大口黑鲈的卵巢发育周年变化及反季节繁殖研究

STUDY ON THE ANNUAL DEVELOPMENT OF OVARY AND OUT-OF-SEASON SPAWNING IN LARGEMOUTH BASS MICROPTERUS SALMOIDES

  • 摘要: 文章研究了华中地区池塘养殖大口黑鲈(Micropterus salmoides)卵巢的发育规律, 分析了水温与光照条件变化对卵巢发育的影响, 探究了大口黑鲈反季节繁殖的方法, 旨在充分利用本地区的气候条件, 化劣势为优势, 从根本上解决本地大口黑鲈产业所面临的问题。实验采用形态学、组织学等方法比较分析了大口黑鲈卵巢发育特征, 采用人工控温和人工促熟的方法探究了温度和性激素对大口黑鲈性腺启动发育的影响。研究发现, 华中地区大口黑鲈雌鱼性腺指数(GSI)周年变化在0.63%—7.95%, 10月中旬至12月初水温由20.6℃降至11.0℃期间, 卵巢开始发育至Ⅲ期, 并以Ⅲ期越冬, 至4月中旬繁殖产卵, 5月底结束, 繁殖前约80%的雌鱼绝对繁殖力在4.5万—6.5万粒, 但受水温升高的影响, 卵巢中15%成熟卵母细胞未能产出而逐步退化, 产卵结束时仍有一半以上卵未产出(GSI为4.6%); 雌鱼GSI与肠系膜脂肪系数(MFI)、肝体比(HSI)在10月份至次年4月份呈显著负相关(P<0.05), 表明在此期间, 机体储存的营养物质部分转移至性腺, 优先保证性腺发育。在大口黑鲈反季节繁殖实验中, 采用井水水温(20±1)℃降温和控温处理的方法能够促进大口黑鲈性腺的启动发育, 经过3个月处理, 控温组雌鱼卵巢发育至Ⅳ期末, GSI达到4.06%, 而对照组雌鱼卵巢处于Ⅲ期, GSI为2.52%, 两组差异显著(P<0.05), 两组雄鱼精巢均发育至Ⅳ期末, 控温组GSI达0.89%, 对照组为0.73%, 这表明可以通过温度处理来调控大口黑鲈性腺的发育。最后针对反季节繁殖中亲本的培育方法和处理时间等进行了总结, 以期为后续培育反季节大口黑鲈提供依据。

     

    Abstract: In recent years, largemouth bass (Micropterus salmoides) aquaculture industry has developed rapidly and it has become an important aquaculture species in China. Due to the influence of climatic conditions and other factors, aquaculture development of the largemouth bass in central China is not as fast as other areas, accompanied by large price fluctuation, shortage of seedling and early sexual maturity, etc. These problems have seriously hindered the development of the largemouth bass industry in the central China region. To solve these problems to some extent, we studied annual changes in the ovarian development of largemouth bass. We analyzed the effects of water temperature and photoperiod change to ovarian development and explored the method of out-of-season spawning of largemouth bass. In the experiment, we used morphology and histology to compare the ovarian development characteristics of largemouth bass. We explored the effects of temperature and sex hormones on the development of gonads in largemouth bass through temperature-manipulation and maturation-promoting.  In the present work, we found that the annual change of female GSI in the central China region was between 0.63% and 7.95%. During the period from mid-October to early December, when the water temperature dropped from 20.6℃ to 11.0℃, the ovaries began to develop to the stage Ⅲ and overwintered with stage Ⅲ. Largemouth bass initiated spawning in the middle of April and ended at the end of May. The absolute fecundity of about 80% of the female fish before spawning was between 45,000 and 65,000 eggs, but it was significantly affected by the increase of water temperature. About 15% of the mature eggs in the ovaries fail to spawn and degenerate and more than half eggs were not spawned with 4.6% GSI after the end of spawning. There was a significant negative correlation between GSI and MFI or HSI in the female largemouth bass from October to April of the following year, indicating that during this period, the energy stored by the body was transferred to the gonads. In the out-of-season spawning experiment of largemouth bass, we used well water to adjust the water temperature to promote the initiation and development of the gonads of largemouth bass. After 3 months of treatment, the ovaries of the temperature-manipulation group developed to the end of stage Ⅳ, with GSI of 4.06% for females and 0.89% for males, while the ovaries of the control group were in stage Ⅲ, with GSI of 2.52% for females 0.73% for males. Results showed that the gonadal development of largemouth bass can be regulated by temperature manipulation. Finally, we summarized the culture methods and treatment details in out-of-season spawning, to guide large-scale out-of-season spawning of largemouth bass.

     

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