Stranded Rochford Reservoir seal killed in failed rescue attempt by marine experts

A seal that closed down a fishing lake after making it his new home has been killed in a rescue attempt that went wrong.

The animal drowned after being shot with an anaesthetic dart, said experts who had been leading attempts to capture it.

“Sadly, due to unforeseeable complications, the animal avoided capture and is believed to have passed away under the anaesthesia while in the water,” they said.

The common seal, nicknamed Nelson by locals, nipped over the bank and into Rochford Reservoir more than six weeks ago after swimming up rivers from the sea.

The animal had been eating its way through the reservoir’s fish stocks, with one expert comparing it to being “locked inside a branch of Waitrose”.

Groups, including British Divers Marine Life Rescue, Rochford Council, South Essex Wildlife hospital, Essex Police and the Environment Agency, had been working together to move the seal.

Rescuers had previously told ITV News Anglia they did not want to resort to tranquilising the seal because of how dangerous it was for the animal.

At the time, Simon Dennis, of the British Divers Marine Life Rescue, said "It's incredibly risky. They will just go into their breathing reflex and drown as soon as that's done."

The group expressed “deep disappointment and sadness” following the seal’s death at the weekend, adding that the rescue operation had come with “significant risk”.

But it said concerns about the animal's health and risks posed by others, as well as the previous failed rescues, had forced its hands.

“As the seal was under threat of being shot in order to remove it from the lake, it had been deemed worth trying to catch and relocate it in order to save its life,” said the BDMLR.

“This is a very sad outcome from a very tricky situation. Rescuing any animal using anaesthetic holds significant risk, but in this case the coalition deemed it was worth taking.”

The seal - also known as a harbour seal - had an open wound on its rear flipper and an eye injury and rescuers were keen to assess the animal’s health, treat the wounds and, after a period of rehabilitation, return it to the sea where it belonged.

A specialist vet had managed to dart the seal but rescuers had been unable to capture it "due to unforeseeable complications" and it drowned once the anaesthesia took hold.

It was one of the biggest news stories of our time - and it's still not over. So what did Boris Johnson know about Downing Street’s notorious parties?

With fresh revelations from our Number 10 sources, in their own words, listen to the inside story...