ANTHROPOGENIC ALTERATIONS TO THE BIOGEOGRAPHY OF PUGET SOUND SALMON

Geologic and geomorphic history and anthropogenic influences have altered the biogeography of Puget Sound salmon, by which we mean their phylogenetics, abundance, and distribution, from individual habitat units (e.g., pools and riffles) to the regional scale (e.g., North Sound). We focus on habitat isolation and degradation but also discuss the effects of harvest practices, hatchery practices, and the introduction of non-native aquatic species. Habitat isolation and degradation at the habitat and watershed scales have altered the biogeography of Puget Sound salmon at the regional scale because different juvenile Pacific salmon species spatially segregate into different habitats in the same watershed or biogeographic range. Harvest practices have had an impact on overall abundance at the regional scale, and at the even larger Pacific Northwest scale, while hatchery practices have altered the Puget Sound salmon abundance and distribution patterns at the watershed and regional scales. Alterations due to non-native species are not as pronounced; however, these do occur at the habitat-unit scale with effects that integrate up to the watershed scale. Biogeographical information can help regional and local salmon recovery efforts by identifying and characterizing large-scale spatial and temporal variability that influence salmon abundance and distribution.