Population structure, abundance and reproductive parameters of bottlenose dolphins (Tursiops truncatus) in the Bay of Islands (Northland, New Zealand)

Abstract

Bottlenose dolphins (Tursiops truncatus) occupy a wide range of coastal and pelagic habitats throughout tropical and temperate waters worldwide. Around New Zealand, bottlenose dolphins inhabit three discontinuous regions in the north-eastern coast of the North Island, Marlborough Sound and Fiordland in the South Island. All these populations are subject to anthropogenic activities including dolphin-based tourism industry. Along the north-eastern coast of the North Island, the Bay of Islands presents a unique opportunity to study this population because of regular occurrence year-round and a history of long-term studies conducted in the region. This study examines the population structure and genetic diversity of the three New Zealand bottlenose dolphin populations to define their boundaries. Second, it focuses on the Bay of Islands subpopulation to investigate the dynamics of dolphin groups, pattern of habitat use, abundance and trends over time. Finally, it estimates reproductive parameters of female bottlenose dolphins to predict the long-term viability of the Bay of Islands subpopulation.