Observations of live Gray's beaked whales (Mesoplodon grayi) in Mahurangi Harbour, North Island, New Zealand, with a summary of at-sea sightings

Abstract

A pair of free-swimming Gray's beaked whales, Mesoplodon grayi, an adult female and a calf, were observed in Mahurangi Harbour, near Warkworth, on the North Island of New Zealand, over 5 consecutive days in June 2001. Beaked whales (family Ziphiidae) are seldom seen at sea due to their oceanic distribution, deep diving ability, elusive behaviour, and possible low abundance. Gray's beaked whale is the most common beaked whale species to strand in New Zealand but observations of live animals in these waters are rare. Colour pattern and behaviour of these little known cetaceans are described. Although both animals appeared to be in good condition, the adult female had a series of deep corrugated scars behind her dorsal fin, likely the result of a ship strike. Other at-sea sightings of this species from International Whaling Commission (IWC)-International Decade of Cetacean Research (IDCR) minke whale assessment cruises and IWC-Southern Ocean Whale and Ecosystem Research (SOWER) circumpolar cruises are summarised. A cluster of sightings to the south-west of the Chatham Islands may indicate the existence of a "hotspot" for M. grayi in the New Zealand region.