The marine living resources of the Southern Ocean have been harvested since 1790 when sealers first hunted fur seals for their pelts. By 1825, some populations of fur seal had been hunted close to extinction, and sealers begun hunting elephant seals and some species of penguins for their oil. Whaling in this area begun in 1904 and all seven species of whales found in the Southern Ocean were extensively exploited. Large-scale fishing did not begin until the late 1960s.

The Southern Ocean surrounds Antarctica and represents approximately 15 percent of the world's water area. It extends from the coast of the continent northwards to the Antarctic Convergence, a physically and biologically distinct frontal zone where the cold water of the Southern Ocean encounters, and flows under, the warmer and more saline sub-Antarctic water of the Atlantic, Indian and Pacific Oceans. The position of the Antarctic Convergence varies seasonally and geographically, but is generally located near 50^oS in the Atlantic and Indian sectors of the Southern Ocean and near 60^oS in the Pacific sector. The Southern Ocean (Figure B17.1) is divided into three statistical areas: Area 48 (Atlantic Antarctic) between 70^oW and 30^oE, Area 58 (Indian Ocean Antarctic) between 30^o and 150^oE, and Area 88 (Pacific Antarctic) between 150^oE and 70^oW. Each area is further divided into subareas and divisions.

The Southern Ocean is characterized by an eastward flowing Antarctic Circumpolar Current and a series of clockwise-rotating gyres that contribute to a westward flowing East Wind Drift along the Antarctic coast. The Southern Ocean has three distinct ecological zones: an ice-free zone to the north, an extensive seasonal pack-ice zone between approximately 55-60^o and 70-75^oS, and a permanent pack-ice zone adjacent to the continent. Antarctic krill, Euphausia superba, is abundant in the seasonal pack-ice zone where it provides the staple food for many species of whales, seals, birds and fish which inhabit the region.

Figure B17.1 The Southern Ocean (Area 48, 58 and 88)

Profile of catches

Close to 9.0 million tonnes of krill and fish were taken cumulatively from the Southern Ocean from 1969-1970, when records of commercial fishing began, to the end of 2001-2002 (the fishing year in the Southern Ocean is 1 July to 30 June of the following year). Most nominal catches (80.5 per cent) were taken in Area 48, that is Atlantic Antarctic between 1976-1977 and 1991-1992 (Figure B17.2 ), and the dominant species was krill (Figure B17.3). Next most important was the Indian Antarctic zone with 19.0 percent of the catch. But by 2002, these numbers had changed to 93 percent for the Atlantic zone, 6 percent for the Indian zone and nearly 1 percent for the Pacific zone. Important commercial species in the past included lanternfish (myctophids - principally Electrona carlsbergi); mackerel icefish (Champsocephalus gunnari), marbled rockcod (Notothenia rossii) and Patagonian rockcod (Patagonotothen guntheri), but these resources have been severely fished down. The major fishery is now for the valuable Patagonian toothfish (Dissostichus eleginoides and D. mawsonii) which in 2002 represented 63 percent of total catch by weight, excluding krill.

The commercial harvest of krill began in 1972, and annual catches from 1980 to 1992 exceeded 300 000t in most years, then decreased to 80 000-130 000t in recent years (Figure B17.3). At its peak of 528 200t in 1982, the fishery contributed approximately 13 percent of the global annual catches of crustaceans, and the subsequent lower catches (126 000t in 2002) reflect a decrease in landings, not overfishing. The fishery has operated mainly in Area 48, around the South Shetland Islands (Subarea 48.1) and South Orkney Islands (Subarea 48.2) in summer and adjacent to South Georgia (Subarea 48.3) in winter.

Figure B17.2 Annual nominal catches ('000t) by ISSCAAP species groups in the Southern Ocean (Areas 48, 58 and 88)

Figure B17.3 Annual nominal catches ('000t) of selected species in ISSCAAP groups 33, 34 & 46 Southern Ocean (Areas 48, 58, 88)

Reported catches in the fishery for marbled rockcod peaked at 399 700t in 1969-1970, and then declined precipitously to 101 560t in 1970-1971, and 2 740t in 1971-1972 as the stock was overfished and the fishery collapsed (Figure B17.3). Mid-water trawling for mackerel icefish started in the early 1970s, and this fishery was characterized by peaks of intense fishing (219 340t in 1978 and 162 600t in 1983) followed by periods of low catches and possible localized depletion from mid 1970s to late 1980s.

In recent years, fisheries in the Southern Ocean have targeted krill in Area 48, toothfish and icefish in Areas 48 and 58 (Figure B17.4).

Figure B17.4 Annual nominal catches ('000t) of selected species, Southern Ocean (Areas 48, 58 and 88)

Exploratory fishing has occurred for squid (Martialia hyadesi) and crab (mostly Paralomis spp.) in Area 48. The earlier exploratory fishing for Antarctic toothfish (Dissostichus mawsoni) in Area 88 has developed into a small, but commercial-scale, fishery.

The harvest of marine living resources in the Southern Ocean is managed under the International Whaling Commission (IWC) established in 1946, the Convention for the Conservation of Antarctic Seals ratified in 1978, and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) established in 1982 (see http://www.ccamlr.org for further information).

A moratorium on commercial whaling was introduced 1987, and extensive whale sanctuaries were established in the Indian Ocean in 1979 and Southern Ocean in 1994. Commercial whaling within these sanctuaries is prohibited. The recovery of whale stocks and the effectiveness of the moratorium and sanctuaries are being evaluated by the IWC. There are indications that some species of whale are recovering, but the low abundance of some of the largest species has made total numbers difficult to estimate from sightings data. Several hundred Minke whales out of an estimated 700 000 are currently taken annually in this area by Japan for research. Otherwise, recovery of the southern whale stocks proceeds slowly depending on species. Management of whales in the Antarctic, and elsewhere is the responsibility of the International Whaling Commission.

The commercial harvest of seals is regulated under the Convention for the Conservation of Antarctic Seals. Annual catch limits were set for crabeater seals (175 000 individuals), leopard seals (12 000 individuals) and Weddell seals (5 000 individuals), and the taking of fur seals, elephant seals and Ross seals for commercial purposes is prohibited. No commercial harvest has taken place in recent years.

In 1982, Parties to the Antarctic Treaty established CCAMLR under an international convention based on an ecosystem-wide approach to the conservation of marine living resources in the Southern Ocean, with conservation defined to include rational use. The conservation principles set down in the Convention require that exploited populations must not be allowed to fall below an abundance close to that which ensures their greatest net annual increase, depleted populations must be restored to such abundance, and the risks of changes to the marine ecosystem that are not potentially reversible over two or three decades must be minimized. Importantly, ecological relationships between harvested, dependent and related species must be maintained.

These stringent principles embody an ecosystem approach to the management of living resource and set the CCAMLR Convention apart from other regional marine resource management regimes. Management of fishing must not only aim to conserve the targeted species but take into account the impact of fishing on those animals that prey on, and compete with, the targeted species. In its broadest interpretation, the Convention requires that management action should take account of the impact of activities on all living organisms in the Antarctic ecosystem or sub-systems.

The status and management of the marine ecosystem of the Southern Ocean is reviewed annually by the twenty-three member countries of CCAMLR based on information gathered from the fisheries and fishery surveys, the Scheme of International Scientific Observation aboard fishing vessels, and CCAMLR's Ecosystem Monitoring Program. Fishery resources are reassessed, and the management regime is defined by Conservation Measures which regulate all existing, new and exploratory fisheries, and fishing for research purposes within the CCAMLR Convention Area (Areas 48, 58 and 88).

Complementary management measures are also in force in territorial waters adjacent to Prince Edward and Marion Islands (South Africa), and Crozet Islands and Kerguelen Islands (France) in Area 58. Of particular interest has been the recent creation of the world&'s largest fully protected marine reserve in the Australian sub-Antarctic. The 6.5 million-hectare Heard and McDonald Islands Marine Reserve would ensure that one of the globe's last pristine ecosystems remained intact. It surrounds the uninhabited Heard and McDonald group, and includes two large zones of the Southern Ocean. The Heard reserve is intended to protect the habitat and food sources of seals, penguins, and albatrosses, as well as marine life.

The bibliographic references are available through the hyperlink displayed in "Source of Information".