Co-evolution of movement behaviours by tropical pelagic predatory fishes in response to prey environment: a simulation model

Predatory fishes, such as tunas, billfishes, and sharks, coexist in pelagic regions of the tropical oceans. In situ experiments have revealed horizontal and vertical movement patterns for different pelagic species, but the influence of the biotic environment on movement behaviour has not been studied. In this paper, we propose a simple model in which the movement behaviour of these fishes is driven entirely by the biotic environment, without implementing physiological constraints. We explore this concept via computer simulations based on the Latent Energy Environments model [Menczer, F., Belew, R.K., 1996a. From complex environments to complex behaviors. Adapt. Behav. 4(3/4), 317–63]. In our model, multiple behaviours for artificial fishes evolve in a three-dimensional environment where spatial and temporal distributions of prey are patterned after hydroacoustic data taken during ultrasonic telemetry experiments on tunas in the open ocean in French Polynesia. Interactions among individuals are modeled through their shared prey resources. Movement patterns of the adapted individuals are analyzed to: (i) compare artificial individuals with real fishes (three species of tuna, three species of billfishes, and one species of shark) observed by ultrasonic telemetry; and (ii) examine how the artificial fishes exploit their environment. Most of the individuals evolved vertical patterns virtually identical to those exhibited by fishes in the wild. The agreement between our simple model and the ethological data validates the use of computational models for studies of the characteristics of multiple species inhabiting a common ecosystem. © 2000 Elsevier Science B.V. All rights reserved.