Density-dependent refuge use among over-wintering wild Atlantic salmon juveniles

Sheltering behaviour of wild juvenile Atlantic salmon in an indoor stream w as found to be density dependent; the proportion of fish sheltering decreas ed significantly with increasing population density. The mean number of fis h occupying refugia was less than or equal to1.5 fish per refuge even at ve ry high densities (potentially 5 fish per shelter). These results suggest t hat shelter availability has potentially important consequences for the car rying capacity for natural populations of salmon in streams.