DULUTH (AP) - Officials say the Duluth-Superior shipping season is winding down for the winter, but there's never much down time on the waterfront.

The Soo Locks are scheduled to close for the season on Friday, and the Duluth Seaway Port Authority says seven ships will spend the winter in the Twin Ports. The last one - the 1,000-foot Paul R. Tregurtha - is expected to arrive sometime next week, marking the official end of the 2015 Great Lakes shipping season for Duluth-Superior. The last oceangoing ship, or "saltie," of the season left Duluth on Dec. 18.

Hundreds of workers will spend the next eight weeks doing heavy-duty maintenance and repairs so the seven vessels are ready to sail when the Soo Locks reopen March 25 and the 2016 shipping season gets underway.