Canada's Algoma Tankers was served with a strike notice from a local seafarer's union after contract negotiations broke down.
The Canadian Merchant Service Guild says the 72-hour notice covers 32 navigation officers working for the tankers unit of Algoma Central.
The labour action will hit all six of Algoma's owned tankers and one other vessel under long-term hire.
The Guild says its members will walk off their posts once the vessels are safely moored starting 21 October.
