Examination of embryonic developmental stage by cannulation to synchronize the timing of parturition in black rockfish Sebastes schlegeli broodstock females
2005
Nakagawa, M.(National Center for Stock Enhancement, Iwate (Japan). Miyako Station) | Okouchi, H.
Black rockfish is viviparous and one of the important target fish species for aquaculture and stock enhancement in Japan and Korea. Because size differences in black rockfish larvae lead to increased cannibalism, preparation of a sufficient number of larvae with the same or similar daily age is necessary for efficient aquaculture. We developed a method to concentrate the parturition period of female broodstock by examining the developmental stage of embryos using cannulation and selecting females, which are predicted to have similar parturition dates. We set up two groups examined over a 3-year period: one for selected broodstock with cannulation of embryos and the other as unselected control groups. The parturition period of the selected group was significantly shorter than that of the control group and greater numbers of larvae with the same parturition date were obtained in the selected group over the 3 years of experiments. The differences between the predicted dates and the actual dates of parturition were 1 - 3 days for the day parturition began and 0 - 2 days for the day parturition ceased. These results indicate that selecting broodstock female on the basis of the inspection of the embryonic developmental stage using cannulation will enable us to obtain newly released larvae for systematic and efficient aquaculture.
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