PHOTO-IDENTIFICATION OF HUMPBACK WHALES (MEGAPTERA NOVAEANGLIAE) IN NEW ZEALAND WATERS AND THEIR MIGRATORY CONNECTIONS TO BREEDING GROUNDS OF OCEANIA

摘要

Humpback whales pass along the coast of New Zealand as they migrate between summer feeding grounds in Antarctic waters and winter breeding grounds in the tropical waters of the South Pacific. The New Zealand humpback whales are probably part of the International Whaling Commission's (IWC) Antarctic management zone known as Area V, and are likely also a component of what the IWC terms "Breeding Stock E," whose boundaries extend from eastern Australia to Tonga. Discovery tags (stainless steel tags fired into the backs of whales and coded by the date and location) used between 1950 and I960 to track the movements of humpback whales established connections to Area V of Antarctica and showed whales migrating past New Zealand were linked to the migratorycorridors of Norfolk Island and Eastern Australia and the breeding grounds in Fiji (Chittleborough 1959, Dawbin 1964). It has long been assumed, but not shown to date, that a likely destination for these whales is Tonga due to the geographic proximity ofthese islands to New Zealand (Fig. 1). Recovery of the humpback whale population passing through New Zealand waters has been very slow and there are few reported sightings. Over a 30-yr period (1970-1999) a total of 157 sighting events were recorded, with the majority reported from the east coast of New Zealand (Gibbs and Childerhouse 2000). Almost half were from Kaikoura (east coast, South Island) and Cook Strait (between the North Island and South Island). The increase in commercial whale watching tours from Kaikoura may explain the higher recent sighting rate, as the majority of these reports were in the 1990s, just after the establishment of whale watching. With the Tory Channel (entrance to Cook Strait) having historic significance as the site ofone of the most successful whaling stations in New Zealand (Dawbin I960, Grady 1982), and with the apparent increase in humpback whale sightings in this area, it was decided to conduct surveys in the Tory Channel (Gibbs and Childerhouse 2004). Here we expand our knowledge of links between humpback whales in New Zealand waters and known breeding grounds in the Oceania (South Pacific) region (Garrigue et al. 2000).