北海文昌鱼雌鱼群体性腺发育的周年变化

Annual changes in gonad development of female Branchiostoma belcheri Gray population in Beihai, Guangxi

【目的】了解广西北海海区文昌鱼雌鱼繁殖群体性腺发育的周年变化规律。【方法】对广西北海海区文昌鱼进行连续3年的跟踪采样和观测,分别测定北海文昌雌鱼群体的体重、体长和性腺大小,计算成熟系数(GSI),并对雌鱼性腺组织切片进行显微连续观察,分析北海文昌雌鱼繁殖群体的性腺发育规律及产卵繁殖特点。【结果】北海海区雌性文昌鱼的繁殖季节从每年3月下旬开始,5～6月为繁育盛期,至7月底繁殖基本结束;在繁殖习性上,北海文昌鱼属于一年一次成熟产卵类型,一生可多次成熟产卵;在非繁育期间,北海文昌雌鱼繁殖群体中的个体性腺发育程度差异较大,存在明显不同步现象,但在繁育高峰期内个体间在较短时间内能基本趋于集中同步成熟;北海文昌雌鱼群体的个体GSI与其体重呈正相关。【结论】北海文昌雌鱼的繁育盛期为5～6月,属于一年一次成熟产卵类型,为今后开展天然海区北海文昌鱼的资源保护和人工繁殖研究奠定了基础。

[Objective]The objective of the present experiment was to study the gonad development process and reproductive behaviour of female Branchiostoma belcheri Gray population in Beihai sea area, Guangxi. [ Method ] The female Branchiostoma belcheri Gray was sampled from their population in Beihai coast of Guangxi and surveyed continuously for 3 years. The body weight and length, ovary size and gonadosomatic index （GSI） of each sample were recorded. Additionally, the gonad of female Branchiostoma belcheri Gray was used for microscopic observations. [Result]The spawning period of female Branchiostoma belcheri Gray population in Beihai was recorded to be started from last ten days of March, and attained its peak from May to June, and ended up by the end of July each year. The individuals female B.belcheri Gray in Beihai mature and spawn once in a year, and capable of continuing this process many times in its life. In non-spawning season, the ovary development in female population was found significantly asynchronous, while they could mature intensively and synchronously in a short time during peak spawning season. The GSI of female individuals in Beihai showed a positive correlation with the body weight, indicating that GSI increase or decrease simuhaneously with the increase or decrease in body weight. [Conclusion]The peak spawning season of B. beleheri Gray population was from May to July in Beihai. The results of our studies will help in studying the resources protection and artificial reproduction of B. belcheri Gray in Beihai, Guangxi.