An independent environmental consultant will have the power to stop or delay SailGP races if endangered dolphins are sighted too close to the boats in Whakaraupō Lyttelton Harbour.
A Marine Mammal Management Plan (MMMP) has been released for the global event on 23 and 24 March, designed to prevent the boats from colliding with mammals including Hector's dolphins.
It has been developed by SailGP together with Te Hapū o Ngāti Wheke and the Department of Conservation (DOC).
It sets out the processes to follow if mammals are seen approaching or inside the event's boundaries, where they could potentially come into the path of the F50 foils travelling up to 100km/h.
Officials said the MMMP had been revised since last year's event based on lessons learned.
Key changes included the appointment of an independent decision-maker who had the power to instruct for a race to be halted or delayed if a dolphin was seen in the designated shutdown zone. Jared Pettersson, director of environmental consultancy Enviser Ltd and the lead author of the MMMP, had been appointed to this role.
The plan said a 300m extension of the shutdown zone had been included around the full perimeter of the racecourse boundary "to ensure boats travelling above five knots (9.2km/h) do not come within 300 metres of a marine mammal".
It said the number of on-land and on-water observers had also increased.
SailGP managing director Andrew Thompson said this year's plan built on robust measures which worked well in the previous season, as well as what officials know now about delivering events in the unique marine environment.
"Last year's event delivered significant benefits regionally and nationally - from driving millions in visitor spend, to providing an enduring legacy for the local community. We look forward to staging another fantastic showcase on Lyttelton Harbour in the coming weeks," he said.
Mishele Radford, chairperson of Te Hapū o Ngāti Wheke, Rāpaki said the successful implementation of the revised MMMP was critical for the safety of all marine mammals, and ultimately the success of SailGP 2024.
A DOC memo obtained by RNZ revealed there was an incident during the event's final race in 2023, where two dolphins crossed the boundary into the race zone as the racing boats approached the final marker.
It is illegal to harm, harass, injure or kill marine mammals in New Zealand, and by law, vessels can travel no faster than five knots when within 300 metres of a marine mammal.