Subantarctic Islands, New Zealand

Published: March 13, 2009, 5:21 pm

Topics:

Biodiversity (main) Ecology (main) Geography (main)

Geographical Location

The Subantarctic Isles are a World Heritage Site group of islands including Snares Islands (48°02'S, 166°35'E), Bounty Islands (47°45'S, 179°03'E), Antipodes Islands (49°41'S, 178°48'E), Auckland Islands (50°45'S, 166°05'E), Campbell Islands (52°33'S, 169°09'E). The nominated World Heritage site includes the entire land and sea area comprising the five island groups and extending up to the 12 nautical mile (nm) territorial sea limit. The islands are distributed off the south and eastern coasts of New Zealand, the Antipodes Islands lying at a distance of 820 kilometers (km) from South Island.

Date and History of Establishment

Adams Island in the Auckland Islands was declared a Reserve for the Preservation of Fauna and Flora in 1910, the same designation being applied to the whole Auckland Islands group in 1934, to the Campbell Islands in 1953 and the remaining three island groups in 1961. In 1977, all five groups were reclassified as Nature Reserves under the Reserves Act 1977 (entering into force on 1 April 1978). All five island groups were subsequently accorded National Reserve Status. The Auckland Islands Marine Mammal Sanctuary came into force on 1 April 1993, under the Marine Mammals Protection Act 1978.

Area

The Southern Royal Albatross is a species native to the islands with no other known breeding grounds. Image was taken by Mila Zinkova. (Source: Wikimedia Commons)

The total land area is 76,458 hectares (ha), comprising Snares (341 ha), Bounty Islands (135 ha), Antipodes Islands (2,097 ha), Auckland Islands (62,560 ha) and Campbell Islands (11,331ha). The sea area is unquantified, but extends to the 12 nm limit.

Land Tenure

State owned. Land claims from two Maori groups have been laid before the Waitangi Tribunal. The World Heritage nomination does not affect these.

Altitude

Sea level to 705 meters (m), with the following maximum heights in the different island groups: Snares (152 m), Bounty Islands (88 m), Antipodes Islands (366 m), Auckland Islands (705 m) and Campbell Islands (569 m). Marine component extends 12 nm from each island group.

Physical Features

The islands lie on the shallow continental shelf off the south-eastern coast of New Zealand. The Snares and Bounty Island groups are formed of the basement granite and metamorphic rocks, while the three more southerly groups are basic volcanic structures dating from 25 million to less than 1 million years in age. Soils are mostly blanket peat, up to 8 m thick, but are absent from the exposed and low-lying Bounty Islands. Campbell and Auckland Islands show signs of extensive glaciation and have a number of harbors and deep inlets, while the Bounty Islands are a group of small and rocky islands with no safe anchorages.

Climate

The islands lie between the Antarctic and Sub-tropical Convergences in seas with summer temperatures ranging from 12° to 5.5°. They are strongly influenced by the prevailing westerly wind. They have a cool-temperate climate with at relatively low seasonal amplitude, the mean annual temperature ranging from 11° in the Snares to 6° at Campbell Island. Rainfall is high on most of the islands (1,200-1,500 millimeters (mm) a year) and there is frequent cloud cover. There are areas of oceanic upwelling to the west of Auckland and Campbell Islands.

Vegetation

A megaherb community growing on Campbell Island, one of the sub-antarctic islands of New Zealand. Taken by and originally posted to flikr by Twiddleblatt. (Source: Flickr Photos)

With the exception of the Bounty Islands which have no higher plants, the remaining islands, together with neighboring Macquarie Island, constitute a Centre of Plant Diversity, and have the richest flora of all of the Subantarctic islands. The Snares, Antipodes and two of the Auckland Islands (Adams and Disappointment) are remarkable in that their vegetation is essentially unmodified by humans or alien animals. The terrestrial flora comprises approximately 250 taxa, of which 35 are endemic to the region. The Auckland Islands alone have 233 vascular plants of which 196 are indigenous and six endemic. Thirty are classified as rare. The Auckland Islands have the southernmost forests in the region, dominated by Southern Rata Metrosideros umbellata and a flowering myrtle. Tree ferns reach their southern limit here. The Snares have extensive forests dominated by a tree daisy Olearia lyalli up to 5 m high. There are no comparable forests on the Campbell and Antipodes Islands, though woody shrubs are present. A particular feature of the islands are the megaherbs, including the endemic Stilbocarpa polaris and S. robusta (R), Anisotome acutifolia (E), and three species of Pleurophyllum which contribute to the rich and colorful flower gardens. Seaweed diversity is not as rich as on the mainland, but a new species of bull kelp Durvillaea has been identified from the Antipodes Islands.

Fauna

The fauna reflects the highly productive marine ecosystem which gives rise to a huge abundance and diversity of seabirds and marine mammals. The 120 recorded bird species include 40 seabirds, of which five breed nowhere else: Southern Royal Albatross Diomedea epomophora (LR), Gibson's Albatross D.exulans gibsoni, Antipodean Albatross D. exulans antipodensis, Campbell Mollymauk Diomedea melanophrys impavida (Thalassarche impavida) and White-capped Mollymauk D. cauta steadi (T. steadi). Ten of the world's 24 species of albatross breed in the islands. There are four breeding species of penguins, of which two, the Snares Crested Eudyptes robustus (VU) and Erect Crested E. sclateri (VU) Penguins are endemic; while Campbell, Auckland and Bounty Islands all have endemic species of shags, Leucocarbo campbelli, L. colensoi and L. ranfurlyi (all VU). Populations of seabirds on the Snares are particularly remarkable, with over 2.75 million pairs of the Sooty Shearwater Puffinus griseus. There is also a high degree of endemism among the land birds, including the rare Brown Teal Anas aucklandica (VU), one subspecies of which, the Campbell Island Teal A. a. nesiotis, is reduced to 25 pairs. Other endemic taxa of land birds include the Auckland Islands Rail Lewinia muelleri (VU), the Antipodes Parakeet Cyanoramphus unicolor (VU), snipe Coenocorypha aucklandica (LR) on Campbell, Snares, Antipodes and Auckland Islands, tomtits (Petroica macrocephala) on Snares and Auckland Island, and the Banded Dotterel Charadrius bicinctus exilis. The Auckland Island Merganser Mergus australis is believed to be extinct, having last been recorded in 1902. The islands are home to the rare Hooker's Sealion Phocarctos hookeri (VU) with an estimated population of 12,000-14,000 of which some 95% breed in the Auckland Islands, and the New Zealand Fur Seal Arctocephalus forsteri of which the largest breeding sites are in the Bounty Islands (20,000 in 1992). Southern Right Whales Eubalaena australis (LR) breed in the Campbell and Auckland Islands. There is one species of freshwater fish, the Koaro Galaxias brevipinnis, found in streams in the Campbell and Auckland Islands. The invertebrate fauna shows a high degree of endemism, with 36 of the 78 species of lepidoptera. All of the seven species of stonefly are endemic and there are endemic genera of wetas (Orthoptera). Insect faunas include: Auckland Islands (280 spp, 30% endemic), Campbell Islands (275 spp., 40% endemic), Antipodes (50 spp., 25% endemic). There are also a number of endemic snails and spiders. Marine diversity is not high, although the large Auckland Island Spider Crab Jacquinotia edwardsii is notable. The commonest inshore fish are nototheniids.

Cultural Heritage

The Kai Tahu iwi, the principal Maori tribe of South Island, is able to relate accounts of voyages to this region before European Settlement. The Bounty Islands were discovered by Europeans in 1788 and there was a rush of sealing expeditions in the early 19th Century but, by the 1830s, the seals were all but extinct. A party of Maori-Moriori from Chatham Island colonised Port Ross in Auckland Island in the mid-19th Century for a brief period, finally departing in 1856. Around the same time, a European whaling station was established in the same area, but it failed within three years. Rabbits, goats and pigs were released on several of the islands by sealers and to support shipwrecked sailors during the early 19th century. An era of farming started in the 1870s with an attempt at sheep farming at Port Ross, followed by Campbell Island in the 1890s. Sheep numbers at the latter peaked at 8500 in 1910 but was abandoned in 1931. Several coastwatcher stations were constructed at Auckland and Campbell Islands and manned during the Second World War. The final remaining sheep were eradicated from Campbell Island in 1992. Cattle were introduced to Enderby Island in 1895 and were finally eradicated in 1993.

Local Human Population

There is no permanent human population. A manned weather station existed on Campbell Island until it became automated in 1995

Visitors and Visitor Facilities

Tourism has developed since the late 1960s and visits by cruise ships have become regular since 1980, reaching about 10 ships a year recently. All visitors are required to have a permit and to be accompanied by a Department of Conservation representative who enforces the code of conduct. Visits are limited to a number of sites including Enderby Island, Auckland Island (Port Ross, Carnley Harbour) and Campbell Island. Boardwalks are provided at Port Ross (Erebus Cove) and Campbell Island to prevent trampling of sensitive vegetation. A maximum of 600 visitors a year are allowed to land at each site.

Scientific Research and Facilities

No permanent scientific research station but huts are available for visiting scientists on several of the islands. Research focuses on vegetation regeneration (following cattle and sheep eradication), visitor impact monitoring, marine monitoring, sea lions, seabird census and translocation of threatened bird species.

Conservation Value

Yellow-eyed penguins on Auckland Island. (Source: Wikimedia Commons)

The islands have a high and diverse population of seabirds, including several endemic species of penguin, albatross and shag. There are 14 endemic taxa of land birds, including one of the world's rarest ducks. The region, together with Macquarie Island, constitutes a Centre of Plant Diversity and is particularly rich among Subantarctic islands with a high level of endemism. The most southerly forests in the western Pacific and tree ferns are found here together with a spectacular flora of megaherbs. Several of the islands are unique in that their vegetation is essentially unmodified by introduced herbivores. The bulk of the world population of the rare Hooker's Sealion breeds on Auckland Island

The NZSAI taken together, are the most diverse and extensive of all subantarctic archipelagos. The five island groups of the NZSAI very markedly in size, geology, landforms and climate but their main distinction is that they are the most significant site for seabirds in all of Insulantarctica. They also stand out for their diversity and numbers of endemic landbirds, flora and for their low level of human disturbance.

The islands display immigration of species, diversifications and emergent endemism. Several evolutionary processes such as the loss of flight in birds and invertebrates offers particularly good opportunities for research into island ecology.

Conservation Management

A draft conservation management strategy was drawn up in 1995 and is scheduled for adoption in 1998. Its main features are restoration of terrestrial [[ecosystem]s], including pest eradication, survey monitoring and research, management of historic sites, and visitor impact control. One of the strengths of the nomination is the application of legal, administrative and management systems in place to safeguard the habitats and species of the NZSAI. Each of the five groups ahs been accorded the highest form of protection under New Zealand law- National Nature Reserves. Only one of the islands, however, has full protection of the surrounding marine area. Each of the individual islands has a management plan and a Conservation Management Strategy for all five is soon to be released.

Several of the NZSAI (Adams, Disappointment, Dent) remain in virtually pristine condition being rat and cat free and rarely visited by humans. The Antipodes have undergone minimal transformation although sealers were once active there. Pigs, cats, mice and rats, however do occur on the larger islands. Campbell's flora in particular was modified by an attempt at agriculture which failed in 1856. Sheep and cattle were subsequently introduced but the last few were irradicated in 1992. Rabbits and mice have been totally removed from Enderby and the degraded vegetation is steadily recovering. None of the NZSAI have been as adversely affected as by human activity as the Macquarie Island World Heritage site. Human impacts are confined to the effects of [[introduced] species] at Auckland and Campbell islands but their ongoing eradication is allowing the vegetation to recover and evolutionary processes to continue. It is the intention of the New Zealand authorities as spelled out in the Strategic Business Plan and the Conservation Management Strategy for the NZSAI to eventually remove all [[alien] species] from the islands. This is a commendable goal which will take some years but will provide a model for oceanic islands everywhere.

Management Constraints

Significant success has been achieved in eradicating [[alien] species], although they still occur on several of the islands, including pigs, cats and mice on Auckland Island, cats and Norway Rats on Campbell Island, and cats and mice on Masked Island. The cats, pigs and rats are believed to be impacting ground nesting birds and, in the case of pigs, impacting the vegetation. The flora of Campbell Island was severely modified by farming in the past and there are still a number of introduced plant species. The number of visitors poses a threat of further introductions.

Marine fishing activities are having an impact on pinnipeds and seabirds through incidental take. However this is monitored and the fishery (Fisheries and aquaculture) has been closed twice because the acceptable by-catch has been exceeded. Domestic commercial fishing in boats less than 43 m length is allowed within 12 nm of all the islands except Auckland. Longline fishing for Ling and Southern Bluefin Tuna is known to cause seabird mortality especially as the fishery around the Snares and Bounty Islands occurs during the austral summer breeding season of the albatrosses. There are plans for offshore oil exploration.

An additional problem in management of the marine area is the recent unexplained die off of sealions around the Auckland Islands. Sealion mortality has also been associated with the squid fishery in the area and some conservation groups have suggested closure under the Fisheries Act. However New Zealand's Department of Conservation has very limited powers to control commercial harvesting in waters surrounding the islands.

Staff

No resident staff but the Department of Conservation maintains staff responsible for these islands in Invercargill.

Budget

Unknown.

IUCN Management Category

• Auckland Islands National Nature Reserve Ia
• Campbell Islands National Nature Reserve Ia
• Antipodes Islands National Nature Reserve Ia
• Snares Islands National Nature Reserve Ia
• Bounty Islands National Nature Reserve Ia
• Auckland Islands Marine Mammal Sanctuary - Category unassigned
• Territorial seas at Campbell, Antipodes, Snares and Bounty Islands - Category unassigned
• Natural World Heritage Site - Criteria (i), (ii), (iii), (iv)

Further Reading

• Bibliography and further references are included in: Government of New Zealand (1997). Nomination of the New Zealand Subantarctic Islands by the Government of New Zealand for inclusion in the World Heritage List. Wellington, New Zealand. Includes:
• Department of Conservation (Southland Conservancy). 1995. Draft Conservation Management Strategy Subantarctic Islands.
• Department of Lands and Survey. 1987. Management Plan for the Auckland Islands Nature Reserve. Management Plans Series No. NR19.
• Department of Lands and Survey. 1984. Management Plan for The Snares Islands Nature Reserve. Management Plans Series No. NR9.
• Department of Lands and Survey. 1983. Management Plan for the Campbell Islands Nature Reserve. Management Plans Series No. NR13.
• Department of Lands and Survey. 1983. Antipodes Islands Management Plan.
• Department of Lands and Survey. 1983. Bounty Islands Management Plan.
• Molloy, J. and A. Davies. 1994. Setting priorities for the conservation of New Zealand's threatened plants and animals. Department of Conservation, Wellington. ISBN: 0478013779.
• Molloy, L.F. and P.R. Dingwall. 1990. World Heritage Values of New Zealand Islands, in Towns D.R., Daugherty C.H. and Atkinson I.A.E. (eds). Ecological restoration of New Zealand islands. Conservation Sciences Publication No. 2. Department of Conservation, Wellington. ISBN: 0478012047.
• Young, E.C. 1995. Conservation values, research and New Zealand's responsibilities for the Southern Ocean Islands and Antarctica. Pacific Conservation Biology, Vol. 2.

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the United Nations Environment Programme- World Conservation Monitoring Centre (ENUP-WCMC). Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the United Nations Environment Programme- World Conservation Monitoring Centre (ENUP-WCMC) should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

Citation

M, U. (2009). Subantarctic Islands, New Zealand. Retrieved from http://editors.eol.org/eoearth/wiki/Subantarctic_Islands,_New_Zealand