Scientists have identified the world's 11 most threatened turtle populations. The International Union for the Conservation of Nature (IUCN), which produced the report, hopes that it will be used as a guide to conserve the threatened animals. Three of the populations were Olive ridley turtles in the Indian Ocean. By locating populations of turtles - genetically related groups that nested, fed and moved around the same areas of an ocean - scientists showed precisely where conservation efforts are most urgently needed. They published the report in the online open access journal Plos One. Some of the "most dangerous places" for turtles are India and Sri Lanka and Bangladesh. One particularly vulnerable population of loggerhead turtles relies on both India and Sri Lanka for its nesting sites. Four populations of hawksbill turtles - in the north-east Indian Ocean, the east Atlantic and the east and west Pacific Ocean - are on the most threatened list. The species is under particular threat worldwide because of huge demand for its beautiful shell, which is used to make tortoiseshell jewellery and ornaments.