Life history differences parallel environmental differences among North American lake trout (Salvelinus namaycush) populations

Abstract

Lake trout ( Salvelinus namaycush ) exhibit substantial life history variation range-wide and at a local scale. This study addresses two hypotheses that have been proposed to account for this: (i) over the zoogeographic range, climatic conditions are associated with life history differences; and (ii) within smaller geographic regions, physical lake attributes are associated with life history differences. Multivariate statistics (Procrustean analysis and canonical correlation analysis) identified a strong, range-wide association between climate and life history variables. Colder climates were associated with slower prematuration growth, older age at maturity, and increased longevity. Winter conditions were also important; longer, warmer winters were associated with slower prematuration growth, smaller maximum sizes, and increased weight at a standard length of 425 mm. In southern populations, these general trends were further modified by physical lake attributes. High productivity lakes had lake trout with faster prematuration growth and larger maximum sizes; deeper lakes were associated with larger maximum sizes and later ages at maturity; and larger lakes were associated with slower prematuration growth, greater longevity, and larger maximum sizes. This study identifies abiotic variables that should be incorporated into existing lake trout management models, thus extending their applicability range-wide and permitting them to deal with possible impacts of climate change.