Turtle news from the other side of the world, published in The Guardian on 12/11/2010 by Alok Jha

Study reveals enormous levels of illegal turtle harvesting in Madagascar

A green turtle hatchling. Photograph: Joe McDonald/Corbis

 

Up to 16,000 of the world's rarest turtles are being caught every year by villages in just one part of Madagascar, a year-long survey has revealed. The study is the first direct assessment of the level of exploitation of turtles in Madagascar. Until now, measuring information on the small-scale turtle catches in the most remote areas has been tough, because of difficulties accessing these regions. "Because turtles are an endangered species, it's important for us to know what's going on in the region so we can work with the local community to find a sustainable way forward," said Annette Broderick of the Centre for Ecology and Conservation at the University of Exeter, who led the latest survey. The harvesting of turtles is illegal in the region, but the ban is not enforced for various cultural and practical reasons. Broderick's team trained villagers to monitor turtle catches in Toliara, part of a remote south-western region of Madagascar. In 12 major villages along 60km of coastline, locals collected biological and fisheries data and photographed each catch. In total, they documented 699 marine turtle landings. The majority of these were green turtles, the commonest species in the water, but the catches also included the more endangered hawksbill turtle. "When we contextualise our data with those of previous studies elsewhere in the region, we conservatively estimate that the annual turtle catch in the southwestern province of Madagascar is between 10,000 and 16,000," wrote Broderick in a paper published in the journal Animal Conservation. Even this estimate is likely to be on the low end, Broderick said. "In reality it's likely to be much larger than that. We don't have a good handle on how the in-water populations have changed over the years." All species of marine turtle have experienced population declines in recent years and are included in the IUCN red list of endangered species. In Madagascar, all marine turtles are protected from domestic exploitation by presidential decree but the laws are not enforced because of lack of capacity for implementation along the enormous length of the coastline, and also the cultural history of turtle harvesting. Frances Humber of Blue Ventures Conservation said that catching turtles for meat is an important part of Malagasy culture in many coastal populations. "But the villagers also understand the importance of ensuring the future of this resource. This study is a great way of involving communities in the process of finding a sustainable way forward. Obviously we can't be sure every turtle catch is reported, so we view the figures from this study as a conservative estimate which is still nevertheless very valuable for informing policy." Stopping the decline in turtle numbers would be a matter of working out where the harvested turtles are being used. "The important thing is whether the harvest is for subsistence use or for commercial exploitation," said Broderick. "If it's for villages for subsistence use, it's quite a different management issue. It's very difficult to tell people that they're going to have to stop using a certain source of food, especially in developing nations where it's an important source of food. There's a danger with these kinds of harvests that these turtles are being taken to larger markets and possibly being exported out of the country." Humber added that Madagascar should not be singled out in harvesting turtles. "We'd expect similar harvests in many countries in the tropical coastal developing world, so this isn't an isolated issue, but clearly it is a cause for concern when dealing with endangered species. It's possible the model for this study could be used elsewhere to get a better idea of numbers. Until we get more details, it's difficult to draw conclusions about what is sustainable and how we can find solutions. Clearly making turtle fishing illegal hasn't worked, so we need to work with communities to promote sustainable practices."

Leatherback turtles breathe in for buoyancy

Not from the beach but turtle news all the same! By Victoria Gill  Science and nature reporter, BBC News

Leatherbacks use their lungs as buoyancy aids

Leatherback turtles, the ocean's deepest-diving reptiles, control their buoyancy simply by breathing in, scientists have found.

Researchers describe in the Journal of Experimental Biology how the turtles regulate their dives through the volume of air in their lungs.
This allows them to glide and forage for food at a variety of depths.
Scientists believed that the animals would exhale before diving, to avoid gas bubbles forming in their bodies.
US and UK scientists monitored the turtles' diving by attaching small data loggers to the animals' backs.

They're able to regulate the amount of air they take in when they're diving Sabrina Fossette

Sabrina Fossette from the University of Swansea in Wales led the study.
She and her colleagues attached the data loggers to five female leatherbacks in a wildlife refuge in the Caribbean.
"In addition to the depth, we could measure their acceleration," Dr Fossette told BBC News. "So we were able to model each dive in 3-D.
The researchers saw that the leatherbacks started their dives by actively swimming as they descended.
"Then, at some point during the dive they started gliding," said Dr Fossette.
"The turtles started gliding at deeper depths during deeper dives, suggesting they regulate the amount of air they inhale before diving."
This enables them to use their lungs as buoyancy aids to precisely counteract their weight.
The ability to glide at a variety of depths allows leatherbacks to conserve energy; it also means they are more flexible in terms of where in the ocean they can feed.
"Leatherbacks forage on gelatinous plankton," said Dr Fossette, "which can be found either at the surface or really deep in the ocean."
'The bends'

Dr Fossette and her team attached the loggers to five female turtles

Many other diving animals, including hard-shelled turtles and penguins also inhale before they dive, but the researchers we were surprised to see the same behaviour in leatherbacks because the creatures are such deep divers.
Scientists have recorded the animals reaching depths of up to 1,000m - the deepest leatherback dive ever recorded was more than 1,200m.

"Stick-on" data loggers allowed the scientists to monitor the turtles' dives

So the researchers expected that the animals would exhale before a dive, in order to avoid decompression sickness.
Otherwise known as the bends, this can occur when dissolved gases in an animal's (or human's) blood form bubbles inside their bodies.
"Many deep divers - notably deep-diving mammals - exhale before diving to minimise the effects of decompression," said Dr Fossette.
"Leatherback turtles share many physiological and physical features with deep-diving mammals and therefore we would expect them to exhale."
It seems that the turtles' body temperature increases the solubility of the gases and therefore decreases the risks of bubbles forming.
This tagging experiment was designed by Rory Wilson, also from the University of Swansea, and Molly Lutcavage from the University of New Hampshire, US.