The intrepid seals follows the fisherman's catch into his keep net on the Broads.
It causes mouth sores and lesions on pups, making it hard for them to eat, and some starve to death.
The animal charity says the bird's death shows why the traps should be banned from sale.
Daffodil and Trifle are taken back to the sea after fears they were eating too many of the river's fish.
A van driver aged in his 30s dies after a crash which closed a major road for more than 14 hours.
The crash, involving a lorry and a van, left the stretch shut in both directions for several hours.
A major road is shut for more than four hours following a collision.
The charity says a tonne of salt is used by a wildlife centre every few days to treat the animals.
The RSPCA is appealing for witnesses after the shot bird was found in Wisbech.
