Population variation in density-dependent growth, mortality and their trade-off in a stream fish

Important variation in the shape and strength of density-dependent growth and mortality is observed across animal populations. Understanding this population variation is critical for predicting density-dependent relationships in natural populations, but comparisons among studies are challenging as studies differ in methodologies and in local environmental conditions.
Consequently, it is unclear whether: (1) the shape and strength of density-dependent growth and mortality are population-specific; (2) the potential trade-off between density-dependent growth and mortality differs among populations; and (3) environmental characteristics can be related to population differences in density-dependent relationships.
To elucidate these uncertainties, we manipulated the density (0.3-7 fish/m2) of young-of-the-year brook trout (Salvelinus fontinalis) simultaneously in three neighboring populations in a field experiment in Newfoundland, Canada. Within each population, our experiment included...