(Bloomberg) -- The St. Lawrence Seaway, a major maritime trade route between Montreal and the Great Lakes, is shut down after union workers walked off the job early Sunday morning.

The strike is expected to affect the movement of grain and other goods along the Seaway, a trade artery jointly managed by Canada and the US that stretches between Lake Erie and Montreal. The company is seeking a targeted back-to-work order.

“This impasse is extremely unfortunate but our members remain committed to getting a fair agreement,” Unifor president Lana Payne said in a release.

Under what’s known as “pattern bargaining,” Unifor, Canada’s largest union, recently won wage increases for its members who work for Ford Motor Co. and General Motors Co. The company that runs the Seaway says that the union is now seeking a similar deal for its workers there. 

The St. Lawrence Seaway Management Corp. says the union is looking for “wage increases inspired by automotive-type negotiations” and has “minimally moved” from initial demands.

The company said there are no ships currently waiting to exit the Seaway “but there are over 100 vessels outside the system, which are impacted by the situation.”

It is seeking a ruling under the Canada Labour Code that would force the union to provide workers to ensure the movement of grain along the route.

“In these economically and geopolitically critical times, it is important that the Seaway remains a reliable transportation route for the efficient movement of essential cargoes between North America and the remainder of the world,” St. Lawrence Seaway Management president and Chief Executive Officer Terence Bowles said in a release. 

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