Feeding and prey-selection of wild Atlantic salmon post-smolts

The diet of post-smelt Atlantic salmon Salmo salar, caught in the Trondheim sfjord and Frohavet in central Norway, based on stomach contents analysis, showed a gradual change during migration fi om the river to the estuary, fj ord and coastal areas. Post-smells caught in the estuary had eaten intertid al gammarid amphipods. while post-smelts caught further seawards preyed upo n available marine prey such as Calanus spp., adult euphausiids and fish la rvae. Tile frequency of adult insects was high in all post-smelt stomachs. The gradual change in diet suggested that feeding conditions in the early m arine phase were important for post-smelt survival and growth. With the exc eption of the copepods, there was no overall similarity between species com position of the plankton samples and the stomach contents. Although the hyp othesis that the post-smolts are opportunistic feeders cannot be rejected, the composition of the stomach contents suggests a possible selectivity of advantageous prey. (C) 2001 The fisheries Society of the British Isles.