Tristan da Cunha Group and Gough Island

Tristan da Cunha Group

The Tristan da Cunha Group is a scattered and extremely remote collection of islands in the South Atlantic (37 deg. S and 12 deg. W), almost midway between southern Africa and South America. There are five main islands: Tristan, Inaccessible, Nightingale, Middle and Stoltenhoff. Like Ascension and Saint Helena, the islands of the Tristan Group are the tops of submarine volcanoes marking the mid-Atlantic ridge. The top of Tristan (6760 feet or 2020 m above sealevel) is almost permenantly covered in cloud and in winter by snow. For some photos of the island and its inhabitants click here and here.

Discovered by the Portuguese navigator Tristao da Cunha in 1506, the islands were annexed by Great Britain in 1816, and made a dependency of the British colony of Saint Helena in 1938. There are some 320 inhabitants, most the decendants of shipwrecked sailors or immigrants from Saint Helena and Ireland. There are only seven family names on the island being Hagan, Rogers, Glass, Lavarello, Swain, Green and Repetto. The inhabitants were evacuated to Britain following a major volcanic eruption in 1961 but returned to the islands in 1963. There is a small crawfishing industry and famous sale of postage stamps. Tristan Islanders speak a distinct dialect of English that reflects their origins in Georgian England but is also laced with a few early Americanisms, again reflecting the influences of early sailors. The main settlement, named the Settlement of Edinburgh, lies on the NW side of the nearly circular island of Tristan.

How does one get to Tristan da Cunha? The answer is, with difficulty!! There is no air service, however the supply ship RMS St Helena calls there once a year. They carry a number passengers and make a detour around Inaccessible and Nightingale Islands before travelling to Gough Island, 200 miles to the south east before heading back to Cape Town, South Africa. Postal mail is delivered, more or less monthly, via Cape Town by the fishing vessels of the company licenced to fish in Tristan waters.

The Tristan da Cunha Group and Gough Island are extremely important for three albatross species, the endemic Tristan Albatross (recently split from Wandering Albatross), Atlantic Yellow-nosed Albatross (split from Indian Ocean Yellow-nosed Albatross), and Sooty Albatross. The vast majority of the world's Great Shearwaters breed within Tristan da Cunha (conservative estimates are of more than 5 million breeding pairs) or on Gough Island (between 600,000 and 3 million pairs). There is an annual harvest of shearwaters on Nightingale Island. In addition there is a good variety of breeding petrels and shaearwaters, including a number of endemic/near-endemic subspecies.

Breeding Seabirds

Rockhopper Penguin - subspecies moseleyi
Tristan Albatross probably 6000-7000 individuals

Atlantic Yellow-nosed Albatross (27,000-40,000 breeding pairs including Gough Is.)

Sooty Albatross
Kerguelen Petrel
Great-winged Petrel (subspecies macroptera)

Atlantic Petrel - few hundred pairs

Soft-plumaged Petrel (subspecies mollis)

Broad-billed Prion (subspecies vittata)

Spectacled Petrel
Grey Petrel
Great Shearwater
Little Shearwater (subspecies elegans)

Grey-backed Storm-petrel
White-faced Storm-petrel (nominate subspecies marina)

Black-bellied Storm-petrel (subspecies melanoleuca)

White-bellied Strom-petrel (subspecies leucogaster)

Common Diving Petrel (subspecies dacunhae)

Antarctic tern

Gough Island

Gough Island (40°21'S, 09°53'W) is small, mountainous and very remote volcanic island (14 km long and 7 km wide), located more than 2300 km SW of Cape Town, South Africa. The centre of the island is a plateau at 2000 feet with Edinburgh Peak, the island's highest point, rising above it to 2986 feet. On the western side, the plateau extends to cliffs of 1500 feet while on the eastern and northern sides, deep glens (steep-sided valleys) separated by narrow, serrated ridges cut far inland. The coastline is rugged, making landing difficult. The only human inhabitants are 6 or 7 personnel stationed at the South African Department of Environment Affairs and Tourism Weather Station on the SE side of the Island. Although first discovered by the Portuguese navigator Goncalo Alvarez in 1675 (he named the island Diego Alvarez), the island was 'rediscovered' in 1731 and renamed Gough after Captain Gough of The Richmond, a name popularized by visiting by British and American sealers and whalers. Sealers stayed on the island for considerable periods of time, subsisting on fish, seabirds, eggs, wild plants and cultivated potatoes (apparantly no longer present on the island). Scientists have visited the island periodically since 1811 and a permenant research base was first established by British scientists in 1955. Gough Island became a British territory in 1938 and is still formally under British rule.

Due to its unique fauna and flora, Gough was classified in 1995 as a World Heritage Site by UNESCO and as such there is presently no access for tourists and even crew members from passing yachts may not go ashore except in the case of an extreme emergency. Importantly, commercial fishing is subject to a licence being granted by the Tristan Administrator, and is only granted to one company that receives a predetermined quota. Anyone considering a scientific visit to the island must obtain permission from The Administrator of Tristan da Cunha (Address: The Residency, Tristan da Cunha, South Atlantic).

Lying on the edge of the "Roaring Forties", a seasonally oscillating wind-belt south of 40°S, the island experiences a cool-temperate oceanic climate. The mean temperature near sea level is 11.3°C with little seasonal variation. Extreme temperatures on the coast vary from -3°C to 25°C. The mean mean relative humidity of 80%. Snow occurs on the peaks between May and January, but rarely settles at lower altitudes. Not suprisingly, it rains throughout the year, with a mean annual precipitation of 3116 mm. The cloud base is typically between 300-500m, occasionally descending to sea level. Mean wind speed is 12 m/s-1, with a tendency for stronger winds in the winter. GIven its position in the southern Atlantic Ocean, the prevailing wind direction is generally westerly. Gales blow on 5% of summer days and 15% of winter days. Wind speed increases with altitude, and is exceptionally strong on exposed ridges.

Gough Island has been described as a strong contender for the title "most important seabird colony in the World" (Bourne, 1981). There are two endemic landbirds, the flightless Gough Moorhen (Gallinula comeri) with an estimated 2500 breeding pairs and the Gough Bunting (Rowettia goughensis) with an estimated 1000 breeding pairs.

Breeding Seabirds

Rockhopper Penguin - c. 48% world population
Wandering Albatross - up to 2000 breeding pairs

Sooty Albatross
Atlantic Yellow-nosed Albatross
Southern Giant Petrel100-150 pairs

Atlantic Petrel
Greater Shearwater - at least 3 million pairs
Little Shearwater
Antarctic tern
Subantarctic Skua

Marine Mammals

Southern Right Whale
Dusky Dolphin
Southern Elephant Seal - c. 100 individuals.

Sub-Antarctic Fur seal - 200,000 individuals and increasing.

Helpful Literature

Bester, M.N. (1990) Population trends of Subantarctic Fur Seals and Southern Elephant Seals at Gough Island. South African Journal of Antarctic Research 20: 9-12.

Bourne, W.R.P. (1981) Fur seals return to Gough Island. Oryx 16: p46-47.

Fraser, M.W., P.G. Ryan, B.P. Watkins. (1988) The seabirds of Inaccessible Island, South Atlantic Ocean. Cormorant 16: p7-33.

Richardson, J. (1984) Aspects of the ornithology of the Tristan da Cunha group and Gough Island. Cormorant 12: p122-201.

Ryan, P.G. (1991) The impact of the commercial lobster fishery on seabirds at the Tristan da Cunha Islands. Biological Conservation 57(3): p339-350.

Ryan, P.G., W.R.J. Dean, C.L. Moloney, B.P. Watkins and S.J. Milton. (1990) New information on seabirds at Inaccessible Island and other islands in the Tristan da Cunha group. Marine Ornithology 18: p43-54.

Ryan, P.G. and J. Cooper. (1991) Rockhopper penguins and other marine life threatened by driftnet fisheries at Tristan da Cunha. Oryx 25: p76-79.

Watkins and Furness (1986) Population status, breeding and conservation of the Gough Moorhen. Ostrich 57: p32-36.

Copyright © 2002 All rights reserved. Angus Wilson
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