PORTLAND — The Portland Sea Dogs will open and close their 20th season at home against the Trenton Thunder.

The Sea Dogs season opener will be April 4 at 6 p.m. at Hadlock Field against Trenton. The teams will close the Eastern League regular season with a four-game series at Hadlock Field.

The Sea Dogs will be in their 11th season as the Double-A affiliate of the Boston Red Sox. Trenton is the Double-A affiliate of the New York Yankees.

Thirty-three of Portland’s 71 home games will be played on weekends next summer. In addition, the Sea Dogs will have home games on Father’s Day (June 16, 1 p.m., against Akron), the Fourth of July (New Britain, 6 p.m.) and Labor Day (Sept. 2, 1 p.m.).

The annual Field of Dreams game will be on Sunday, Sept. 1, against Trenton at 1 p.m.

The Thunder will play 11 games at Hadlock Field next summer. The New Hampshire Fisher Cats, the Sea Dogs’ rival in New Hampshire, will play 10 games at Hadlock.

Individual tickets for the 2013 season will go on sale on Nov. 3 at 9 a.m. at the Hadlock Field ticket office.