A SURVEY OF THE NEARSHORE REEF FISH FAUNA OF WESTERN AUSTRALIA'S WEST AND SOUTH COASTS - THE LEEUWIN PROVINCE

WA Museum Records and Supplements | Updated 9 years ago

Abstract: Twenty-three locations were surveycd along Western Australia's west and south coasts during thc period 1976-1993. This produced a total of 728 specics of reef fishes, of which 491 specics were tropical (67% of the total), 174 species warm-temperate (24%), and 36 species subtropical (5%) the remaining 27 species (4%) have uncertain distributions. Tropical fish numbers were highest in the Ningaloo Reef area at the northern end of the study area, the fauna reducing southwards to Rottnest Island, where it was nevertheless still prominent. The warm-temperate component was most numerous along the south and lower west coasts, its numbers reducing northwards to Shark Bay. Within the overlap zone of these two faunas, the subtropical fauna was at its strongest.

To examine the patterns of distribution, survey locations were divided into 12 regions and the fish fauna arranged into 13 range categories. Analysis of the data under these groupings produced numerous discrepancies in the diversity of the fauna. Thc most prominent one involved an "offshore" versus "inshore" effect to the tropical species. Evidence is presented showing that the Leeuwin Current is most likely responsible for this difference.

A "faunal signature" was identified for each survey region. This indicated that the endemic specics provide many of thc most commonly sighted fishes in the area between Shark Bay and Albany. These are gradually replaced to the north by wide-ranging tropical species and to thc east by warm-temperate species which range into other southern Australian states. On the basis of this uniquely Western Australian flavour, the name Leeuwin Province is suggested for the region encompassing Coral Bay and the Recherche Archipelago.