Feeding chronology of Atlantic salmon parr in subarctic rivers: consistency of nocturnal feeding

Abstract

During the ice‐free season in three subarctic rivers in northern Norway and Finland, Atlantic salmon parr Salmo salar exhibited significant diel fluctuations in stomach content weights in August and September, the largest weights being recorded consistently at 0300 hours. Accordingly, the feeding rate of the parr was highest during the night and lowest in daytime, whereas during the other periods of the ice‐free season, no pronounced diel fluctuations in food intake occurred. The consistent nocturnal feeding periodicity in early autumn in subarctic rivers may be associated with benthic feeding and an increased availability of benthic prey at night.