Port Timaru confirms that it will lay off 50 of its 74 employees over the next few weeks.
Port chief executive Jeremy Boys says there will be job losses throughout the organisation, with more than half in management and administration and more than two-thirds in operations.
About 30 are full-time jobs.
Maersk Shipping and Hamburg Sud previously announced they were pulling out of the Timaru container trade.
Mr Boys says staff will have a chance to give feedback before the cuts are finalised.