Several giant tortoises and 30 scientists have been held hostage in the Galapagos Islands by fishermen who are demanding more rights to fish for sharks.
The scientists are being confined in the Charles Darwin research station, on the island of Santa Cruz, by the fishermen, who are refusing to allow food or supplies to reach them, threatening the welfare of the scientists and the tortoises.
Inside the compound are 33 people and an unknown number of rare tortoises.
The Galapagos, a cluster of islands 966km off the coast of Ecuador, in South America, are home to exotic sea lions, iguanas, tortoises and birds, and are famous for unique species that inspired Darwin to develop his theories about the origin of species.
Giant tortoises on different islands developed characteristics to cope with local conditions and are all now extremely rare.
The dispute with the fishermen is not about tortoises but about fishing methods and how many sharks they can catch.
Conservationists fear that the long-line shark fishery will kill albatrosses, sea lions and turtles.
The fishermen also want to supplement their incomes by allowing access to the islands for cruise ships, claiming this will bolster the already booming tourist trade.
Fishing and tourists are carefully controlled on the island because of the damage to the wildlife they cause.
The problem has escalated because the population of the islands has continuously increased, despite efforts to control it.
This means that the quotas for catches are shared ever more thinly.
The fishermen's protest has been peaceful for the most part but four years ago, when they were demanding increased quotas for lobsters, bands of them wrecked research facilities, harassed tourist groups and threatened the lives of national park staff.
On that occasion the government of Ecuador, which controls the islands, sent in troops, who struggled to contain the problem and eventually capitulated.
The government raised the lobster limit to placate the fishermen, leaving conservationists fearing that it was only a matter of time before it happened again.
John McCosker, the chairman of aquatic biology at the California Academy of Sciences, who was in the islands during the last dispute, said that the concessions were "institutionalizing blackmail."
He said: "It's tragic, the short-term gain of a few fishermen versus the long-term survival of the Galapagos.
"They are killing the golden goose," he said.
This time campaigners are urging the government to stick with the bans on shark fishing and cruise ships to keep the local environment healthy.
Much of the turmoil stems from a 1998 law that gave residents more political autonomy but also set up a marine reserve extending 64km offshore.
Within the reserve, only tourism and local, small-scale fishing are permitted.
The increasing population of the islands has left many struggling to survive, with the number of registered fishermen doubling to more than a thousand.
In 1950 the total population of the islands was less than the number of fishermen is today; now it is close to 20,000.
"Giving into pressures that violate the law could deteriorate Ecuador's image and promote a lack of discipline with respect to legal norms," an alliance of eight conservation groups said in a letter to Ecuadoran President Lucio Gutierrez.