 2±0.000 5)g。不可逆点研究结果表明,鸭绿江水系唇仔鱼从5日龄时开始摄食,初次摄食率可达65%,在7～10日龄达最高摄食率(100%),出膜后第12～13天进入PNR期,并于14日龄全部死亡。

Hemibarbus labeo Pallas in the Yalu River and its tributaries is a promising and emerging aquaculture population in northeast China. However, the wild population of H. labeo in the river has declined recently. We studied embryonic development, the effects of starvation, and the point of no return （PNR） of H. labeo broodstocks selected from the Yalu River and its tributaries. Three batches of fertilized eggs were produced by artificial spawning. Mature eggs were spherical, ecru, and （1.94±0.13） mm in diameter. Fertilized eggs were spherical, adhesive, and （3.07±0.12） mm in diameter. At 1424.5℃, normal embryonic development using 94 h and 2 min to progress through one-cell, cell division, blastula, gastrula, neurula, and organ formation stages. Newly-hatched larvae were （8.07±0.27） mm in total length and the yolk sac was （0.55±0.12） mm^3 in volume. The yolk sac had absorbed completely at 6 days post-hatch （dph）. The total length and body weight of the control group （feeding 2 times everyday ） had increased to（12.58±1.03） mm,and （0.0108±0.0022） g, respectively by 13 dph and by 24 dph to （17.21±0.99） mm and （0.0237±0.0054） g, respectively. Total length （R^2=0.9826） and body weight （R^2=0.9636） in experimental groups were both positively correlated to dph in the control group. In contrast, both total length and weight of the starved larvae began to decrease after absorption of the yolk sac at 6 dph, declining to （9.32±0.47） mm and （0.0022±0.0005） g, respectively, at 13 dph. Control larvae started to feed at 5 dph, at which time the feeding rate was 65%; 100% were feeding at 7 to 10 dph. Starved larvae suffered from PNR at 12-13 dph, and all died by 14 dph. Understanding embryonic development and knowing the effects of starvation will be important to artificially propagating H. labeo and in fish ecology and fisheries biology. Our research will play a key role in artificially propagating large numbers of individuals to augment the wild population and its recruitment deficits.