Auckland University has begun a study to try to reduce the number of Bryde's whales being killed by ships in the Hauraki Gulf.
The Gulf and the Port of Auckland are the main habitat of the whales.
Researcher Rochelle Constantine says 45 whales have been killed over the past 20 years; 90% of them were struck by ships.
The whales will be fitted with sensor, video and audio equipment, which will allow researchers to see for the first time what the mammals do when they' are below the surface.
The data will be used to determine when the species is at its most vulnerable, so ships in the area know when they need to take the most care.
Ms Constantine told Sunday Morning that monitoring equipment is attached to the whales for roughly 19 hours. The first sensor was attached on Monday.