SAULT STE. MARIE, Mich. — U.S. and Canadian Coast Guard cutters are breaking ice at several locations in the Great Lakes in preparation for resumption of the commercial shipping season.

The navigational locks at Sault Ste. Marie are scheduled to reopen Sunday after the winter shutdown, allowing shipments of iron ore, coal and other bulk cargo between Lakes Superior and the other lakes.

Coast Guard crews are clearing pathways in Lake Superior, Lake Michigan’s Green Bay, the St. Marys River, the Straits of Mackinac and Lake Huron’s Georgian Bay.

Most of the work will be in Superior, where more than 50 percent of the surface is still covered with ice.