全人工繁殖西伯利亚鲟仔稚鱼发育的异速生长

Allometric growth of artificial bred Siberian sturgeon Acipenser baeri larvae and juveniles.

西伯利亚鲟(Acipenser baeri)是中国主要的淡水养殖对象之一,目前已经实现了苗种的全人工繁殖,为了改善西伯利亚鲟苗种培育技术,采用Image-Pro Plus 5.1软件显微拍照并对仔稚鱼的可量性状进行测量和数据处理,研究了全人工繁殖西伯利亚鲟仔稚鱼(0～53日龄)发育的异速生长及器官优先发育在早期生存和环境适应性上的意义。结果表明:在9、28、37日龄时分别出现3个全长生长拐点。因此,全长的生长可以分为4个阶段,每个阶段的平均增长率分别为0.83、0.79、2.68和1.71mm.d-1,其中第3个阶段的生长率明显高于其他阶段;体质量的增长可以用Gaussion方程进行拟合,相关系数R2=0.99;全长(FL)与体质量(BW)的关系为BW=0.2×10-5(FL)2.72,为负异速生长;在早期发育过程中,仔鱼的许多关键器官的大小均存在异速生长现象,眼径在3～4日龄时,最先达到生长拐点,这意味着眼部是优先发育的,使其在出膜后就能有效地躲避敌害;口宽在17～18日龄时出现拐点,此时随着感觉器官和各鳍的不断完善,主动摄食能力不断加强;胸鳍、背鳍、臀鳍的长度也分别在16～17、13～14、21～22日龄时出现生长拐点,标志着其游泳能力已比较完善,可以有效地躲避敌害和获得食物,为其早期的生存提供了保障。在育苗生产实践中,可以根据生长和发育的阶段性和优先性,适时地和针对性地创造必要的生长发育条件,保证其重要器官得到优先发育,提高早期的成活率。

Siberian sturgeon Acipenser baeri is one of the most popular fresh water aquaculture species in China, and its artificial spawning is succeeded. In order to provide information that may improve fry rearing techniques, the allometric growth of A. baeri from newly hatched larvae （ age, 0 day） to 53-day old juveniles and the significance of priority development of some organs were studied by using digital photomicrography and computer software （Image-Pro Plus 5.1 ） to measure and analyze the growth characteristics. The results showed that there were 3 inflexion points of full body length （FL） increase occurred at the ages of 9, 28 and 37 days, and thus, the FL increase might be divided into 4 periods. The mean FL increase rate of each period was 0. 83, 0. 79, 2.68 and 1.71 mm · d^-1, respectively, with that of the third period being significantly higher than those of the rest periods. The relationship between body mass （BW） increase and age could be characterized by Gaussion equation （ correlation coefficient R^2 = 0.99 ）. The relationship between BW and FL was BW =0. 2 × 10^-5 SFL2. 72, which meant that the body mass of the larvae and juveniles had a negative allometric growth. During early development, some important organs also grew in allometry. The eye diameter increase firstly reached to the inflexion point at the age of 3-4 days, which might infer that eyes had priority to develop, and thus, young fish might have ability to escape from predators immediately after hatching. Mouth width increase reached to the inflexion point at the age of 17-18 days, which implied that active feeding enhanced hereafter. The growth inflexion points of pectoral fin, dorsal fin, and pelvic fin were at the ages of 16-17, 13-14, and 21-22 days, respectively, indicating that the swimming ability of young fish improved since then. These priority developments of important organs might help fish with active feeding and escaping from predators as early as possible, and thus, a higher survival rate might achieved during early development. To improve the artificial fry rearing techniques of A. baeri, specific conditions should be provided in time, according to the periodicity and priority of organ development, and consequently, important organs might have priority to develop normally, and the survival rate of early life stage might increase.