Delegates from 13 nations meet in Washington today to discuss whether to open the waters around Antarctica, the Earth's most pristine continent, to oil exploration and extensive commercial fishing.

For 20 years, "The Antarctic Club," which includes the United States, Japan and the Soviet Union, has governed that desolate, ice-bound wilderness as a haven for scientific research, free of arms and industry despite competing territorial claims of several nations.

But the harmony that has prevailed since the 1959 Antarctic Treaty is under serious strain. Concern is mounting that a rush to develop the continent's potentially rich resources will damage irreversibly the world's most untouched ecosystem. And, if states disagree over fishing and oil-drilling rights critics fear the treaty could collapse, leaving Antarctica open to superpower rivalry.

The 13 treaty members include seven nations with partly overlapping land claims: Argentina, Australia, Chile, France, New Zealand, Norway and Britain. Six other parties -- the United States, the Soviet Union, Japan, South Africa, Belgium and Poland -- do not recognize the territorial claims and make none themselves. Until now, the treaty has rested on a delicate arrangement in which the members govern by consensus and agree to disagree on claims.

In April, 20 U.S. environmental groups wrote President Carter, asking him to propose that Antarctica become a "World Preserve," closed to mineral exploitation.

"Oil exploration would be a disaster," says James N. Barnes of the Center for Law and Social Policy, a member of the official U.S. delegation. Such exploration "would damage the potential for harvesting Antarctica's food resources (which) can play an important role in providing rotein to a hungry world."

In the three-week negotiations that begin today, oil and fish are inextricably entwined.

For two years, the parties have been wrangling over a draft agreement to control the exploitation of marine resources, especially protein-rich krill. Krill, three-inch-long shrimp-like creatures, swarm through Antarctica waters in immense pink masses.

As more nations restrict fishing within their 200-mile coastal zones, the rich waters of the Southern Ocean offer the tempting possibility of increasing the world's fish catch dramatically. The Soviet Union, Japan Poland, South Korea, Taiwan, West Germany and East Germany already are harvesting krill and other fish.

The draft agreement has been held up by French concerns over controlling waters around their islands, Kerguelen and Crozet. Delegation members, however, predict it will be ready for signing within six months.

U.S. officials call the new treaty "innovative" in its dedication to conservation of a whole ecosystem, not just of individual species. But in a July article in Foreign Policy magazine, two experts from the International Institute for Environment and Development say a provision allowing any party to the treaty to veto a conservation rule "virtually guarantees that no restrictive measures will be implemented . . . It will be hard to prevent overfishing."

Overfishing krill, scientists say, could have "catastrophic" ecological effects, because krill form the basis of the Antarctic food chain. Krill are the major food supply of five species of whale, three of seal, 20 of fish, three of squid and many species of bird.

Furthermore, in tiptoeing around the emotional issue of national sovereignty, the fisheries agreement opens the way to future conflict, critics contend. Several nations reserve 200-mile econimic zones in waters around their Antarctic claims. If overfishing occurs, they could insist on the right to regulate the catch unilaterally.

R. Tucker Scully, a State Department Antarctica expert, calls the agreement "a very delicately balanced structure of political issues . . . States would think long andhard before they throw it away in the name of pressing claims."

But if international law generally recognizes fish as free-for-all renewable resource, offshore oil -- a dwindling commodity -- is traditionally the property of a coastal nation.

"The oil belongs to Australia" within 200 miles of its claim, asserted Ambassador Keith Brennan, head of the Australian delegation, in an interview late last week. Australia's claim includes 30 percent of Antarctica's coast.

However, for the time being, U.S. oil companies may be the only ones with the technology to explore the Antarctic seas, and they are pushing the United States to advocate exploration on a first-come first-served basis.

The United States "should have the opportunity to share in the benefits of mineral exploration in a nondiscriminatory fashion," says John Negroponte, head of U.S. delegation.

Delegates predict the sovereignty issue will be much more difficult to solve in the case of minerals than of fish. Barnes, of the Center for Law andSocial Policy, fears that if oil exploration is pursued, "The claims issue could blow up and the Antarctic Treaty could fall apart, leaving the U.S. and Russia vying for control of the continent."

There are important defense reasons for declaring a world preserve and safeguarding the world's only example of true arms control, he said.

Environmentalists also fear oil spills in Antarctica could affect the world's climate, because the continent is linked by ocean currents and atmospheric circulation to the rest of the Earth.

Spills would be inevitable, they say, given the area's 200-mile-an-hour winds, rapidly moving underwater icebergs and stormy seas. Oil degrades very slowly incold water, thus potentially causing more harm to wildlife than spills in temperate climates.

"Antarctic ecosystems appear to be so fragile that any exploitation activities would produce adverse effects, many of which would be severe and virtually irreversible," wrote Russell Train of the World Wildlife Fund, Russell Peterson of the National Audubon Society and other and other conservationists in their letter to Carter.

Nontheless, at a time when oil shortages threaten the economic stability of Western nations, the prospect of major new discoveries may be irresistible.

The U.S. Geological Survey has estimated, based on sketchy information, that Antarctica's continental shelf could contain as much as 45 million barrels of oil -- one and a half times current U.S. reserves. In 1972 and 1973, a research ship, the Glomar Challenger, drilled four holes in the Ross Sea and found ethane and methane, two gases associated with oil.

At the moment, the Antarctic partners have agreed to a policy of voluntary restraint, discouraging any exploratory drilling until more is known about the environmental consequences.

Meanwhile, in the negotiations this month, they will determine what kinds of studies are needed and begin talking about a political and legal system to govern exploration when it takes place.

The United States, the Soviet Union, West Germany and Norway already have conducted seismic surveys, the first step in any mineral research.Texas Geophysical Co. of Houston claims commitments from nine oil companies in an effort to set up an Antarctic consortium.

Three oil companies are represented on the State Department's Antarctic advisory committee: Atlantic-Richfield, Exxon and Gulf. In December Gulf submitted a proposal for a joint research project with the National Science Foundation on the geology and resources of the Antarctic continental shelf.

If oil eventually is found off thegreat white continent, international lawyers are predicting that Third World countries will demand a share of the wealth.

"It is difficult to expect developing countries which are not participants to lie back and accept that a self-appointed group of states should be running the show," says Alvaro de Soto, a Peruvian diplomat who represents Third World nations in Law of the Sea negotiations.

But treaty parties are in no hurry to widen participation. Australia's Brennan says it is too soon to talk about sharing royalties with developing nations, adding that the Organization of Petroleum Exporting Countries "does not share the proceeds of their oil. There are few international precedents for it and we have no intention of starting one."