The 43 meter long United States Coast Guard icebreaker tugboat Bristol Bay suffered a fire while on the St. Clair River near Sarnia, Ontario, Canada.   The fire started in the Bristol Bay’s smoke stack while the vessel was conducting a training exercise.   The vessel dropped anchor while the crew sprayed water into the stack until the blaze was extinguished.  No reports of injuries and the vessel suffered only minimal damage.  The Bristol Bay primary responsibility is opening and maintaining shipping lanes in the Great Lakes.