Effects of diet and the vgll3 locus on male maturation and sperm traits of Atlantic salmon

Abstract

A challenge in Norwegian Atlantic salmon (Salmo salar) aquaculture is unwanted early maturation in male fish. Environmental factors such as diet and genetic factors such as the vgll3 locus, are key mediators of male maturation and reproduction. In this study, different feeding treatments, alongside the vgll3 locus, was analyzed to assess their influence on maturation and sperm traits on four-year old Atlantic salmon raised in a common-garden. This study utilized first-generation hatchery broodstocks from two Finnish populations to produce fish with different vgll3 genotypes. Fish were fed either a high fat feed or low fat feed representing a 22% reduction in dietary energy. Sperm traits were assessed using Computer-Assisted Sperm Analysis (CASA) system. Significant differences in body length were observed between populations, with Oulu River males being smaller than Neva River males. Maturation showed no significant differences in vgll3 genotypes, diet, or population. No significant vgll3 effects were found on sperm traits, but Neva River fish had significantly higher linearity and straightness, and low fat diet fish had higher average pathway velocity and curvilinear velocity estimates. Sperm traits generally performed better with a low fat diet suggesting that a low fat diet might be more beneficial for sperm quality in Atlantic salmon.