Meanwhile the more complex operations under the crane would continue to be performed by manual straddles.
Chief executive of Ports of Auckland, Tony Gibson, said exact numbers wouldn't be known until late 2017 or early 2018, around a year before implementation.
"Auckland freight growth is relentless. We're reaching the limit of what we can do with our current technology.
"We can't go out so we need to go up, and for that automation looks the best bet," he said.
"If the proposal proceeds we would look to redeploy staff into other roles."
Ports of Auckland spokesperson Matt Ball said unions had been advised that automation was being investigated earlier in the year so the announcement was not "unexpected".
A decision on the proposal will be made in early 2016.
Secretary of the Auckland branch of the Maritime Union of New Zealand, Russell Mayn, said the announcement had come as a shock to union members.
"We were denied access to attend the meeting as a union so we haven't had time to look over the documentation yet," he said.
"The meeting and the result of the meeting is a surprise to us. For anyone that works down at the port it is crippling news particularly for long serving loyal employees at the port."
Mayn said it was "a given" the union would be fighting the proposal.
"MUNZ is a union that always fights for workers' rights so that they get fair representation so you can take that as a given."
