Fisherman say a seal which is eating all the fish in the river Wharfe should be removed.
The Environment Agency says there is little it can do to move the seal
The Environment Agency said the seal - first seen at Ulleskelf near Tadcaster - was evidence that the river waters and fish stocks are good quality.
It said seals were resident in most estuarial waters and had been seen in the Ouse as far up as Linton.
But local fisherman have complained the seal is eating all the fish and they are powerless to do anything about it.
Dennis Lemon, president of Leeds and District Amalgamated Society of Anglers, said: "If it was killing fish to feed on then fair enough but just to bite lumps out of fish, kill it and then go back and do the same again to another one - its just killing for fun,"
"We've got one salmon river in Yorkshire, which is the Esk, and commercial anglers get a license.
"Now if a seal starts attacking those nets with salmon in them they're permitted to shoot them. Now why can't we?
"It's damaging our fish stocks. If it kills one salmon in a net they can shoot it but we can't."
A spokesman for the Environment Agency said there was very little they could do to move the seal.
"We are a victim of our own success in improving rivers and fish stocks.
"If we found some way of moving it, it could just swim back up. It's a wild animal."