MANCHESTER — Blue Jays prospect Marcus Stroman, a relief pitcher who had been throwing lightning bolts for the New Hampshire Fisher Cats, has been suspended 50 games by Major League Baseball after testing positive for a banned substance.

Stroman left the Fisher Cats after testing positive for a stimulant, methylhexaneamine, according to the Blue Jays.

The Duke University product signed for $1.8 million after being selected in the first round (22nd overall) of the MLB entry draft in 2012.

After starting the season with Class-A Vancouver, the 21-year-old posted a 2-0 record, a 3.38 ERA and eight strikeouts in eight innings with New Hampshire, Toronto’s Double-A affiliate.

The Blue Jays issued a statement attributed to Stroman on Tuesday afternoon.

“Despite taking precautions to avoid violating the minor league testing program, I unknowingly ingested a banned stimulant that was in an over-the-counter supplement,” the statement read. “Nonetheless, I accept full responsibility and I want to apologize to the Toronto Blue Jays organization, my family, my teammates, and the Blue Jays fans everywhere. I look forward to putting this behind me and rejoining my teammates.”

Fisher Cats manager Sal Fasano and pitching coach Tom Signore directed any questions about the suspension to the Blue Jays.

“This suspension is unfortunate, and we are disappointed by this development,” Blue Jays general manager Alex Anthopoulos said. “The Toronto Blue Jays, however, fully endorse Major League Baseball’s drug-testing policy and support the discipline taken today.”

Stroman is just the most recent minor-leaguer who recently has tested positive for a banned substance. Mark Donato of the Royals, Joshua Sale of the Rays and Michael Albaladejo of the Nationals all have been suspended 50 games this season.