Large-scale dispersal of the larvae of nearshore and pelagic fishes in the tropical oceanic waters of French Polynesia

Abstract

The larvae of tropical pelagic and reef fishes were sampled from October 1995 to August 1997 using a very large fry pelagic trawl at sites between 4 and 20° S and 134 and 154° W in the region of the Society, Tuamotu and Marquesas Archipelagos in French Polynesia. Sites were selected on the basis of longline catches of adult tuna (a predator of larval reef fishes) and acoustic surveys of micronekton to a depth of 600 m. A total of 3369 larvae were collected by 93 net tows. Most were late-stage larvae representing 29 taxa, of which 26 were predominantly reef fishes. Samples were dominated by acanthurids (43%), pleuronectiform larvae, ostraciids, fistularids, balistids, holocentrids, chaetodontids, mullids and carangids. Distance to reefs was the principal factor determining clustering patterns in classification and ordination analyses, and offshore samples (>150 km from reefs) were dominated by pelagic species, while collections nearer to reefs were dominated by coral reef species. There was a linear decline in richness of samples with increasing distance from reefs and an exponential decline in abundance, so that few reef fish larvae were collected >300 km from adult reef habitats. However, abundances of up to hundreds of reef fish larvae per hour of net tow were collected >100 km from the nearest reef. Our results show that relatively little connectivity is likely among reef systems separated by >300 km in French Polynesia, but substantial exchange of larvae within a restricted range of reef fish taxa might occur at smaller spatial scales. © Inter-Research 2006.