Atlantic salmon farming depends on freshwater rearing of juvenile fish from egg hatching until they are large enough to undergo transfer to seawater, where they can grow rapidly. Because of the high salt concentrations in seawater, this requires fish to undergo pronounced changes in the gill physiology linked to retention of water and salt excretion. Variability in the success with which this physiological change is achieved is thought to be a major contributor mortality in the seawater phase of salmon production. This variability stems from a combination of how freshwater rearing is conducted and the genetic variation in salmon stocks.

In Hubsmolt we will explore the genetic aspect, focussing on a region of salmon chromosome 14, which we call the ´hub locus´. Our interest in this region stems from our recent discovery that genetic variation in this region affects how over 2000 other genes are expressed in the gill prior to transfer to seawater, which makes it particularly promising as a focus for genetic improvement of farmed salmon. 

HubSmolt therefore aims to understand how variation at the hub locus affects development of juvenile salmon in freshwater and how this links to subsequent performance when the fish are moved to seawater. To achieve this we will conduct experiments in genetically defined fish following a typical commercial rearing protocol. This will include

assessment of organ development, immune function, and responses to viral disease and handling stress. In parallel, we will also zoom in on the Hub locus on chromosome 14 to identify at a DNA-level how a single genetic region has such widespread effects on salmon development.

To meet these aims we have established strong interdisciplinary partnership between physiologists, geneticists, virologists and aqualculture experts, with backgrounds linking basic science to industry application. This ensures the academic success of the project, facilitates dissemination of practically relevant project findings.



David Hazlerigg (Principal investigator)
Alex West

Financial/grant information:

The project was awarded by the Norwegian research council under the thematic call "Hav" (ocean). ASTI director David Hazlerigg will lead the project in collaboration with NMBU, the University of Aberdeen, MOWI and NOFIMA. ASTI researcher Alex West is also a project partner and along with UiT researcher Eva-Stina Edholm. The aim is to characterise a novel genetic locus defining seawater consequences of freshwater rearing conditions in Atlantic salmon.