It was obvious the Mariners were facing a tough choice when it came time to activate Michael Morse, and Monday they made it: veteran Jason Bay was designated for assignment.

Morse was recalled from his injury rehab assignment and activated from the 15-day disabled list, where he has been since injuring his right quadriceps on June 22. Morse will join the team Tuesday in Boston, when the Mariners begin a six-game trip against the Red Sox at Fenway Park.

Bay, 34, was attempting to resurrect his career in Seattle after down years in New York with the Mets, including a .165 average in 70 games in 2012. He made the Mariners out of spring training as a nonroster player and had his moments in the first half. But his playing time, and productivity, had begun to diminish.

In 68 games, Bay hit .204 (42 for 206) with 11 home runs and 20 runs batted in. Bay was just 3 for 29 with one double and one homer in July.

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The Mariners have 10 days to trade, release or outright the contract of Bay to the minors. He is a three-time all-star who exceeded 30 homers and 100 RBI three times in his career.

Morse, 31, is hitting .251 with 11 homers but has been hampered by injuries, including a fracture of his right pinkie finger as well as the quad strain, which he first hurt in late May. He was 6 for 24 with one homer and one double in his six-game rehabilitation stint with Class AAA Tacoma.

Larry Stone: 206-464-3146 or On Twitter @StoneLarry.