Littlehampton's seal has been named after a longstanding helmsman at the town's RNLI station.
Littlehampton Harbour set up a poll to name the seal which has been frequently sighted in the River Arun and the harbour.
Today, it was announced on the harbour's Facebook page that Gavin had been chosen as the winning name, with 674 votes and 74 per cent of the vote.
The seal's namesake, Gavin Simmons, said it was a 'lovely gesture' and came as a surprise. He said: "Most people want to have a ship named after them, but I got a seal.
"It's a good laugh, it made me chuckle."
The other name put forward was Jumna, a paddle steamer tug that worked Littlehampton from 1890 to 1915. A model of the original Jumna is mounted on the harbour office's southern wall.
Gavin, 41, from Littlehampton, joined the town's RNLI station as a volunteer in 2002 and has worked on the RNLI lifeboat station on the River Thames in London for more than 10 years.
He said he had seen the seal while out and about during callouts, but it was not the most unusual animal sighting he had seen in his time.
He said: "We had a job a good few years ago where a deer was seen swimming down the River Arun.
"We've also been called out to cows seen in the river near Arundel."
He thanked his friend Mark Pryor for campaigning for votes.
Prior to Gavin's name being chosen, Mark posted on Facebook saying: "By voting Gavin you are not only voting for the man himself, but the whole RNLI and everything that they stand for, their dedication to saving lives and making our seas safer for more people to enjoy."
Mark also said Gavin would dress as a seal for Littlehampton's bonfire night - but Gavin said his friend might have taken that one a little too far. He said: "He might have to do it himself. He can be my stunt double."
A Facebook page has been set up for the seal, called Gavin the Littlehampton Harbour Seal.
Less than two weeks ago, a paddleboarder from Rustington got up close and personal with the town's unofficial mascot - and described the experience as 'amazing'.