Blanco, 41, is a 16-year Major League veteran who has played for 10 different teams. Blanco has a well-earned reputation as a strong defensive catcher, the Mariners said. He's thrown out 40 percent of baserunners who have attempted to steal against him.
Blanco signed with Toronto in the offseason and was released on June 10. He played in 15 games with the Blue Jays, and caught in 13, games including 11 consecutive starts by knuckleballer R.A. Dickey.
Shoppach batted .196 in 35 games this season with Mariners. He hit seven doubles, three home runs and nine RBIs. He struck out 45 times.
The Mariners now have 10 days to trade, release or send him to the minors.