DETROIT (AP) - U.S. Coast Guard crews are conducting icebreaking operations in Great Lakes bays. The cutter Bristol Bay begins breaking ice Thursday morning in Lake Huron's Saginaw Bay Shipping Channel and is scheduled to continue through the day. The crew of the 140-foot vessel based in Detroit will be escorting the tug Samuel de Champlain, pushing the barge Innovation from the Saginaw Bay area to Essexville. The ice in these areas is unstable and the Coast Guard is advising everyone to stay clear. It's part of Operation Coal Shovel, which breaks ice in Lakes St. Clair, Erie and Ontario and the southern part of Lake Huron, as well as the St. Clair and Detroit river systems. Another Coast Guard team is breaking ice in Lake Michigan's Green Bay.