PORTLAND — The Boston Red Sox and Portland Sea Dogs have agreed to extend their Player Development Contract for an additional four years.

The extension keeps the Red Sox Double-A affiliation in Portland through the 2018 season.

The Sea Dogs and Red Sox last extended the affiliation in January 2011, when a twoyear extension was announced, taking the contract through the 2014 season.

“As we prepare for our 20th season of Sea Dogs baseball we are thrilled to announce this new agreement,” said Bill Burke, chairman of the Sea Dogs. “It is an honor to be associated with the Boston Red Sox, one of the greatest franchises in professional sports, and we are pleased to let our incredible fans know that this relationship will continue well into the future.”

The Sea Dogs originally entered into a contract with the Red Sox following the 2002 season, ending a nine-year affiliation with the Florida Marlins. Upon changing affiliations, the Sea Dogs changed colors from teal to red and blue. Additionally, the Sea Dogs erected a likeness of Fenway Park’s famed Green Monster in left field at Hadlock Field. The skyboxes at Hadlock Field were also renamed in honor of Red Sox legendary hitters.

The Sea Dogs will open their 20th season on April 4 at 6 p.m. against the Trenton Thunder at Hadlock Field.

Tickets can be purchased by calling the Sea Dogs Ticket Office at 879-9500 and online at www.seadogs.com