The Port of Lyttelton has been threatened with a string of strike days if a pay dispute with the Rail and Maritime Union is not resolved.
Talks between the port and the workers ended last week with what the union described as only a slight improvement on the port's original offer.
Port chief executive Peter Davie said the union's approach to using this type of rolling strike action is not normal, and the company was surprised to learn of the plan.
"Normally you would get a strike notice for a period of time or infinite time until the issues are resolved so we're a little surprised that the RMTU are issuing daily strikes."
He said the port and the union are set to meet for mediation on Wednesday, and he is feeling optimistic.
Talks with workers ended last week with what the union described as only a slight improvement on the port company's original pay offer.
The port has offered workers a remuneration increase of 3-percent over 18 months, backdated to September.