Nature lovers have called for intervention to restrict anglers fishing on Hampstead Heath ponds after another cygnet was injured by a discarded fishing line.

The cygnet had to undergo surgery after the fishing hook and line became wedged in its oesophagus.

An adult female swan also got tangled up in the fishing line.

This picture of the cygnet recovering from the operation was taken by Ron Vester. He said: “On Saturday Heath rangers quickly responded to a cygnet on Hampstead No.1 pond who had a fishing line and hook in its oesophagus.”

He said the swan was taken to Shepperton Swan Sanctuary where the surgery was performed.

“My photo shows the little guy in recovery ward so all looks promising,” said Mr Vester, known for keeping an eye out for the swans which live on the Hampstead Heath ponds.

Sian Whitehead, of Sandstone Place, Highgate, said: “Fishing tackle-related injuries are the biggest single cause of swan rescues – estimated at 3,000 a year.

And according to the RSPCA the number of swans admitted to their wildlife centres as a result of angling equipment has more than tripled.

Back in July when this happened previously to another cygnet on the Heath the opinion seemed to be: ‘there is nothing that can be done to stop this as long as anglers have a licence’.

“I would suggest that having a licence to fish is not the same as having a licence to harm other wildlife. As long as they are allowed to fish in the ponds where the swans and young cygnets swim, which they are, and for as long as there is an acceptance that there is nothing more to do to prevent these type of injuries happening, then it will keep recurring.

“This apathy towards the situation is also now part of the problem.

She concluded: “I would hope those in charge will try and implement something different to turn this situation around.

Doing nothing changes nothing.”