The Seattle Mariners' biggest cheerleader is officially part of the team.

Tucker the Mariners Pup is featured in the club's media guide for the 2024 season. It's his first time being included in the program.

Tucker is listed in the Coaching Staff section with the Behind the Scenes team, including the team's strength and conditioning coaches and mental performance coach. There's even a win-loss record: The Mariners are 127-104 (.550) since Tucker joined the club during the 2022 season.

"He enjoys playing fetch, visiting the clubhouse kitchen and running in the outfield," the guide said of their furry friend.

The Seattle Times reporter Adam Jude first pointed out on social media Tucker's inclusion in the media guide.

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In July 2022, the team started a social media account for Tucker, a lab/retriever mix that they adopted.

"I’m gonna get to hang out at the ballpark all the time, travel with the squad and enjoy my very own unlimited supply of baseballs," a post from August of that year said with a picture of Tucker lying on the field. "Doesn’t get better than this!"

@MarinersPup now has more than 26,000 followers on X, formerly Twitter, and more than 13,000 fans on Instagram.

Seattle made history in Tucker's first season by snapping a 21-year playoff drought. Despite a record-breaking campaign from Julio Rodríguez, they missed the postseason last year with an 88-74 record, finishing third in the AL West.

The team's mascot is Mariner Moose, who was introduced in 1990 at the Kingdome.

Hank The Dog was a walk-on for the Milwaukee Brewers after the team found him in 2014. The New York Mets also have Seaver, named after Hall of Fame pitcher Tom Seaver, a service dog in training who entertains fans on game day.