The United Nations Environment Program said although turtle populations have increased in South Africa during the past 40 years, their numbers in eastern Australia and Madagascar have seriously declined.

Although the most common threat to marine turtles are their natural predators, incidental capture in coastal harvesting, unsustainable egg collection, poaching and a resurgence in destructive fisheries, such as the use of dynamite and poison, contribute to their decline significantly, the U.N. agency said.

"Coastal development -- especially for tourist facilities -- has been proceeding very fast in much of the Indian Ocean region," said Jack Frazier, chairman of the UNEP's turtle advisory committee. "The chances for negative impacts on nesting beaches, as well as on inshore foraging and resting areas for turtles, have increased and are continuing to increase dramatically."

Frazier said delegations from more than 30 nations are meeting in Bali this week to review implementation of a conservation and management plan that gives particular attention to coastal development issues and fisheries interaction with marine turtles.