Movement, survival, and resource use by stocked Rainbow Trout

Abstract

Non-native species introductions often have unintentional consequences. This has led to a gradual philosophical shift where aquatic management agencies now either consider the consequences of adding a new species prior to full-scale introduction or limit introductions to highly altered stream segments. Rainbow Trout Oncorhynchus mykiss is an emblematic non-native species regularly stocked to increase sport fishing opportunities. Understanding how Rainbow Trout introduction influences native species is limited by region-specific conditions, the spatial and temporal extent of investigation, and the limited mechanisms examined. Introduced Rainbow Trout at southern latitudes may seek critical thermal resources, along with other habitat characteristics, creating possible interspecific competition with native species. The goal of my thesis was to evaluate environmental conditions related to possible interactions between non-native Rainbow Trout and native warmwater fishes. My first objective determined habitat selection at two spatial scales by several native fishes to determine if the presence of Rainbow Trout altered their selection of important physicochemical resources. To evaluate the spatial extent of possible interactions between Rainbow Trout and native species, my second objective evaluated movement and dispersal patterns of Rainbow Trout following stocking. In addition, I quantified Rainbow Trout survival to assess persistence of this non-native fish over time. Collectively, my work provides key information on the spatial extent and possible interactions with native species over a 2-year period.