Feeding Response of Atlantic Salmon (Salmo salar) Alevins in Flowing and Still Water

Abstract

Atlantic salmon (Salmo salar) alevins presented with lake zooplankton in still water readily consumed prey items, but only if the prey were nearby and moving. Feeding was initiated from the bottom or from midwater, but no search or pursuit behavior was noted. Stomach analyses of alevins exposed to lake zooplankton assemblages for 3 h in still and flowing (7.2 cm∙s⁻¹) water revealed that the two groups consumed similar diets, but that the still-water group had a greater total food consumption. We conclude that for alevins to feed successfully, food need not be carried in a water current, but that motion of the prey is necessary. This motion can be provided by water current or by the prey. The role of prey motility in the feeding of young salmonids is briefly discussed. Key words: Atlantic salmon, alevins, feeding, water current