Three species of marine turtle, which hatch on tropical beaches before swimming to feeding grounds off the Cornish coast, are at risk from fishermen's nets, power-boat propellers, oil contamination and internal blockages from plastic debris they mistake for food.
To try to ease the problem, the Cornwall Wildlife Trust is launching a "Be turtle-aware" message for World Oceans Day this Sunday. The trust's education officer, Mark Nicholson, said: "The leatherback turtle, which can grow to over eight feet, is the one we see most often. If people know turtles are here at all, they tend to assume that they've wandered off course from the tropics. In fact, they migrate here on purpose to feed - they're part of our wildlife and we have a duty to look after them."
The Trust is launching a turtle code, which will advise fishermen and others on how to help turtles in distress.