Methods for Fish Biology

Chapter 17: Behavior

David L. G. Noakes and Jeffrey R. Baylis


Behavior is one of the most conspicuous properties of animals. It is of considerable importance to ecologists in general and fishery biologists in particular. Feeding, spawning, migration, and reactions to collecting gear are obvious examples of fish behavior that have practical significance. Although behavior is readily observed, it is not necessarily easy to study. Careful planning of observation schedules and precise definitions of behavior units to be recorded are just the first elements to be addressed in a behavioral study.

In this chapter we provide a selective review of fish behavior likely to be of practical interest and application. We follow the approach of behavioral ecology, an active and rapidly progressing field (Krebs and Davies 1984) that incorporates studies in such major areas as foraging, predator-prey interactions, sex and mating behavior, and life history strategies.

A fish could engage in many different kinds of activities: searching for food, avoiding predators, searching for mates, schooling with other individuals, and responding to physical factors in the environment, for example. These activities may be mutually incompatible because the motor patterns involved cannot be performed simultaneously and the orientations of the responses differ. Consequently, the fish must have some means of determining which activity to carry out at a particular time, based upon the external and internal stimuli impinging upon it.

This process of selecting among activities is referred to as “decision making” (McFarland 1977, 1985). This is not meant to imply any cognitive awareness or consciousness on the part of the fish. Behavior, as any other phenotypic attribute, is the product of interacting forces of natural selection that produce an optimal compromise in the phenotype. We (and others) may discuss examples of behavior in terms that might imply that the fish are engaged in a particular behavioral activity in order to achieve some end or object. The words strategy and tactics are sometimes used in this context, but again not to imply consciousness or forethought. Strategy means a preprogrammed rule an animal follows; tactic means the methods (i.e., behavioral actions) used to implement the rule (the strategy) (Dawkins 1982).