FREMANTLE free agent Zac Clarke has signed a one-year contract extension with the Dockers.

Clarke, 26, was an unrestricted free agent and will again have that status at the end of 2017, assuming he does not agree to another contract with the club before the end of next season.

He told being out of the country on holiday meant contract talks had dragged on longer than expected.

"Being overseas pushed it back a bit longer, but I've been here for a while now so it's really good to add another year," Clarke said.

He had knee surgery at the end of the season and won't join in full training until around Christmas.

"I'll be back at the club in a fortnight and training in some aspects but I won't be training just yet," Clarke said.

"I had knee surgery straight after Peel's (WAFL side Peel Thunder) Grand Final, so I'll just work my way through rehab, but I don't think I'll be that far behind the rest of the group.

"I should be ready and raring to go by round one. I'm hoping to join the main group just before Christmas."

After lining up in the senior side in 13 matches this season, Clarke finished the year in the WAFL.

Dockers list manager Brad Lloyd told the club website Clarke would help support fellow big men Aaron Sandilands and Jonathon Griffin.

"It's really good to agree terms with Zac for another year and we look forward to seeing him represent the club next season," Lloyd said.

"He's an experienced big man and will play an important role in our ruck department."

Clarke has played 101 matches for the Dockers since being drafted at No. 37 in 2008.

The news comes in the wake of Michael Barlow joining Gold Coast as a delisted free agent on Tuesday.

Fremantle lost 13 players this offseason through retirement, delistings and free agency.