PORT Adelaide football manager Peter Rohde says the club had no choice but to let restricted free agent Danyle Pearce walk to Fremantle.

The Power announced on Wednesday they would not match Fremantle's offer to Pearce under the Gillette Free Agency Period.

Rohde told AFL.com.au's Trade Radio on Wednesday afternoon that Fremantle's four-year offer to Pearce was well above what the club was prepared to pay.

"To match the offer Fremantle had put up was really not an option for us," Rohde said.

"We think the offer that they've given him is very generous."

Fremantle put in a substantial restricted free agent bid for Pearce on Monday, the opening day of free agency, and Port had three days to make a counter offer.

Pearce was rookie listed by the Power at the 2005 NAB AFL Rookie Draft.

He played 154 games for the club, was named the 2006 NAB AFL Rising Star and was a member of the 2007 Grand Final side.

Pearce said in a statement on Fremantle's website that the decision to leave Port was a difficult one for him and his family, but he looked forward to making an impact at his new club.

"I would like to thank all at the Port Adelaide Football Club, especially my teammates whom I have shared the past eight years with," he said.

"I would also like to thank Ross Lyon and the Fremantle Football Club for the opportunity they have presented to me and look forward to the next chapter in my football career."

Fremantle's general manager of football operations, Chris Bond, said Pearce was a quality player who was very durable and capable of playing in a number of positions.

"He's been playing in defence recently for Port Adelaide, but we see an opportunity for him to play midfield and forward as well," he said.

"We think it's a great opportunity for him and a great asset for the club.

"His strengths are his speed and his ball use and we think that he's going to fit into the culture of our team.

"It's an exciting time for us and it's going to be an exciting time for Danyle."