Photoperiodic control of smoltification in anadromous salmonids

Smolting is the phenotypic transformation of juvenile salmonid fish from a freshwater resident phase (parr) to a seawater migratory phase (smolt).

The parr-smolt transformation (PST) encompasses several changes adaptive for life in seawater, of which the development of seawater osmotic tolerance is the most studied.

PST depends on seasonal timekeeping, and is initiated by declining photoperiods in the autumn prior to migration to sea, with completion of the process dependent on increasing photoperiods in the spring. The natural light-dependence of this process is of major economic importance because of its implications for aquaculture production processes.

Under the ‘Synchrosmolt’ initiative funded by the Norwegian Seafood Research Fund (FHF), and with our partners at NMBU and MOWI (Simen Sandve, Turid Mørkøre, Solomon Boisin, Bjarne Gjerde) we are taking modern genetic approaches to investigate heritable variation in photoperiod-dependent seasonal timekeeping in Atlantic salmon (Salmo salar) (ASTI Theme 2). This project involves large scale family-cross experiments and high resolution genome-wide scans to identify key loci driving genetic variation in seasonal timekeeping. The outcomes of this work will help to optimize smolt production protocols by combining optimal geneotypes with optimal photoperiodic regimes, and it will give basic genetic insight into the core seasonal timer mechanisms in teleosts (ASTI Theme 1).


David Grey Hazlerigg (Principal investigator)
Anja Striberny
Even Jørgensen (Principal investigator)

Financial/grant information:

Norwegian Seafood Research Fund (FHF)