乌江中华倒刺鲃仔、稚鱼耳石的形态发育与生长

Otolith Development in Larval and Juvenile qingbo Spinibarbus sinensis of Wujiang River

研究中华倒刺鲃(Spinibarbus sinensis)耳石的发育和生长特征,补充早期生物学资料,为进一步研究该鱼野生资源的早期生活史特征提供基础数据。在实验室养殖条件下观察了乌江中华倒刺鲃仔、稚鱼及3种耳石的形态发育过程和生长特点。结果表明,在水温(26.0±2.1)℃下,初孵仔鱼微耳石和矢耳石已经形成,星耳石在仔鱼出膜后第6天出现。在形态发育过程中,微耳石由出膜时的近圆形经卵圆形发育成贻贝形,且中心核位置偏移到前端靠近背侧;矢耳石由近圆形经卵圆形发育成箭矢状;星耳石由逗号形发育成不规则四边形。3种耳石形态发育的各阶段与鱼体发育阶段存在一定的对应关系。在生长上,仔稚鱼鱼体、3种耳石的长径和短径与日龄均呈显著的线性关系(P<0.001),鱼体全长与3种耳石长径呈现出显著的线性关系(P<0.001),仔稚鱼鱼体、3种耳石的特定生长率随日龄增加均呈下降趋势。

Spinibarbus sinensis（ commonly known as qingbo） was an important commercial fish species widely distributed in Yangtze River and its tributaries. However,wild populations have declined sharply due to overfishing and habitat destruction. Artificial breeding of S. sinensis has been successful and we studied the morphological development and growth of otoliths in laboratory-hatched larvae and juveniles of known age： first generation off-spring（ F1） of wild S. sinensis collected in Wujiang River. The results supplement information on the early life history of S. sinensis and provide base data for early life history research on wild populations. A total of 540 otoliths were collected,including 197 lapillus,198 sagitta and 145 asteriscus. Sagitta,asteriscus and lapillus were extracted,cleaned and digitally imaged using an OPTEC DV320 microphotography system. The long diameter of the otoliths,from the anterior to posterior（ D1）,and the short diameter,from the dorsal to ventral（ D2）,were measured. Results show that,at a water temperature of（ 26. 0 ± 2. 1） ℃,the sagitta and lapillus were present in newly hatched S. sinensis,while the asteriscus appeared approximately 6 days after hatching. During otolith development,the lapillus shape changed from nearly round to ovoid,and,by day 31,the ovoid had flattened on one side（ musselshaped） and the nucleus had moved to the anterior dorsal region. The sagitta was more irregular in shape： nearly round in hatchlings,changing to ovoid and finally to a long ellipse with pointed posterior and rounded anterior. The morphology of the asteriscus was relatively stable,at first comma-shaped and changing to an irregular quadrilateral,with minor differences in outline and undulant margin. The development of the three otoliths was closely related to fish development. There was a significant linear relationship between the total length of larval/juvenile S. sinensis and the long diameter of all three otoliths（ P〈0. 001）. The equations are as follows： lapillus,L = 1. 611 D1＋56. 090（ R^2= 0. 9352,n = 197）; sagitta,L = 0. 750 D1＋ 70. 971（ R^2= 0. 9375,n = 198）; asteriscus,L = 0. 651D1＋ 39. 891（ R^2= 0. 8707,n = 145）. The specific growth rate of the total body length and each otolith length exhibited a downward trend with daily age.