Migration in Coral Reef Fishes: Ecological Significance and Orientation Mechanisms

Coral reef fishes are in general rather sedentary and territoriality and home range behavior patterns are highly developed. However, many species migrate, often relatively long distances compared to body size and often with spectacular precision. Migrations in reef fishes may be associated with: 1) life history—movements of planktonic larval stages to reefs or movements of juveniles from nursery areas to reefs; 2) seasons—precisely timed spawning aggregations drawing fishes to particular locations from wide areas of the reef; and 3) diel patterns—movements to and from feeding or resting areas associated with dawn and dusk. Of these migratory patterns the latter are the best known in coral reef fishes. Certain coral reef fishes seem ideal as a model system for studies of orientation mechanisms in fishes. Grunts (Haemulidae), for example, have relatively short, highly regular migrations that occur in all seasons. The fish are numerous, small, and able to withstand tagging and handling. Preliminary work on orientation mechanisms of grunt migrations has indicated the potential use of local landmarks, a distance sense and a sun compass. The persistence of migration routes in grunts and the preliminary demonstration of socially facilitated learning of routes by new recruits sets up the possibility of studies of the development of a “map” in grunts combining a variety of cues. The goal of studies in such a model system will be to develop testable hypotheses that may be applied to the orientation mechanisms guiding fish migrations in general