Stevedore and father of two Atiroa Tuaiti, 26, fell to his death while working on a ship at the Ports of Auckland last Tuesday. His father was working there when the tragedy happened.
Council of Trade Unions president Richard Wagstaff said the Lyttelton worker's death reinforced calls for an inquiry, from which national standards could be developed.
"Every worker deserves to know that when they go to work in the morning, that they will be coming home safely at the end of the day. Sadly that is not the case in this industry, and urgent action is needed," he said.
Maritime Union national secretary Craig Harrison said the deaths were preventable.
"We've got a terrible record in the industry in the past few years.
"It's not a big industry, and if you compare us to the Australian steel and mining industries, which have far greater volumes and not anywhere the fatalities or harm we seem to be facing."
Workplace Relations and Safety Minister Michael Wood last week said he did not accept workplace deaths were inevitable. He has not ruled out a national inquiry into injuries and deaths at New Zealand ports and told RNZ he would consider a union proposal.
"While it is too early to determine what has occurred, I know people will be rightly concerned about the safety culture at our country's ports," he said.
"Two incidents in a week is unacceptable and in the coming days I will confirm what further steps the government will take to minimise future harm at our ports."
Lyttelton Port Company acting chief executive Kirstie Gardener said the company could not give any more details about the death.
"I wish to express my deep sadness and condolences to both the family of our team member and to the rest of the LPC team," she said.
"Our focus right now is on supporting our staff and the family of our LPC team member at this tragic time."