Fears that a crocodile had set up home in a river have been allayed after zoologists said it was more likely to be a giant turtle.
A crocodile was thought to be the original culprit
The crocodile theory began when boat trippers on the River Lea in east London, saw a Canada Goose apparently pulled under water at speed.
But experts say an alligator snapping turtle, which can grow to about two metres, is a more likely culprit.
The creature may have been a pet which was released into the wild.
Mark Gallant, of the Lea Rivers Trust, who was on the boat, told BBC News it would be frightened away by the sound of a boat motor so traps would have to be set for it.
He said: "We are going to have to try baiting some traps because obviously we can't have a creature that's the top predator preying on our wildlife - you'll have none left.
"Someone might buy it as a baby turtle. After they've had it in their pond, or bath, or whatever they are going to keep it for a while and the thing starts to grow and grow and grow and grow.
"Obviously they can't keep it in their homes anymore so what do they do? They think they are doing a good thing for the actual animal by putting it into a river or stream."
Mr Gallant said the River Lea is the perfect place for the turtle, because the waterways there are similar to their natural habitat in North America.
It provides the creature, which has algae on its back and can stay under the water for an hour, with plenty of places to hide in mud and behind hanging vegetation.