Effects of water temperature and hormones on ovarian development of conger eel in Korea were investigated. Ovarian development was analyzed by measuring gonadosomatic index (GSI) and oocyte diameter with histological methods. At rearing water temperatures of 12°C, 14°C, and 16°C, GSI value increased from 3.66 at the start of the experiment to 7.44, 8.82, and 7.34 at the end of the experiment, respectively. At rearing water temperatures of 12°C, 14°C, and 16°C, egg diameter increased from 245.11-300.25 µm at the start of the experiment to 377.62-480.27 µm, 396.72-498.54 µm, and 382.29-475.69 µm at the end of the experiment, respectively. Follicular oocyte development revealed that primary yolk globule stage observed from January to March. It entered to secondary yolk globule stage in April and remained at the same stage until July. As a result of examining effects of three hormones (human chorionic gonadotropin (HCG), luteinizing hormone releasing hormone analogue (LHRHa), and salmon pituitary extraction (SPE) on ovarian development, HCG was found to be the most effective one. The progress from diapause of the secondary yolk globule stage to migratory nucleus stage of oocytes could be induced by treating fish with HCG at 1,000 IU/kg. The effect of hormone treatment on ovarian development of conger eel in Korea was the most effective at water temperature of 14°C.
Keywords: Conger eel; Conger myriaster; Exogenous hormone; Ovarian development; Water temperature.
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