A seal that had been trapped in a fishing loch since December died during a rescue attempt, British Divers Marine Life Rescue (BDMLR) said.
The seal was first sighted at Rochford Reservoir in Essex on 12 December.
There were several attempts to rescue the seal, which was injured and consuming the lake’s fish stock.
The BDMLR said the seal was “shocked” with an anesthetic but “avoided capture” and died in the water.
“This is a very sad outcome from a very difficult situation,” a spokesman said.
“Rescuing any animal using the anesthetic carries significant risk, but in this case, the coalition felt it was worth taking.”
Marine rescuer Simon Dennis previously said the seal was likely to have made its way up the Roach River from the sea, through an inlet.
He said the harbor seal probably had ‘no incentive to leave’ the lake as it had ‘found itself in a branch of Waitrose’ and was ‘munching on fish’.
The reservoir is owned by Rochford District Council but Nick North, of Marks Hall Fisheries, has held the license for 11 years.
Mr. North was concerned about the seal consuming the fish in the lake, which he had stocked and done extensive work on.
“To see all of this lost to a seal entering a lake where it doesn’t belong is ridiculous,” he said previously.
The BDMLR previously said that tranquilizers “do not work well with [seals]” and could lead to drowning.
In a statement, the organization said the rescue attempt was being led by “a coalition of organisations” including BDMLR, Rochford District Council, South Essex Wildlife Hospital, police and the Environment Agency.
He said the seal “had a gaping wound on its hind flipper and a wound on its eye,” and rescuers hoped to heal the wounds and rehabilitate the seal before returning it to the sea.
“A specialist veterinarian successfully launched the seal with a special dart gun and anesthetic, but sadly, due to unforeseen complications, the animal escaped capture and is believed to have died under anesthesia while in the water.” , says the note.
The organization said there was “deep disappointment and sadness that the operation was not successful”.
“However, as the seal was under threat of being shot to remove it from the lake, it was felt it was worth trying to capture and relocate it to save its life,” he said.
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