Tensions rise as Falklands fishing zone takes effect. Argentina, Britain try to avoid clash, but avoid concessions too

Britain's controversial fishing zone around the Falkland Islands took effect on Sunday, heralding the possibility of a fisheries ``war'' with Argentina in the South Atlantic. The possibility of all-out war is extremely remote, but incidents could occur in coming weeks that might lead to an international confrontation. Elections are expected in both countries this year. With the issue of sovereignty rights to the islands at stake, any hint of concessions by either side could prove politically damaging at home.

Quiet diplomatic efforts in the past two months aimed at renewing negotiations do not appear to have brought results. The United States in particular has been anxious to defuse the situation.

US foreign policy in Latin America was badly wounded following the 1982 Falklands (Malvinas) war because of American support for Britain, and Washington appears concerned that another conflict could inflict further damage. Earlier this month, President Reagan's envoy Philip Habib went from high-level meetings in Argentina to London to talk with Prime Minister Margaret Thatcher and Foreign Minister Sir Geoffrey Howe, but was received only by Foreign Office officials. A week ago, Gen. John Galvin, chief of the US Southern Command based in Panama, held talks with the Argentine defense minister and head of the joint chiefs of staff.

Argentina's argument with Britain over the islands dates back to before the Panama Canal was blasted through Central America, transforming the geopolitics of Latin America. Europe's use of the Cape Horn sea lane for trade with the Far East made the islands a vital coaling station and naval base. Whoever controlled them controlled the sea lane. When British troops landed and displaced the Argentine garrison in 1833, the islands passed to British control.

The rich southwest Atlantic fisheries were first exploited in the late 1970s, when Spanish and Argentine entrepreneurs set up joint ventures to lift catches of hake and squid from the near Antarctic waters. But after Argentina's defeat in the 1982 war, Britain created a 150-mile protection zone around the islands, and the Argentine coast guard could no longer patrol the waters.

``The Malvinas became the richest free fishing ground in the world,'' says a Spanish trawler owner. Soviet, Polish, Japanese, Spanish, and Taiwanese factory ships flocked there to reap the harvest.

The closure of the Falklands' waters to Argentina's infant deep-sea fishing industry and the incessant intrusion of foreign trawlers into Argentina's 200-mile exclusive economic zone spurred a vocal political campaign in Argentina, warning of depredation of the region's fish stocks. In 1986, the government responded, cracking down on illegal fishing in Argentine waters. This brought several trawler arrests.

In July, Argentina signed bilateral accords with the Soviet Union and Bulgaria that set limits on their catches in the region and gave implicit recognition to Argentine sovereignty over the islands. These deals prompted the British to impose a 150-mile Falkland Islands Conservation and Management Zone (FICZ), requiring foreign trawlers to have licenses as of Feb. 1.

Both sides now seem anxious to avoid confrontations. Possibilities of clashes exist on the edge of the zone, however. The British are expected to be cautious, trying an arrest only if an unlicensed trawler penetrates a long way into the zone. But many of the some 250 foreign trawlers with new licenses may find the FICZ uneconomic, says Julio Torres, an Argentine fisheries expert. Many of the valuable stocks extend well to the north into Argentina's 200-mile coastal zone.

The Argentine coast guard will watch carefully for trawlers straying into its zone, adds Mr. Torres. It may attempt arrests in the 50-mile ``ring'' outside the FICZ that Britain has claimed as part of a 200-mile economic zone around the Falklands. Some of this area overlaps with Argentina's coastal zone. Local trawler owners say the coast guard monitors the presence of every trawler in the South Atlantic, maintaining a daily update of their positions.

A seamen's strike has docked the Argentine deep-sea fleet. The Soviets and Bulgarians are not expected to embark on a major fishing effort until mid-February. Attention in the next few weeks will thus focus on the foreign fleets operating in the FICZ and what might happen should they stray into Argentine waters. If such trawlers requested British naval or air assistance, claiming they were in British waters, a clash could conceivably ensue.