LONESOME George has died, leaving the world one species poorer.

The only remaining Pinta Island tortoise and celebrated conservation icon passed away on Sunday, the Galapagos National Park Service said in a statement.

Estimated to be more than 100-years-old, the creature's cause of death remains unclear and a necropsy is planned.

Lonesome George's longtime caretaker, Fausto Llerena, found the tortoise's remains stretched out in the "direction of his watering hole" on Santa Cruz Island, the statement said.

Lonesome George was discovered on Pinta Island in 1972 at a time when tortoises of his type were already believed to be extinct. Since then, the animal had been part of the park service's tortoise program.

Repeated efforts to breed Lonesome George failed.

"Later two females from the Espanola tortoise population (the species most closely related to Pinta tortoises genetically) were with George until the end," the park service said.

In honour of Lonesome George, the park service said it was convening an international workshop in July on management strategies for restoring tortoise populations over the next decade.

The Galapagos Islands, situated about 1,000km off Ecuador's coast, is considered a haven for tortoises.