"The death of a Lyttelton port worker is the tragic loss of life of another worker and has shaken the maritime industry," he said.
Last Tuesday, Ōtara resident Atiroa Tuaiti died after a "fall from height" while working on a docked Singaporean container ship at the Ports of Auckland.
The Cook Island-born stevedore had a baby boy just a few months old, and his own father Atiroa Snr Tuaiti was working on site at the port at the time of the accident.
Following this accident, unions in the ports and maritime industry called for national stevedoring standards to be introduced to deal with the "health and safety crisis in New Zealand ports".
Harrison said they would continue to campaign "hard" following today's fatality.
"These deaths and serious injuries in the port industry should not be happening, and the controls and processes and culture need to be fixed through national standards," said Harrison.
Three unions in the sector have jointly written to the Minister of Workplace Relations and Safety.
Maritime New Zealand investigators were on their way to the scene this morning.
Rail and Maritime Transport General Secretary Wayne Butson last week said that investigations into the factors that have caused so many deaths and injuries in the stevedoring industry must take place.
Butson said such investigations should include the maritime industry, Government and unions.
"We would expect issues such as hours of work, shift patterns, productivity pressures, training, fatigue, equipment, processes and PCBU responsibilities to be looked at," he said.
"From this process, we would expect an outcome of national standards for stevedoring operations in port health and safety to be developed and introduced in an urgent timeframe."
Following Tuaiti's accident, Butson said it was only a matter of time before another worker's life was taken.