WHAT THE PELAGIC STAGES OF CORAL-REEF FISHES ARE DOING OUT IN BLUE WATER - DAYTIME FIELD OBSERVATIONS OF LARVAL BEHAVIORAL CAPABILITIES

Late pelagic stages of coral reef fishes captured with light-traps wer e individually released during daylight by SCUBA divers in open water, 20-35 m deep, in the Great Barrier Reef Lagoon at three sites >1 km f rom the reefs of Lizard Island. Observations in situ on 111 individual s of 11 families, but primarily Apogonidae, Chaetodontidae and Pomacen tridae, constitute the first data of their kind. Most fish showed no o vert reaction to the divers. Some individuals of some taxa of three fa milies settled quickly to the bottom. Acceptable observations on swimm ing were made on 66 larvae. Individuals selected a wide range of depth s, but when grouped by family, mean depths chosen by individuals were: apogonids, 6 . 5 (+/- 1 . 5, 95% CI) m; pomacentrids, 7 . 7 (+/- 1 . 5) m; and chaetodontids, 9 . 3 (+/- 1 . 3) m. Rough estimates of speed of up to 30 cm s(-1) varied among taxa. Swimming directions of 59 of the 66 larvae were non-random. Mean directions differed among sites an d were offshore at all of them. Most larvae swam offshore regardless o f the side of the island where they were released. The late pelagic st ages of coral reef fishes are strong swimmers capable of active horizo ntal and vertical movement. They swim directionally, can apparently de tect reefs >1 km away, and orientate relative to those reefs. A taxono mic component is evident in many of these behaviours.