Seawater adaptation in atlantic salmon (Salmo salar L.) at different experimental temperatures and photoperiods

A study was made of the effect of gradually increasing day length at different temperatures on the smolting process and on growth of Atlantic salmon during smolting.The experiment consisted of ten experimental groups: a combination of three photoperiod- with three temperature-groups and a tenth control group.Size was found to be the most important factor in seawater adaptation of underyearling Atlantic salmon. Optimal growth in the experimental temperature and photoperiod regimes occurred at 15°C and at the photoperiod with the longest period of increasing day length.At the time for seaward migration, the most pronounced effect of photoperiod on seawater adaptation occurred at 11°C. At this temperature there was a significantly higher percentage of survivors at the photoperiod with the longest period of increasing day length.