辽河水系洛氏仔、稚鱼形态发育与生长特征

Morphological Development and Growth of Larvae and Juveniles of Fat Minnow Phoxinus lagowskii lagowskii Dybosky in Liaohe River

本文研究辽河水系洛氏Phoxinus lagowskii lagowskii仔、稚鱼形态发育和早期生长。结果表明:在18.8~27.2℃下,洛氏初孵仔鱼全长为(4.46±0.43)mm,4日龄的仔鱼鳔一室,5日龄时开始摄食,6日龄卵黄囊完全吸收,13日龄时鳔二室,32日龄时各鳍发育完成;36日龄时开始出现鳞片;58日龄时除头部外全身被鳞,进入幼鱼期。根据卵黄囊、运动器官和鳞片的变化,洛氏早期发育可分为卵黄囊期(孵出0~5d)、后期仔鱼(6~35d)和稚鱼期(36~58d)。曲线拟合表明,卵黄囊体积(V)和全长(LT)与日龄(d)均呈二次多项式关系,相关方程分别为:V=0.0063d2-0.0870d+0.2863(R2=0.8167),LT=0.0083d2+0.2351d+4.8759(R2=0.9544);体质量(W)与日龄(d)呈指数函数关系:W=0.0006e0.1317d(R2=0.9719)。

The morphological development and growth were observed and measured in larvae and juveniles of fat minnow Phoxinus lagowskii lagowskii from Liaohe River at water temperature of 18.8 to 27.2℃. The newly hatching larvae had total length of (4.46± 0.43)mm, and posterior swim bladder anlage 3 days after hatching (DAH). The initial feeding was observed in the larvae at 5 DAH. The yolk sac was completely exhausted at 6 DAH, and the larvae showed appearance of the anterior swim bladder at 13 DAH. At 32 DAH, all fins were well developed in the larvae, and scales began to be differentiated at the back of the operculum at 36 DAH, when the larvae developed into juveniles with which scales were covered the entire body apart from the head at 58 DAH. In terms of mor-phological changes in yolk sac and scale, the post-embryonic development of fat minnow may be divided into 3 stages:the yolk-sac stage(0~5 DAH), postlarva stage(6~35 DAH) and juvenile stage(36~58 DAH). The relationship between yolk volume(v) and day after hatching(d) was expressed as the equation:V=0.0063d2-0.0870d+0.2863(R2=0.8167). The relationship between total length of the fish (LT) and day after hatching (d) was described as the equation:LT=0.0083d2+0.2351d+4.8759 (R2=0.9544), and the body weight(w) and day after hatching(d) was described as W=0.0006e0.1317d(R2=0.9719).