Only the cellar-dwelling Florida Panthers have a worse conference record than the Lightning (13-17-1), who started the strike shortened season 6-1 but have lost six of their past 10 games.
"Guy has poured his heart and soul into the Lightning organization for these past three years and we appreciate all the work he has done," team general manager Steve Yzerman said in a statement.
"But ultimately I am not satisfied with the direction we are heading and I believe making a change today is in the best interest of our franchise."
Assistant coaches Martin Raymond and Dan Lacroix were scheduled to share coaching duties in the Lightning's game against the Winnipeg Jets later on Sunday.
Boucher, 41, compiled a 97-78-20 record with the Lightning. His best finish came in his first season (2010-11) when Tampa Bay went 46-25-11 to place second in the Southeast Division before losing to Boston in the conference finals.
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