Marine feeding of anadromous Salmo trutta during winter
Abstract:Juvenile and adult anadromous trout Salmo trutta utilize the sea for feeding during the winter in the Skagerrak. This finding conflicts with the traditional view that anadromous trout overwinter in fresh water. Adults, just prior to spawning, were captured at sea in October to December, and spent fish were caught at sea from October to April, showing that the fish may leave the stream and move to sea just after spawning and spend the winter there. During mid‐winter (January to February), the feeding probability (chance of finding a fish with food in its stomach) increased markedly with increasing body length, with no similar effect during early and late winter (October to December and March to April). Among individuals with food in their stomach (72·5%), there was no evidence for variation in feeding intensity [stomach fullness = (mass of stomach content)(fish body mass)−1] among early, mid‐, and late winter.
Document Type: Regular Paper
Affiliations: 1: Institute of Marine Research, Department of Coastal Zone, Flødevigen Marine Research Station, N-4817 His, Norway, 2: Norwegian Institute for Nature Research, P. O. Box 736 Sentrum, N-0105 Oslo, Norway
Publication date: January 1, 2004