Prey consumption by juvenile salmonids on the Taku River, southeast Alaska

Abstract

Stomach contents were collected from juvenile salmonids (genus Oncorhynchus and Salvelinus) from habitats on the Taku River in 1987. Differences were defined between groups of fry. A linear discriminant function (LDF) analysis was applied to prey frequencies grouped by species, habitat, and period. The analysis discriminated between: fish in beaver ponds; sockeye in side-slough sites and fish from other mainstem sites; and beaver ponds and mainstem sites. An exclusion experiment was established in a beaver pond. The diet of sockeye (O. nerka) and coho (O. kisutch) fry was sampled from allopatric and sympatric treatment enclosures. LDF analysis applied to prey categories assigned group membership between species, treatment, and period factors. A log-linear analysis yielded significant interaction effects between the treatment, habitat, and. period explanatory variables and the response, prey, confirming the influence of the presence of cogenerics on prey consumed.