Mw Holdgate

There is a contradiction in the title of this book. For most volumes about the Southern Ocean stress its circumpolar continuity. The West Wind Drift sweeps around the earth, south of the inhabited southern continents. The main hydro-logical features of the Pacific Ocean : the East Wind Drift at its southern margin, spilling into the Ross Gyre; the westerly current further north; the northward movement of cold, dense bottom water and of the less saline surface waters with their burden of floating ice; and the counter-balancing southward drift of intermediate water that wells up in the far south and enriches the upper layers with nutrients, are all equally characteristic of the Atlantic or Indian Oceans. The ice phenomena and biology of the Pacific Sector of the Southern Ocean likewise differ in detail rather than fundamentals from those in the other regions of the circumpolar oceanic continuum.

But the point of this book is to bring home to students of the Pacific how that great ocean is transformed in its southernmost part, south of the subtropical convergence and especially south of the Antarctic Convergence or frontal system which lies between 55°S and 60°S. The first chapters, on climate, hydrology and ice bring this out well and also make another important point: that the influence of the cold hub of the Southern Hemisphere, acting through the airs and waters it chills, extends to the climate and oceanic processes far to the north. The Antarctic is an important engine driving world climate. We are still ignorant of many of the inter-linkages between it and other regions—but it is pointless to study Antarctic climate as if it was a separate entity.

The Antarctic Sector of the Pacific is a model demonstrating Southern Ocean features more generally, and pointing up issues that now confront scientists and Governments alike. Much is known about the general patterns of marine circulation and the origins and drift of pack ice and ice bergs — in which the Pacific Sector is rich because so many have their source in the Ross Ice Shelf. But we remain ignorant of many crucial details. We likewise have a broad understanding of the make-up of the oceanic ecosystem — but the factors that determine the productivity of plant plankton in different parts of the region and in turn determine the production of krill and other components of the zooplankton remain only partly established. And while it is a fair generalization that almost anything can eat krill — baleen whales, seals, seabirds, and a number of fish — the trophic interactions between these organisms and others like squid, known to be abundant in the Southern Ocean, have still to be determined precisely. The Ross Sea was the subject of one of the first attempts at mathematical modelling of a part of the Antarctic Marine Ecosystem (Green Hammond, 1981) but the defects in this courageous effort only serve to underline the need for stronger biological research. This need has met with response through the BIOMASS (Biological Investigation of Marine Antarctic Species and Stocks) project, by SCOR and

SCAR, but there is much more to do. And we remain extremely ignorant of the life of the seabed over much of the Antarctic Sector of the Pacific.

The need for research is great because human impact on the Southern Ocean is now increasing again. A century and a half ago, the fur seals (and to a lesser extent the elephant seals) bore the brunt of human exploitation, following the discovery by Cook and others of their vast breeding populations on the Subantarctic Islands, including Macquarie and the New Zealand shelf islands. Because the seal stocks were an "open access" resource, unprotected by sovereign Governments, the sealing industry became a competitive free for all that took millions of skins from the circum-Antarctic zone in 1795-1830 and then collapsed because the resource had been virtually destroyed. Only now are fur seals again becoming numerous in their original haunts (and we cannot be certain that the pattern of species distribution has not been permanently changed). Likewise, shore-based and pelagic whaling gravely reduced the Antarctic stocks of great whales between 1900 and 1970, reducing the population of blue whales to under 5% of its initial size and cutting the sei and fin whales almost as drastically. Whales, too, were (and are) an open-access resource. Although the International Whaling Commission has done much to lead the industry towards responsible self-regulation, there is no certainty that its proposals will be respected by all nations. Meanwhile, the reduction in these whales has almost certainly allowed some other species to increase — including the small minke whale, the crabeater seal and the chinstrap penguin. It may also have left a "surplus" of krill for man to harvest, and a fishery has already been established and is now taking some 200,000 tonnes a year. The fin-fish resources of the Southern Ocean are also being exploited by fleets from far away — many from the Northern Hemisphere — and some have already been reduced by over-fishing.

It is clearly essential that these new fisheries are regulated so that they do not destroy the resources on which they depend, as the sealing and whaling industries did. But such regulation demands science. We need to know whether there really is a surplus of krill, and if so, how much. We need to know whether its harvest by fishing fleets will hamper the recovery of the whales, or endanger other components of the ecosystem. The risk is obvious because krill plays a central part in that ecosystem and makes up 50% of the animal plankton biomass. There is now a Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) to which all the nations engaged in Antarctic fishery belong, and this is unique in stressing the need to control exploitation so as to safeguard the ecosystem as a whole. But unless we understand that ecosystem, we shall continue to regulate by guess work.

This book highlights another area where our scientific knowledge is insufficient to allow definitive statements about human use of Antarctic resources. There are grounds for believing that there may be hydrocarbon minerals in the Ross Sea, and perhaps elsewhere in the region. The exploitation of such deposits would clearly be extremely difficult and expensive. With the world facing excess rather than shortage of oil, development is clearly highly improbable in the foreseeable future. But we cannot evaluate the probabilities without better geophysical knowledge. Nor can we predict the environmental impact of such developments with certainty unless we know far more about existing pollution levels, about those likely to arise from mineral development, or about the sensitivity of Antarctic marine organisms to the kinds of hydrocarbon likely to be released. The best guess may well be that the Southern Ocean is so vast that even a major oil spillage would have only a localized and transient effect — but we need to know more about the cumulative effects of low levels of pollutant over long periods. The new international agreement on the control of mineral exploration and exploitation demands environmental impact assessments, and it is by no means certain that scientists will be able to carry those out with the requisite certainty.

In the Antarctic, there is a long and good tradition of dialogue between scientists and Governments. The scientists of all the nations working in the region co-operate internationally through the Scientific Committee on Antarctic Research (SCAR) and the parallel Committee on Oceanic Research, SCOR. The Governments are concerned to develop the Antarctic Treaty System not only as a framework for peaceful co-operation in the land areas south of 60°S to which the Treaty applies, but as a series of measures to protect the environment of the wider Antarctic regions from damaging human impact. The CCAMLR Convention covers a broader geographical area than the Treaty and is a pioneering measure in the way in which it applies ecological concepts of resource management in advance of threat and with the aim of preventing damage. It is now being exposed to the test of practicality : is it a strong enough measure to control growing and competing fisheries on the high seas? Equally severe tests of practicality await the measures recently adopted to regulate mineral exploration and exploitation. It is one thing to agree on these well ahead of the commencement of mining activities so that an industry can plan in awareness of the standards it will have to meet and so prevent pollution from the outset. It is another to make them work rigorously in the exacting, and at times hazardous, conditions of the Antarctic. But it is right to try. It is also essential to recognize that these measures could founder unless they are underpinned by good science. This book shows that we know a good deal about the Antarctic Sector of the Pacific Ocean — but we will need to know more if we are to design our policies aright.

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