Assessment of predation risk by prey fishes

Successful predator defence depends on a prey fish’s ability to assess and respond appropriately to changes in predation risk. In their aquatic environment, prey fishes are almost continuously exposed to cues and stimuli that are associated with risk. As antipredator behaviours are energetically costly to perform (Endler, 1986, 1991) and divert attention away from other important activities such as foraging and courtship (e.g., Sih, 1980, 1988; Lima and Dill, 1990; Lima, 1998), they should be deployed only when absolutely necessary and remain sensitive to the level of threat posed (Helfman, 1989). The decision whether to initiate antipredator behaviours, therefore, requires accurate and reliable information about local predation threats (Kats and Dill, 1998). Fishes obtain this information through environmental cues that are detected and processed by their major sensory modalities: olfaction, vision and the lateral line system (Pitcher, 1986). However, these cues have very different properties, affecting the nature of information that can be obtained from them. The aim of this chapter is to examine the manner in which prey fishes detect and use different types of sensory information in order to assess their risk of predation.