Goodwin, R. Andrew
Civil & Environmental Engineering, Cornell University; Environmental Laboratory, US Army Engineer Research & Development Center
James J. Anderson
School of Aquatic & Fishery Sciences, University of Washington, Columbia Basin Research
John M. Nestler
Director, Environmental Modeling and System-wide Assessment Center (CEERD-IT-Z), US Army Engineer Research & Development Center
Abstract
A theoretically- and computationally-robust mathematical approach for decoding movement patterns of individual fish responding to prevailing biotic and abiotic (physicochemical) stimuli is described. The modeling scheme, coupled EulerianLagrangian agent- and individual-based modeling (CEL Agent IBM) is intuitive and based on well-established principles in computer science, fluid and water quality dynamics, computational fluid dynamics (CFD) modeling, neuroscience, and game and foraging theories. In short, a CEL Agent IBM couples a 3-D Lagrangian particle-tracker supplemented with behavioral rules into a Eulerian CFD model. Mathematical structure of the behavioral rules is derived from an agent-based, event-driven foraging model. Stimuli are queried from information provided by a CFD or water quality model or other a priori field data. CEL Agent IBM coefficients are biologically tractable. Back-casting simulation analysis results in a mechanistic mathematical formulation of behavior amendable to forecast simulation. In this paper, we describe the theoretical concepts of a CEL Agent IBM used to decode observed 3-D movement and passage patterns of downstream migrating juvenile salmon (migrants) at Lower Granite Dam on the Snake River, Washington, USA. The prototype CEL Agent IBM (the Numerical Fish Surrogate) is presently being used by the US Army Corps of Engineers to quantitatively evaluate plausible response of migrants to virtual designs of alternative bypass systems at federal hydropower dams before they are built. CEL Agent IBMs are applicable to many aquatic systems and provide the theoretical and computational facility for improving existing individual-based modeling and water resource decision-support.