Biogeography of near-shore reef fishes in northern New Zealand

Species composition and richness of near-shore reef fish faunas around northern New Zealand were examined at different spatial scales. This comparison indicated a primary subdivision of faunas into three regional biogeographic groups: western North Island coast; north-eastern North Island coast and offshore islands; and Three Kings Islands. The western North Island reef fish fauna had low species richness, a predominance of widespread species over warm temperate species, and lacked subtropical and tropical species. North-eastern North Island and Three Kings faunas were richer, and incorporated mixes of widespread, warm temperate, subtropical, and rare tropical fish. Some frequent north-eastern North Island species were absent or rare in the Three Kings fauna; conversely, some species that were frequent at the Three Kings, including the restricted endemic Odax cyanoallix, were rare on the north-eastern North Island coast. The reef fish fauna of north-eastern Northland was further subdivided into three ecological-biogeographic subgroups, representing species assemblages of: headlands and islands strongly influenced by oceanic watermasses; open coasts predominantly influenced by coastal watermasses; and harbours and sheltered bays. Overall species richness and numbers of subtropical-tropical species were highest in the first subgroup, intermediate in the second, and lowest in the last-mentioned. The species assemblages of harbours and sheltered bays in north-eastern Northland had similar composition and richness to harbour and exposed open coast assemblages in western Northland.