DEVELOPMENT OF THE MATURATION-INDUCTION AND OVULATION-INDUCTION METHOD IN CULTURED TIGER PUFFER TAKIFUGU-RUBRIPES BY HORMONAL TREATMENTS

We developed an effective method for the induction of oocyte maturatio n and ovulation in the cultured tiger puffer Takifugu rubripes by horm onal treatments, in order to supply the fertilized eggs for seedling p roduction. Ovarian biopsy just prior to the hormonal treatments reveal ed the oocyte diameter and developmental stages of the oocytes. A lute inizing hormone-releasing hormone analogue (LHRH-a) cholesterol pellet (400 mu g/kg) implantation successfully induced oocyte maturation for three-year-old cultured tiger puffer which had yolk accumulated ovari es. Thereafter, single injection of HCG (500 IU/kg) combined with chum salmon pituitary (SP) homogenate (7 mg/kg) was applied to the fish to synchronize ovulation among fish. Ovulation mainly occurred between 9 6 and 120 hours after HCG+SP injection. Thus, a technique for obtainin g eggs of high quality from the cultured tiger puffer was developed.