Coupled Physical-Biological Models for Predicting the Response of Salmon to Altered Flows and Habitat

Resource managers require predictions of how fish populations may respond to water and land use management actions,  creating a challenging problem for scientists because habitat changes can impact fish in myriad ways.  A variety of approaches are available for modeling fish responses, and at present, it appears that approaches must be tailored to the specific management problems.  California’s Central Valley poses especially severe challenges, where Chinook salmon populations persist in a highly regulated river system subject to competing demands for scarce water, and large-scale habitat and water management actions are under consideration.  We are developing a suite of tools to model how salmon respond to such actions, by linking hydrologic, hydraulic, water quality, habitat, and salmon models.  Salmon-focused models include statistically rigorous state-space population models; more complex population simulations that include life history responses; agent-based models of migratory behavior and survival; and individual-based models of growth and maturation based on dynamic energy budget theory. In this paper, we will provide an overview of these models, the challenges faced in their development, and insights into salmon biology gained from their application to specific resource management questions.