1. Subantarctic Islands (and continental shelf areas to 500m depth)
Map ID Number: 1
Location: Island groupings to the south and southeast of terrestrial New Zealand including Snares, Bounty, Antipodes, Auckland, and Campbell islands
Approximate area: 104,113km 2
Description of area:
The five subantarctic island groups are scattered across the Campbell Plateau and other submerged shelves of the southern New Zealand continental region. The plateau is a major feature that sits just north of the Subantarctic Front, at the northern boundary of the Antarctic Circumpolar Current that circles the Southern Hemisphere and connects all the large ocean basins. Despite there being plenty of phytoplankton nutrients, such as nitrates, the region has relatively low levels of phytoplankton biomass and primary production (Bradford-Grieve et al. 2003, Peat 2003).
Biological attributes:
The subantarctic islands are highly pristine and lack disturbance. Each island has a unique faunal assemblage because of their wide geographic spread and diverse and productive marine environment. Some islands have no introduced pests (e.g. The Snares, and Adams Island in the Auckland Islands group), and on others the pest mammals have been removed (e.g. from Enderby Island and Campbell Island). All islands provide excellent seabird nesting and marine mammal breeding locations that are close to major feeding areas. The Auckland and Campbell islands are a winter breeding ground for a remnant population of southern right whales (Eubalaena australis). The continental shelf is a productive area for inshore and shelf feeders, such as the yellow-eyed penguin (Megadyptes antipodes) and New Zealand sea lion (Phocarctos hookeri).
The islands are also good locations for albatrosses to access remote productive feeding areas in the subantartic. Forty seabird species (11% of the world total) breed in the New Zealand subantarctic and over 120 species have been observed at the islands or in the surrounding oceans. These include 10 (42%) of the world's 24 albatross species that breed in the New Zealand subantarctic (5 are endemic to the region), making the area a centre of biological diversity for albatrosses. Furthermore, 21 (30%) of the world's petrels, shearwaters, fulmars, and prions are observed in the subantarctic islands. Four penguin species breed (Snares crested (Eudyptes robust-us) and erect-crested (Eudyptes sclateri) are endemic) and there are three endemic shag species (Campbell Island, Auckland Island,and Bounty Island shags). Table 1 indicates the number of seabird and marine mammal species that breed on each of the subantarctic islands.
Table 1. Seabirds and marine mammals that breed on the subantarctic islands:
| |
Antipodes Islands | Auckland Islands | Bounty Islands | Campbell Island | Snares Islands |
|---|---|---|---|---|---|
| Albatross | 4 | 4 | 1 | 6 | 2 |
| Flightless duck | 0 | 1 | 0 | 1 | 0 |
| Penguin | 2 | 2 | 1 | 3 | 1 |
| Petrel | 12 | 10 | 2 | 9 | 8 |
| Tern/gull | 3 | 4 | 1 | 4 | 2 |
| Seal | 2 | 2 | 1 | 3 | 0 |
| Whale | 0 | 1 | 0 | 1 | 0 |
Criteria applied:
Species richness; endemism; unusual degree/proportion of biomass (e.g. millions of seabirds occupy the Snares).
Status and management:
All islands are nature reserves and collectively are a World Heritage Site, and the Auckland Islands are surrounded by a marine mammal sanctuary and marine reserve. Several endemic species are considered to face a high threat of extinction under the IUCN and/or Department of Conservation threat classification schemes. For example, two penguin species (yellow-eyed penguin and erect-crested penguin) are currently listed as endangered under the IUCN classification. 4 Most albatross are classified as at least “vulnerable” because of large population declines and small breeding areas. More widespread species have also shown greater than 90% declines in population in the New Zealand region, such as the rockhopper penguin (Eudyptes chrysocome), grey-headed albatross (Thalassarche chrysotoma), and southern elephant seal (Mirounga leonine).
State of information:
The breeding information for most species of birds and mammals in the subantarctic region is very good. Population assessments are, however, of variable quality and reliability, depending upon the species. Knowledge of species relationships is good. Information on foraging is limited, therefore niche separations are not as well understood. There is detailed information available for some species, such as the New Zealand sea lion. Extensive information is available from satellite telemetry of Buller’s albatross (Thalassarche bulleri), Gibson’s albatross (Diomedea gibsoni), and Antipodean albatross (Diomedea anipodensis) and to a lesser extent some other albatross species.
References and further reading:
Childerhouse and Gales (1998, 2001), Childerhouse et al. (2001), Cunningham and Moors (1994), Department of Conservation (1997,1999a), Gales (1998), Gales and Fletcher (1999), Hitchmough (2002), IUCN (2002), Miskelly et al. (2001), Peat (2003), Parliamentary Commissioner for the Environment (1999), Robertson and Nunn (1998), Stahl and Sagar (2000), Taylor and Taylor (1989), Tickell (2000), Waugh et al. (1999).