Diversity and biogeography of coastal fishes of the East Cape Region of New Zealand

C Roberts, A Stewart
A B S T R A C T A fish survey was carried out along 300 km of coast in the East Cape Region (ECR), North Island, between Whakatane (Bay of Plenty) and Gisborne (Poverty Bay) New Zealand during 1992-1999. Sampling, using mainly rotenone ichthyocide and handspear, was carried out at 0-21 m depth by teams of 4-7 divers who spent c. 200 hrs underwater collecting fish specimens and recorded identification and habitat data. A total of 148 fish species (114 genera; 65 families) were recorded in
more » ... recorded in inventory lists supported by voucher specimens. Of these, 107 shallow reef fish species were analysed to compare diversity and composition in four ECR subareas: East Coast, coastal Bay of Plenty (BOP), inshore BOP islands, and offshore BOP islands. No significant difference was found between the East Coast and the coastal BOP stations, and between the BOP inshore and offshore island stations; but there was a significant difference between all coastal stations (East Coast and BOP) and all island stations (inshore and offshore) using ANOVA and Tukey post hoc comparisons. Complementary results were obtained with Jaccard's pair-wise comparison between composition of reef fish faunas, which indicated that offshore BOP islands were the least similar to coastal BOP and the East Coast (46% species shared respectively); and the East Coast and coastal BOP were the most similar (79% species shared). Most reef fishes in the ECR (78%) were widespread New Zealand species; and there was a moderate northern component (20%) and small southern component (2%). There were progressive changes in composition moving from west to east and from offshore to inshore, with a reciprocal decrease in northern species and increase in widespread species, and a small increase in southern species. Northern species reached their limit of distribution variously at White Island, coastal BOP, East Cape, and East Coast; southern species reached their limits at East Cape. All these results provide strong support for a wide biogeographic transition throughout the ECR, and refute a narrow biogeographic boundary.