Muse was fully weaned when he was was found in a thin condition on 11 December.
West attended the location and said she had concerns about him immediately as he had “obvious rolls of skin” that should have been filled with blubber.
“When I initially assessed him, little did I know that he had travelled such a long way in such a short time.”
The seal had been checked by the British Divers Marine Life Rescue (BDMLR) four days earlier and was marked as being located at Port Gaverne, in Cornwall.
West said it was a “really long swim for a young pup” resulting in Muse losing a considerable amount of weight on his journey.
Ryan Walker, a wildlife supervisor at the RSPCA, said the seal was “underweight and with a possible respiratory infection” when he arrived at their centre.
But with the support of West and her team, Muse had consistently gained weight – showing he can compete with other seals for his share of the fish.
“His last weight was measured at 41.5kg (6st 7lb) – nearly tripling in size since he was picked up on the beach,” Walker added.