Feeding habits of wild and escaped farmed Atlantic salmon, Salmo salar L.,in the Northeast Atlantic

The stomach contents of 2992 wild and 863 putative escaped farmed Atlantic salmon caught on floating long-lines in a Faroese research fishery in the l ate autumn (November-December) and winter (February-March) in the Northeast Atlantic (63-66 degreesN and 1-10 degreesW) during three consecutive fishi ng periods 1991/1993-1994/1995 were analysed. Hyperiid amphipods of the gen us Themisto. euphausiids and mesopelagic shrimps are important sources of f ood for salmon in the autumn period and various mesopelagic fish as lantern fishes, pearlsides and barracudinas become equally important during the la te winter period. The occasional presence in the stomach of larger fish suc h as herring, blue whiting and mackerel is not considered to be evidence th at these fish are a main source of food for salmon in the sea north of the Faroes. The proportion of stomachs containing food was significantly lower during autumn (53%) than during winter (78%). However, temperature-dependen t evacuation rates could partly explain the apparent lower stomach content during the autumn since the average ambient sea-surface temperature is 7 de greesC in autumn compared to 3 degreesC in winter. There was evidence of se lective foraging. Fish were preferred over crustaceans, and amphipods were chosen over euphausiids. Large salmon (3+SW) tended to be more piscivorous than smaller fish. There was no difference in condition factor, number and weight proportions of prey, or in diet between wild and escaped farmed salm on, which suggests that escaped farmed salmon adapt well to the "wild" life in the ocean. (C) 2001 International Council for the Exploration of the Se a.