A Bioenergetic Evaluation of Changes in Habitat Quality for Salmonid Fishes: Calculating the Benefit from Stream Nutrient Enrichment in the Salmon River

In nutrient-limited aquatic systems, low-level nutrient supplementation has been employed to improve habitat quality for salmonid fishes. In this study, we use a bioenergetic foraging model to evaluate changes in habitat quality from experimental stream nutrient enrichment in four tributaries of the Salmon River, Idaho. We estimate habitat quality for four size classes of salmonid fishes by calculating net energy intake (NEI) rates as a measure of the available habitat that met growth requirements for a maintenance ration, as well as 50% and 80% of a maximum ration. Our study represents one of the first evaluations of changes in habitat quality for stream nutrient enhancement efforts. In this presentation we provide an assessment of energetic changes in habitat quality by comparing streams that received pasteurized salmon carcass analogs to those that did not, over a four month period. Bioenergetic models may offer an approach to evaluate large-scale changes in habitat quality for stream fishes. Such modeling efforts have the benefit of incorporating seasonal changes in habitat quality that account for changes in stream flow, temperature, and food availability. We hope to demonstrate the utility of bioenergetic models for evaluating changes in habitat quality that require an energetic estimate for issues like stream nutrient enrichment and climate change monitoring.