Abstract: A method for determining the probable response of aquatic species to selected components of water flow fields, comprising the steps of obtaining data for identifying travel and quantitatively describing behavior of real fish constituting members of a selected aquatic species in a flow field, determining passive transport trajectories of the members of the aquatic species in the flow field to establish a basis from which to determine swim path selections, developing postulated behavioral responses of members of the aquatic species to at least one of hydraulic and acoustic stimuli, using statistical rules, and developing a computer utilizing the travel behavior data, the passive transport trajectories, and the postulated behavioral responses, to provide a virtual fish.