The steamy, silent Pantanal, a vast swampland at the heart of South America, should be a paradise for the 5,000 species of wildlife, fish and plants here -- and for the few farming communities so distant from the centers of organized crime.

Yet the Pantanal forms Brazil's unguarded western border with both Paraguay and Bolivia, and, stimulated by chronic socioeconomic problems, this is enough to guarantee the region a lively traffic in drugs, weapons, stolen cars and, above all, the skins of alligators illegally hunted at the rate of 1 million a year.

Teams of poachers equipped with high-speed launches, light aircraft, radio cover and automatic weapons with nightsights are terrorizing the world's largest inland swamp.

In pursuit of their prey, a smaller, darker cousin of the Florida alligator, they frequently engage in violent clashes with authorities in the states of Mato Grosso and Mato Grosso do Sul, on the southern border of the Amazon region.

Poachers and their bosses in Paraguay and Bolivia continue killing Brazil's wildlife with impunity, despite periodic police raids. In March, a nationwide operation against international drug traffickers also reached the edge of the Pantanal, coinciding with the crackdown on the U.S.-Mexico border and the killing of U.S. narcotics agent Enrique Camarena Salazar.

Links between drug and alligator hide peddlers have not yet been thoroughly proven, but the head of Brasilia's drug squad, Maghalhaes Pinto, said in a telephone interview that there was "no doubt" new police raids would be carried out shortly, as the Pantanal was a major conduit of cocaine and base chemicals for clandestine labs.

In 1983, the armed forces carried out a full-scale anti-insurgent operation against the Pantanal's wildlife poachers, using helicopters and gunboats. But the difficult terrain and uncooperative population limited its effectiveness, and many dealers were tipped off in advance.

Once the skins of the Brazilian alligator, or cayman, have been airlifted across the frontier by bush pilots, they are legally exported to the United States and Europe from Bolivia, which is not a signatory to conservation treaties.

The illicit trade flourishes because cattle raising -- the only other significant economic activity in an area larger than Portugal and Switzerland combined -- has been decimated by government neglect and climate. Crime sustains the economy in a region whose population is 200,000.

"This place used to be white with cattle, but then the floods came in 1974 and we lost 2,000 head. We're now a forgotten region," said Luyl Goncalves de Castro, whose 40,000 acre ranch on the banks of the Paraguay River now has 100 steers and a battered airplane.

"There's no more work on the farms, so the men went to the city and they're mostly hunting alligators," Goncalves said. "This alligator business started when the economy went bad." A study by the University of Mato Grosso found that 90 percent of the region's unemployed survive by predatory hunting and fishing.

Cattle raising in the Pantanal depends on natural pastures that, like the banks of the Nile, surface during the period of low water. But for a decade the region has been subject to a flood cycle when the waters of the Paraguay cover the pastures and cattle cannot feed.

"In 1974 the region had 3.5 million head of cattle -- today we have less than a million. For a decade, the government simply ignored the Pantanal's tragedy," said Francisco de Barros por Deus, president of Corumba's association of farmers. The only significant federal aid project, the Transpantanal Highway, was washed out with the floods. Until a highway was built to Mato Grosso's capital, Cuiaba, a decade ago, Buenos Aires was easier to reach -- by river -- than Rio de Janeiro, and the region was cut off from modern Brazil. According to Por Deus, the region is now returning to a period of low water, and farming will pick up. But in social terms, the damage done by the exodus of workers from idle cattle ranches is considerable -- and the victims are wild animals.

"Rural workers went to work as coureiros or alligator poachers, but their problem is above all socioeconomic. Nowhere in the world has such a problem ever been solved by punitive police expeditions," said Por Deus.

Farmers were discouraged by the poor results of the military's September 1983 "Operation Pantanal," which succeeded in detaining no more than 150 of the estimated 3,000 city-based coureiros and impounding 15 light planes, which were soon released. After the operation ended with the deaths of about 22 poachers, the alligator mafia quickly regrouped.

Farmers charge that officials from the Mato Grosso state environmental protection agency engaged in subsequent operations repeatedly have raided farms to close airstrips, seize personal defense weapons and intimidate workers -- while known poachers operate unimpeded from the border city of Corumba.

"We know there are many instances of excesses by the authorities and that these people aren't able to organize themselves because they're very afraid," said Corumba's bishop, Vitorio Pavanello.

A boat trip into the Pantanal near Corumba shows the difficulties under which the authorities operate. By day, the teams of coureiros sleep, or salt and skin the hundreds of alligators they shoot in a night.

The coureiros, generally Brazilians contracted at about $5 per hide, load skins aboard light planes, whose pilots in turn will sell them across the border for $15 each. Some teams have been detained with 1,000 skins. Hunters also do not hesitate to bag the spotted Jaguar, an animal near extinction.

If the primieval, mosquito-infested landscape of dense swamp vegetation and interconnecting channels aids the poachers, frightened farmworkers do little to help authorities. Over the airwaves from Corumba's CB raido come coded warnings to coureiros of police movements, and a handful of larger landowners is known to profit from the skin trade.

"We want an initiative from the government to stop this aggression against the environment and private property," said Por Deus, explaining that armed poachers also steal cattle and invade farms.

The fact that authorities can make little headway against big traffickers is proof enough for some of crime's powerful connections in the Pantanal. "The big traffickers are never caught, and the level of policing shows that it's tolerated -- it's only the small operators who get picked up," said Bishop Pavanello.

The Pantanal's plight is now attracting serious government attention. In November 1984, agriculture minister Nestor Jost opened an important research center in Corumba to coordinate study and measures to stimulate the economy.

The national agriculture research institute also is supporting research into commercial farming farming of alligators, similar to that in Florida.

"We have to introduce more females to compensate for the indiscriminate killing, but the alligator isn't yet threatened by hunting," said Francisco Brayer, director of a project that by 1986 is to set up commercial farms to market alligator meat and hides. "We want to develop the Pantanal's resources without destroying it," he said.

Brayer says that as the dominant predator, the reptile helps preserve ecological balance. Its decline has increased river populations of deadly piranha.

The research institute also plans to farm the capybara, a 160-pound rodent whose pelt was once valued, but because of a population explosion now competes with cattle for pasture. Capybara meat could be sold as pet food to developed countries, experts say.

The Pantanal's farmers are enthusiastic about the institute's assistance, which has increased beef yields dramatically and now offers them untraditional farming alternatives that will help end the ravages of illegal hunters.

"If we can raise beef, why not alligators or capybara?" asks Por Deus.