Annually, increasing antropogenic impact on environment results in a considerable aggravation of the ecological condition and extinction of many species of organisms and a decrease in the abundance of Acipenseridae fish family in the Caspian Sea. Therefore cryopreservation of the sturgeons sperm has become on urgent problem. Thus cryopreservation of gametes and embryos is considered to be one of the ways to preserve gene pool of the fish. In this research the broodfish originated from Turkman and Tazabad fish capture station in south of Caspian Sea. They were stored in fish breeding pond with river water flow for one week in shahyd Marjani and shahyd Rajaei fish farms. The males of broodfish were injected intramuscularly with action dryed sturgeon pituitary at doses of 2.5 mgkg-1 body weight. The sperm was collected 12h later, by a sound connected to 50ml syringe. Activity of fresh sperm wa determined by mean of microscope after its dilution by water. Then the fresh sperm was diluted by cryoprotective medium in proportion of 1:10 containing 0.1 M of Tris-HCl buffer, pH 8.6, 2% dimethyl sulphoxide, 25% yolk of chiken egg and 0.04 M saccharrose. sperm diluted using this way was poured into 1ml syringe and frozen according to two method: immediately or gradually. After 12h to 205h activity of frozen-thawed sperm was determined and used for fertilization. As the result showed that the percentage of foucoundation (success of fertilization) was 27 and the percentage of yolk sac embryo stage was 16.

Iranian Fisheries Science Research Institute

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