|Document Type:||Journal Article|
|Title:||Reproductive dysfunction in cultured sablefish (Anoplopoma fimbria)|
|Author:||Jose Maria Guzman, J. Adam Luckenbach, Frederick W. Goetz, W. T. Fairgrieve, Mollie A. Middleton, Penny Swanson|
|Journal:||Bulletin of Fisheries Research Agency (Japan)|
Sablefish Anoplopoma fimbria is a ground fish native to the North Pacific Ocean that is considered a promising new species for marine aquaculture in the US. However, efforts to establish sustainable production of sablefish have been constrained by the reproductive performance of females from the first-filial (F1) generation. Although some F1 females may mature after 5+ years of age, some others fail to initiate puberty in captivity. Development of methods to unblock/induce early puberty are necessary to reduce costs associated with rearing F1 female broodstock and reduce generation times for selective breeding. Current research at the Northwest Fisheries Science Center (NOAA, Seattle, USA) integrates basic and applied biology to gain knowledge on the reproductive endocrine system of sablefish and develop approaches to unblock or reduce the age of puberty in F1 female sablefish. As part of our basic line of research, we compared the pituitary gonadotropin-ovary axis in wild-caught, maturing females and 8 year-old F1 females that had never shown signs of sexual maturation. Wild-maturing females had higher levels of pituitary gonadotropin subunit and ovarian gonadotropin receptor mRNAs and plasma sex steroids compared to F1 females, which were holding at the immature, perinucleolus ovarian stage. Anecdotal evidence from sablefish farms indicates that F1 female broodstock maintained in ~4 seawater mature in captivity. We hypothesize that culture conditions that use warmer water (10-15 ) suppress the pituitary gonadotropin-ovary axis in sablefish, and ultimately block the onset of puberty.As part of our applied line of research, we conducted a series of studies to determine the ability of exogenous hormones to stimulate the reproductive axis in prepubertal F1 females. Treatments with testosterone or estradiol 17-beta (E2) increased the expression of pituitary luteinizing hormone beta subunit 40- and 185-fold, respectively, relative to control. This finding suggests that pituitaries from immature females are responsive to exogenous hormones, and that sex steroids may be an important part of a hormone therapy to stimulate the reproductive axis of F1 females. In addition, using an in vitro ovarian tissue culture system, we demonstrated that fragments of prepubertal sablefish ovaries incubated with human-chorionic gonadotropin increased the secretion of E2. This indicates that ovaries of prepubertal females are equipped to synthesize and release sex steroids critical for vitellogenesis under the appropriate hormone stimulation, and that the failure to initiate puberty is likely due to a lack of adequate gonadotropin signaling. These data provide the foundation for the development of hormone treatments aimed at inducing puberty in prepubertal F1 female sablefish.
Proceedings of the 40th UJNR Symposium held in Sapporo, Japan, October 2014.
|Theme:||Ecosystem approach to improve management of marine resources|
Describe the interaction between human activities, particularly harvest of marine resources, and ecosystem function.