Dockworkers at the Port of Montreal launched a strike Monday morning.
The longshore worker's union failed to reach an agreement with the Maritime Employers Association despite discussions that continued until 1 a.m.
The union says the port-wide strike relates to scheduling and wage conditions.
The employers association says it believes the solution lies in a truce that would result in binding arbitration if no agreement is reached after two months.
The strike, which kicked off at 7 a.m., shut down activity at Canada's second-largest port with the exception of grain transport and shipments to Newfoundland and Labrador.
The labour action by more than 1,100 longshore workers, who have been without a collective agreement for nearly two years, comes after a series of temporary strikes by the Canadian Union of Public Employees over the past six weeks saw several ships diverted ports in Halifax, New York City and Saint John, N.B.