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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: 189,185km 2
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)
Stewart Island
Map ID number:
4
Location: Area includes
Southland coast, Foveaux
Strait, Stewart Island, Snares,
and outlying islands. (The
Snares are dealt with in the
subantarctic section – map
number 1)
Approximate area: 39,642km 2
Description of area:
Stewart Island lies on the shallow continental
shelf of the South Island, separated from the
mainland by Foveaux Strait, and surrounded
by many offshore islands and stacks. Although
there is a small human settlement the majority
is uninhabited and forested.
Biological attributes:
Stewart Island has a major proportion of
endemic and threatened species populations. It
also has a high level of species richness with 3
species of penguin (yellow-eyed (Megadyptes
antipodes), Fiordland (Eudyptes pachyrhynchus),
and blue (Eudyptula minor)), 8 species
of petrel, and 1 endemic shag (Stewart Island
shag), which breed on islands and coasts. The
New Zealand fur seal (Arctocephalus forsteri),
and several cetaceans including pilot
whales (Globicephala melas), beaked whales
(Mesoplodon spp.), southern right whales
(Eubalaena australis), and pygmy right
whales (Caperea marginata), are known from
the seas around Stewart Island. The Southland
coast is an important mainland site for the
endangered Hector’s dolphin (Cephalorynchus
hectori).
Criteria applied:
Species richness; species diversity; endemism;
cultural values; habitat complexity/diversity
(offered by large area under protection).
Status and management:
Much of the coast in this area is in pristine
condition due to remoteness, climate, a low
human population density and consequent
lack of human disturbance. Stewart Island
recently became a national park that includes
pest-free nature reserves (e.g. Codfish Island),
making it an important conservation area.
Much of this major natural heritage area is
accessible to the public. The area also has
high cultural significance for local Maori.
For example, the privately owned Muttonbird
Islands are important for customary harvest of
the sooty shearwater (Puffinus griseus).
State of information:
Good information for seabird breeding sites.
Foraging areas are less well known.
References and further reading:
Bejder and Dawson (2001), Department of
Conservation (1999c), DuFresne et al. (2001).
BIODIVERSITY – NEW ZEALAND’S MARINE ECOREGION ■ 23