At least 10 stingrays have been found dead in Queensland waters in what are feared to be revenge attacks for the death of Steve Irwin, the popular Australian television naturalist. Irwin died last week after a stingray speared him in the heart with a poisonous barb while he was filming at the Great Barrier Reef. Wildlife experts said the ray must have felt trapped between him and the cameraman, since the creatures use the serrated barbs in their tails only when under threat. Wayne Sumpton, a senior biologist in Queenland's fisheries department, said two rays were found dead yesterday, with their tails cut off, at Deception Bay, north of Brisbane. Another six were found dead at Hervey Bay, a beach farther north. Mr Sumpton said it was not clear whether the incidents were prompted by the death of Irwin, 44, whose Crocodile Hunter documentaries were watched by more than 200 million people worldwide. "At the moment, that is just speculation," he said. "We do find dead stingrays with their tails cut off from time to time. People usually do it if they are worried about getting stung, or they just do it maliciously, but it is pretty rare." News of the dead rays prompted distress among Irwin's former colleagues. Michael Hornby, executive director of his conservation trust, Wildlife Warriors Worldwide, said killing rays ran counter to everything Irwin had stood for. "We just want to make it clear that we will not accept and stand for anyone who's taken a form of retribution. That's the last thing Steve would want. We are disgusted and disappointed that people would take this sort of action to hurt wildlife." Stings from the toxic barbs, which can be up to 20cm long, are not uncommon. But Irwin is believed to have been only the third person killed by a ray in Australian waters. Most people suffer painful but non-lethal wounds in their feet or legs.