Patterns of density-dependent growth in juvenile stream- dwelling salmonids

Literature data for 19 populations from 16 different studies of six species of stream-dwelling salmonids were analysed to test the hypothesis that density-dependent growth is stronger at low rather than at high population density. Fifteen of 19 populations showed evidence of a significant decrease in growth rate with increasing density. In 11 of these 15 populations, the pattern of density-dependent growth was better described by a negative power curve than by a linear regression (i.e. Akaike Information Criterion, AIClinear AICpower> 2), whereas only one population was better described by a linear regression than by a negative power curve; three populations were adequately described by both models (AIC < 2). In 10 of the 11 populations that were best described by a negative power curve, most of the decrease in growth rate occurred at population densities <1 fish m2, when space limitation is unlikely. This analysis provides broad support for the hypothesis that density-dependent growth in stream salmonids occurs primarily at low population densities, probably due to exploitativ