不同养殖条件下滩头雅罗鱼性腺发育的组织学研究及生长比较

Histological studies on the gonadal development and growth comparison of Tribolodon brandti in different culture conditions

采用组织切片技术对滩头雅罗鱼(Tribolodon brandti)性腺结构、弱碱和淡水性腺发育、产卵时间及类型进行了研究。滩头雅罗鱼精巢为典型的小叶型结构,共可分为6个时期。按照卵巢外形特征和生殖细胞类型,卵巢可分为6个发育时期,对应卵细胞6个时相。研究表明,性成熟的滩头雅罗鱼在9月末性腺发育到第Ⅲ期,并以Ⅲ期越冬。而未达到性成熟的幼鱼(2+龄)性腺发育到Ⅱ期,并以Ⅱ期越冬。性成熟的雄鱼在4月末或5月初性腺发育到第Ⅴ期,雌鱼在5月中下旬或6月初才能发育到第Ⅴ期,雄鱼性腺发育快于雌鱼。2~3龄个体在淡水或弱碱水环境中养殖,性腺发育时相并无明显区别。弱碱水2+龄群体体重显著高于淡水同龄群体,然而3+龄群体在弱碱水和淡水中体重没有显著差异。同时,弱碱水和淡水中的同龄雌、雄之间体重变化存在差异。在性腺发育周期中,雌、雄的平均肥满度在1.313~1.697之间波动。随性周期变化,雄性从II期开始性腺指数显著上升;雌性性腺指数在不同发育时期都存在显著差异,在V期最大为14.22。滩头雅罗鱼性腺发育高峰期一年只出现一次,为一次性产卵类型。

Using the histological methods,the gonadal development,structures of gonad,spawning time and type of reproduction in Tribolodon brandti were studied. The testes of T. brandti have typical lobular structures,and can be divided into six developmental stages. According to the characteristics of the ovaries and the types of ovarian germ cells,the oogenesis process can also be divided into six developmental stages. The microscopic observation showed that the gonadal development of sexual mature T. brandti differentiated to stage III at the end of September,and stayed at the phase III in the winter period. While the gonadal development of immature juveniles age 2＋was at the phase Ⅱ and remained such stage during the winter period. In the late April and early May,gonadal development of sexual mature males differentiated to the phase V,but in the females it was until late May or early June that they reached to the developmental phase V. Taken together,gonadal development of the males was faster than that of the females. No significant difference was observed in the gonad development of 2-3-year-old juvenile cultured in either fresh water or weak alkali water environment.The body weight 2＋-year-old group in the weak alkali water were significantly higher than that in the fresh water,but no significant difference was found between 3＋-year-old groups reared in weak alkali environment and those in fresh water. Meanwhile,significant differences of body weight existed between females and males in the weak alkali as well as in the fresh water. In the gonad development cycle,the average condition factor of female and male ranged from 1. 313 to 1. 697. During the sexual cycle,the male gonad index began to rise significantly from the II period,while the female gonad index was significantly different among development periods,with the peak value of 14. 22 in the period of V. The conclusion could be drawn that the gonadal development peak of T. brandti appears only once a year,the ovary is partial synchronic,and this species is iteroparous.