A grey seal fond of an extra fish or two has been put on a strict diet after ballooning by more than 124kg (273lb) in nine months.
The seal, named Yule Log, is now close to the maximum weight for his species after keepers admitted giving in to his big pleading eyes.
But staff at the Cornish Seal Sanctuary, in Gweek, Cornwall, were shocked during his latest weigh-in when they were faced with just how much weight he had gained.
Yule Log - known as Loggy - now weighs 346kg (763lb) and his keepers said they will have to resist his charms to get him down to under 300kg (662lb).
Animal care assistant Jenny Lewis admitted she has a soft spot for the 24-year-old seal, and knew instantly she may be to blame for his expanding girth. "He's such a lovable character I haven't been able to resist giving him the odd extras at feeding time," confessed the 29-year-old zoology graduate.
In fact Miss Lewis was not just giving Yule Log extra helpings at the seal feed, she was also treating him to anything left over from penguin and sea lion feeds. Her bosses were not too hard on her though, saying they have all learned that Yule Log's pleas for extras are difficult to resist.
Supervisor Tamara Cooper said: "If he doesn't think he's getting his fair share he swats the water with a giant flipper and drenches whoever is holding the fish bucket. We're all going to be in for a few soakings in the coming months as we try to get Yule Log back in trim - but Jenny will be getting the most."
Staff at the sanctuary said Miss Lewis's penance is to now take charge of a new diet and exercise regime for the seal.
"From now on he gets only his allotted 2kg (4.4lb) of fish for breakfast and 1.5kg (3.3lb) for supper," Miss Lewis said. "And as well as his regular morning training session, there will be extra enrichment sessions every day where I have to make him work for his food. His fish will either be hidden in a ball that he has to chase round the pool and work with his flippers to get the fish out, or dragged back and forth on a food line to make him pursue it.
"He is already trained to target feed, which means putting his nose on a special stick we carry before he gets a fish, but from now on he will have to chase me up and down the side of the pool a few times before I let him reach it." Yule Log will also be subject to regular monthly weigh-ins to ensure he gets back to a healthier size. "The target is to get him back below 300kg (662lb) and then not to ease up on his new regime, to make sure he stays there," Miss Lewis said.