3. Chatham Rise
Map ID Number: 3
Location: A submarine extension of the New Zealand Plateau that extends eastward of the South Island for 1400km
Approximate area: 189,185km2
Description of area:
The Chatham Rise is a submerged platform of approximately 500-1000 m depth, located under the Subtropical Front, an intermixing area for subtropical and subantarctic waters.
Biological attributes:
The conditions associated with the Chatham Rise make it a diverse and productive habitat. The extensive area of the rise is characterised by high primary production. Of particular note is the large calanoid copepod (Neocalanus tonsus) which forms dense aggregations from late spring to early summer. Sei whales (Balaenoptera borealis), and broad-billed prions (Pachyptila vittata), are known to feed on this zooplankton species (Imber 1981). Other marine mammals known to forage on the Chatham Rise include sperm whales and beaked whales.
The rise is an important foraging area for seabirds from the Chatham Islands, southern New Zealand, and the subantarctic (e.g. the royal albatross). Particularly concentrated feeding spots are located around the Chatham Islands and close to the New Zealand mainland, but are also found on the slope areas. The Mernoo Bank, for example, is an important mixing area close to the mainland that is an important feeding ground for seabirds including Buller's mollymawk (Diomedea bulleri) and sooty shearwater (Puffinus griseus). The northern and southern slopes of the rise are subject to different hydrographic conditions, and therefore have different assemblages of foraging animals. The northern slope shows the effects of the subtropical current, while the southern slope shows the effects of the Subantarctic Front.
Criteria applied:
Species diversity; species richness (for seabirds and mammals as a result of highly productive oceanographic features). Focal point for foraging for a wide range of species that breed in subantarctic, New Zealand and the Chatham Islands.
Status and management:
The Chatham Rise is not managed specifically for seabirds or mammals which use the area for foraging, other than benefiting indirectly through the fisheries quota management system and observer programme. The fishing industry, conservation organisations, and government are working towards decreasing the level of non-fish mortality during fishing activities.
State of information:
Satellite-tracking of albatrosses is providing evidence of widespread foraging on the Chatham Rise. Information is inferred for cetaceans following reported sightings (Gaskin, 1968).
References and further reading:
Imber (1981, 1999), Nicholls et. al 2002), Waugh et al. (2002)