Water temperature manipulation can induce oocyte maturation and ovulation in the common Japanese conger, Conger myriaster

摘要: Abstract To develop seed production techniques for aquaculture of the common Japanese conger, Conger myriaster , we attempted to induce ovarian maturation and ovulation without exogenous hormone treatment examined changes in steroid hormones understand endocrine condition fish during their process. Juveniles caught November 2001 (20 30 cm total length) were reared 1.5 years seawater at temperatures ranging from 10 20 °C before experiments. Then, 141 randomly selected female eels (58 82 cm maintained a water temperature 6 °C April 2003 March 2004. The initial GSI values (5.0 12.0) oocyte diameters (300 400 μm) recorded had increased maximum 30.0 650 μm, respectively, end experiment, In late December 2003, 12 with oocytes measuring over 600 μm diameter divided into an elevated group 6 10 °C control 43 days. mean significantly, one (estimated GSI, 47.0) ovulated eggs average 995 ± 46 μm on 41st day 10 °C, contrast, showed no significant diameter, ovulated. Plasma T levels, via ELISA, maturation, highest level detected migratory nucleus stage, declined after ovulation. plasma E2 was high levels vitellogenic exhibiting value present study demonstrates that conger could be achieved through manipulation.