WaterSafe Auckland says a traditional Pacific Island fishing method is dangerous in New Zealand waters because of the powerful surf.
The warning follows the deaths of three men who were net fishing north of Port Waikato on Labour Day and the disappearance of a man in Manukau Harbour on Saturday night.
WaterSafe Auckland chief executive Sandy Harrop says net fishing is popular in the Pacific Islands where people often fish in lagoons with little or no surf.
However she says it is a different story in New Zealand where net fishing can be far more dangerous and people can be swept away.
Ms Harrop says it is vital that fishers avoid dangerous areas and wear lifejackets to protect themselves.
She says her organisation is working to educate people, especially from the Pacific community, about the dangers of net fishing in New Zealand.