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Abstract
Burbot Lota lota are an emerging aquaculture species. To aid in predicting the natural and hormonal-manipulated timing of ovulation and for ensuring maximum viability of eggs at spawning, this study describes oocyte maturation of hatchery-reared burbot from vitellogenesis through ovulation. At a temperature of 4°C, visual polarization of the oil globule occurred 7–13 d preovulation. The lack of uniformity in individual oocyte development was observed and persisted until approximately 2 d before ovulation, at which point complete polarization was observed in all oocytes and a condensed blastomere was observed along the inner chorion. These preliminary observations imply that implantation of gonatotropin-releasing hormone (GnRH) decreased the final maturation stage of oocyte development by 2–4 d and may aid in initiating the maturation process, the induction of which appeared to be a threshold for either a female's progression to ovulation or nonovulation and atresia. Although additional investigation may be needed to fully maximize egg fertilization success and optimize timing related to intensive spawning practices, this study lays a foundation for further investigations and provides a reference for assessing oocyte development and predicting ovulation for this species.
Received September 2, 2011; accepted February 14, 2012
ACKNOWLEDGMENTS
Funding for this project was provided by the Kootenai Tribe of Idaho and the Bonneville Power Administration (Contracts 30729, 37267; Project 198806400). We thank Matt Neufeld of the British Columbia Ministry of Environment for supplying broodstock and all the members of the Kootenai Valley Resource Initiative for their cooperation. Special thanks are extended to Paul Anders for his input and review.