More than 30 scientists and several giant tortoises are being held hostage by striking fishermen in the Galapagos islands.
The Galapagos Islands are famous for their tortoises
The fishermen are demanding greater freedom from conservation measures that restrict their activities.
But local environmentalists say the measures are vital for the islands.
The Galapagos, a cluster of islands 1,000km (600 miles) west of Ecuador's coast are home to exotic sea lions, iguanas, tortoises and birds.
The fishermen have surrounded the Charles Darwin research station that is known for breeding giant tortoises and are refusing to allow any food or supplies into the compound.
Inside the compound on the island of Santa Cruz, are 33 people, mainly scientists and a colony of the rare reptiles.
The fishermen are demanding to be allowed to fish for sharks using long lines and also want large cruise ships to be allowed to dock on the islands.
But environmentalists argue that easing the regulations would deplete natural resources.
They have urged the Ecuadorean government to resist the fishermen's demands and to uphold a scheme that gives Galapagos residents a say in their surroundings.
In a letter to the Ecuadorean president, an alliance of eight conservation groups said: "Giving into pressure that violates the law could deteriorate Ecuador's image and promote a lack of discipline with respect to legal norms."
Although the protest has so far been peaceful, there are serious concerns about the safety of the scientists and the tortoises.
The 19th Century British naturalist Charles Darwin's theory of natural selection was inspired by the Galapagos.