When turtles come onshore to nest, a transmitter is fitted to their shells in a painless process using fibreglass cloth and resin. The transmitter has a smart switch that is sensitive to sea water. When the turtle comes up to the surface to breathe, the transmitter switches on and, using a global system of satellites, it sends a signal up to an orbiting satellite which keeps constant track of it. The information is relayed to a receiving station in France, then passed on to scientists and conservationists throughout the world via email or a dedicated website.
To save battery life, the transmitter automatically switches off when under water and it can be programmed so that it is only in action for certain amounts of time. Its duration will obviously depend on how active the turtle is, but normally it will last around one year. At some point after it has outlived its usefulness, the adhesives that have clamped it to the shell will crack and the unit will simply drop off. At no time will the turtle have felt any pain or discomfort; it will likely not even be aware that the transmitter had been attached to it.
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