Sex determination in salmonids

Members of the salmonid family are present worldwide and many of them are species of major importance for aquaculture, wild stock fisheries or recreational sport fisheries. Sex determination has been well studied in this fish family, because of the importance of a better sex control in aquaculture and also because salmonids can be excellent research models. All salmonid species in which sex determination has been studied in details thus far belong to the Salmoninae subfamily (mainly salmons, trouts, and chars) and in all these species, a male heterogametic sex determination system (XY/XX) has been described. Genetic linkage groups harboring the master sex determining gene (SEX) have been identified in several species and the comparison of these SEX linkage groups demonstrated a complete absence of synteny between SEX and the associated microsatellite markers among different species. This lack of synteny of SEX has been hypothesized to be, either the result from a translocation of the SEX locus region containing the same sex determinant to different linkage groups, or an indication that the master sex determinant gene differs among salmonid species. This presentation will review some of the available published knowledge on sex determination in salmonid species along with some recent results obtained in our laboratory that shed new light on these different hypotheses.