Stream Flow and Temperature Effects on Salmonid Population Dynamics: Integrated Modeling Across Scales and Data Types

A major challenge in ecology is developing robust models of population response to environmental change that work well across space. In the last decade, researchers have begun developing so-called integrated models that attempt to bridge the gap between specificity and generality by combining data sources into a single modeling framework. We present results from an integrated effort aimed at understanding how brook trout respond to variation in stream flow and temperature. Integrating data from presence/absence surveys, abundance surveys and mark-recapture studies, we identified that dynamics are dominated by egg/fry survival and that high flow in the autumn and low flow in the winter increase recruitment. Also, adult survival was positively correlated with spring temperature. Results from all three data sources generally agreed in magnitude and direction of environmental effects, strengthening confidence in inferences. These relationships between environmental variation and population dynamics generate response surfaces that can be used to forecast future population dynamics in response to environmental change.