Our understanding of habitat selection by reef fish larvae has changed dramatically in the last 10 years. Fish larvae have long been considered passive particles at the mercy of ocean currents, tides and weather events. For reef fishes, ecological evidence has shown that passive dispersal alone often cannot explain larval distributions, suggesting active behaviour by reef fish larvae. While behaviourally modified passive transport may be important, recent work demonstrates that some reef fish larvae have the capability to actively swim to settlement habitat. They can orientate to reefs from distances of at least 1 km and can swim at speeds of 13.5 cm s−1 for several days. The question then becomes, what are the cues that fish larvae use to orientate to reefs? Ambient reef sound has been shown to be attractive to reef fish larvae, and current research aims to understand better the nature and use of these acoustic cues. Other potential cues include chemoreception/olfaction, wave cues and visual location of reefs. A better understanding of active habitat selection and the underlying sensory and behavioural mechanisms will improve our knowledge of recruitment processes in reef fish ecology, and may have implications for active management of reef fish populations.

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Elasmobranch fishes have a well developed electrosense that is used for prey detection. Research into the nature of bioelectric cues emitted by prey has, however, been neglected, and consequently the spatial context in which the electrosense operates to detect and home in on prey is not completely understood. This study provided data on both ac and dc electric potentials produced by teleost, crustacean and bivalve prey, as well as measured the decay rates of electric field strength with distance. The electrosensitivity of two tropical elasmobranch species was calculated to be ~4 nV cm–1, from which it was calculated that these predators probably detect their prey at a range of ~0. 25 m.

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