Researchers think they have finally found a potent shark repellent, following tests in the Bahamas.
If it proves successful the substance might one day protect divers, surfers and swimmers.
The team behind the repellent said more research was needed before it could be used to deter attacks on humans, but they hoped it could protect sharks, in decline worldwide because of overfishing, by reducing the numbers caught needlessly by long-line commercial fishermen.
“You introduce this chemical and they all leave,” said the lead researcher, Eric Stroud. “It works very, very well.”
The repellent, called A-2 because it was the second recipe tried, is derived from extracts of dead sharks. Fishermen have long noted that sharks will stay away if they smell a dead shark.
“We have something that really works, but research remains,” said Samuel Gruber, a marine biologist and shark expert who is helping conduct tests at the Bimini Biological Field Station.
Mr Gruber said the repellent appeared to carry a chemical messenger that triggers a flight reaction – something seen before in other fish.
He said more studies were needed to pinpoint the active molecule among a dozen or so varieties present in the recipe.
Tests have found the repellent effective on three species: the Caribbean reef, blacknose and lemon sharks. Studies are needed on other species.