Conserving Southern Ocean ecosystems: chequered past, difficult future
The Southern Ocean has suffered the ravages of over-exploitation since the late 18th century, including sealing, pelagic whaling, and overexploitation of fish species. The collapse of many fisheries throughout the world, particularly in the northern hemisphere, has meant that the relatively unexploited Southern Ocean is now seen as the last frontier for global fisheries.
The chequered history of the Antarctic marine ecosystem is similar to that of other large-scale marine ecosystems. What sets it apart is the political and decision-making regime covering Antarctic waters, developed over the past twenty years, which has given us the opportunity to determine what we need to manage Antarctic fisheries in an ecologically sustainable way. If successful, this could be a pattern for managing marine ecosystems elsewhere in the world.
Exploitation of Southern Ocean species is managed primarily under three different conventions: the International Convention for the Regulation of Whaling (1946), the Convention for the Conservation of Antarctic Seals (1978) and the Convention on the Conservation of Antarctic Marine Living Resources (1980) (CCAMLR). The latter two conventions are part of the Antarctic Treaty System.
The International Whaling Commission (IWC) agreed in 1982 to impose a moratorium on whaling beginning in the 1985–86 austral season, although despite opposition Japan has continued whaling under a special permit for scientific whaling. The work of the IWC's Scientific Committee – a pre-eminent forum for evaluating methods for assessing the status and yield of exploited populations and developing management procedures – has been a major precursor for approaches developed in CCAMLR.
The Antarctic Seals Convention, a 1978 instrument to protect seals and manage any commercial exploitation within the Antarctic Treaty area, south of 60° South, provides for a permissible catch between September and February in each year of crabeater, leopard and Weddell seals and forbids the killing or capture of Ross, southern elephant and fur seals. However, there has been no sealing at all since its inception.
CCAMLR, in force from 1982, was negotiated to ensure that the needs of the whole marine ecosystem were taken into account in managing, among others, the expanding krill fishery (Australian Antarctic Magazine 1:57). The convention was a major advance in the conservation and management of marine species in the Southern Ocean, not least because it extended beyond the Antarctic Treaty area to encompass the whole of the Southern Ocean south of the Antarctic Convergence (Antarctic Polar Front) – predominantly high seas but also including four undisputed national territories – Heard Island and McDonald Islands (Australia), Kerguelen and Crozet Islands (France), Prince Edward and Marion Islands (Republic of South Africa), and Bouvet Island (Norway).
The Commission established under CCAMLR (currently with 24 members and seven acceding states) has invited all countries involved in fishing for or trading in Southern Ocean species to attend its annual meetings. Namibia, as a port State, has recently become a member of the Commission and Vanuatu, a flag State, has become a contracting party.
With its broad mandate to address the conservation of the Antarctic marine ecosystem, CCAMLR also has the attributes of a regional fisheries management organisation. Its innovative ecosystem approach to managing fisheries places it at the vanguard of international instruments. This approach is governed by the three conservation principles in Article II of the Convention.
The first principle for target species is to ensure stocks are maintained close to levels that ensure greatest potential recruitment (birth and survival) of young to the harvested population. Methods derived from this approach, called 'maximum sustainable yield' – the catch expected to keep the stock at this level – were applied in early years but failed, and the approach is no longer applied to CCAMLR stock assessments. Nevertheless, current CCAMLR models rely on similar kinds of information, including knowledge of the dynamics of populations (birth and death rates), productivity of individuals including growth and reproduction, and the interaction between the fishery and the population (the ages or sizes of fish being exploited).
The second principle is conservation of the marine ecosystem, which fishing affects both directly – through by-catch of species including bottom-dwellers, finfish and seabirds – and indirectly through impact on food webs. In requiring the conservation of 'dependent and related species', the Convention implies that food webs should remain largely unaltered as a result of fishing. This makes research on the potential for competition between fisheries and Antarctic predators an important element of CCAMLR work.
Lastly, the principles of the Convention include rational use of marine living resources in the region, the need to allow the recovery of depleted species, such as seals and whales, and the need to avoid irreversible changes – changes that cannot be reversed within two to three decades.
All fisheries in the Convention area are subject to management controls (conservation measures). The main controls apply to total allowable catches, fishing methods, and seasons in each statistical area. Harvest controls are derived from the best scientific evidence available, based on assessments by the Scientific Committee's two working groups: fish stock assessment (developing management advice on toothfish, icefish and other fisheries except krill) and ecosystem monitoring and management (mainly concerned with assessment of krill fisheries and integration of data from the CCAMLR Ecosystem Monitoring Program).
CCAMLR now takes a precautionary approach to managing fisheries, which means that the absence of information does not prevent action being taken to ensure ecological sustainability is achieved. Under this approach, uncertainty is a factor in ensuring that risks to the environment are kept to a low level. In so doing, development of high seas fishing is prevented from escalating more rapidly than the ability to manage and mitigate against environmental impacts. Catch limits are set to keep stocks at or above target levels relative to an average level prior to fishing. Measures are also being established to mitigate the incidental mortality of seabirds in longline fisheries and minimise bycatch of non-target, finfish and other species.
The CCAMLR Ecosystem Monitoring Program (CEMP), initiated in 1986 to detect significant changes to the ecosystem resulting from fishing, was deliberately restricted to monitoring a few selected predators (feeding mainly on krill) in a few areas. Working out how the CEMP data will be utilised in formulation of advice is still being resolved.
A full management procedure for the krill fishery is to be developed over coming years (Australian Antarctic Magazine 2:47).
The Commission has established systems for making scientific observations of harvesting activities and inspecting licensed vessels' compliance with conservation measures, as well as measures to help ensure that CCAMLR members comply with conservation measures. CCAMLR's Standing Committee on Observation and Inspection recently established a catch documentation scheme to help restrict trade in Patagonian toothfish, Dissostichus eleginoides, to that caught in a manner that does not undermine CCAMLR (Australian Antarctic Magazine 1:56).
Measures to combat illegal, unregulated and unreported (IUU) fishing have been established under United Nations agreements. IUU fishing for Patagonian toothfish (see map on previous page) remains a serious problem for CCAMLR, and further control measures are being pursued.
Progress through CCAMLR's innovative advances in achieving ecologically sustainable harvesting of Southern Ocean species has been tarnished by the rapid rise and sustained activities of IUU fishing for toothfish species. The success of CCAMLR and other regional organisations managing high seas fisheries and the conservation of high seas biodiversity depends on management measures being successfully enforced at regional levels.
Manager, Southern Ocean Task Force