POWELL, M/L; KAVANAUGH, S/I; SOWER, S/A; Univ. of New Hampshire: Reproductive Hormone Concentrations in the Atlantic Hagfish Myxine glutinosa

Depletion of traditional fisheries stocks around the world has led to the development of nontraditional fisheries to replace lost income. The M. glutinosa has become the focus of a growing fishery in the North Atlantic. Currently fishermen and local agencies are attempting to draft a management proposal to maintain a sustainable fishery. A successful management plan requires an understanding of the growth and reproduction of the species. However, traditional stock assessment techniques cannot be applied to hagfish populations and even the most basic information on sex ratios and reproduction is not known. The objectives of this research are to characterize gonad development and reproductive status over 18-months to gain insight into reproduction in M. glutinosa. Three size classes of hagfish were examined (small 20-35cm, medium 35-45cm, large 45-55+cm). Gonads were examined histologically to determine sex and developmental stage. Concentrations of steroids associated with reproductive activities (estradiol and progesterone) were measured in gonad tissue incubated with pregnenolone for 48 hr at 4�C. The small group contained females and immature hagfish; true males were rarely observed. However, hermaphrodites were frequently observed in the medium size class. Mature eggs were found only in the large size class. In the large and medium hagfish progesterone concentrations decreased over time between February and June 2002. Estradiol levels peaked in January suggesting the initiation of vitellogenesis and possibly the onset of reproductive activity. This study and earlier studies from this lab support the hypothesis that M. glutinosa has a reproductive cycle that must be considered in the formulation of a management strategy. Supported by UNH/UME NOAA Sea Grant R/FMD-168.