New research has revealed up to 16,000 endangered turtles are being caught each year by villagers in just one region of Madagascar, despite a government ban.
Researchers from the University of Exeter and Blue Ventures Conservation say the figure, thought to be a conservative estimate, is the first direct assessment of turtle exploitation on the island.
The study highlights the extent of small-scale fishing, traditionally very difficult to monitor, and could be vital in finding a way to sustainably manage turtle fishing in the region.
Dr Annette Broderick, from the Centre for Ecology and Conservation (Cornwall) at the University of Exeter, said: "We conducted this study because we know this small-scale, artisanal fishing is going on despite it being illegal to catch turtles under Malagasy law.
"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."
Traditionally it has been very difficult and expensive to get data on small-scale, artisanal turtle catch because of the difficulty of access to these remote areas.
This research used a new approach, involving locals in the process by paying a village representative to document each turtle caught, including taking a picture of each one.
Frances Humber, who works for Blue Ventures Conservation, said: "Catching turtles for their meat is an important part of Malagasy culture for many coastal people, 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."
The research monitored the harvest of marine turtles at 12 coastal villages in Madagascar and documented a total of 699 marine turtle landings, including four species with the majority being green turtles.
Combining these data with those from previous studies in the region produced a conservative estimate of annual turtle catch in the south-western province of Madagascar of between 10,000 and 16,000.
Frances Humber admits the figures from this study are a cause for concern, but insists Madagascar should not be singled out.
"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," she said. "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."
The research is due to be published in Animal Conservation.
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