A group of 700 blue whales have been discovered in the South Taranaki Blight, which is due to be the site for seafloor mining operations.
The group are entirely different from whales often found in the Pacific, but they can still reach lengths of 22 metres.
Following a biopsy by Dr Leigh Torres of the Marine Mammal Institute at Oregon State University it was confirmed that the whales were genetically distinct from other blue whales, The Independent reported.
The significance of the discovery is huge, considering the area is about to be home to oil and gas rigs after the seafloor is targeted for mining operations.
Dr Leigh is now working to make sure the whales are not impacted by the extraction.
He told The Independent his team is "working closely with resource managers in New Zealand to help them understand what we do and don't know about this New Zealand blue whale population, so they can apply best management practices to minimise impacts from industry."
Blue whales are usually considered migrant in the region but this new group would suggest that it may actually be a resident population.
Whilst numbers are still being confirmed, it is estimated the exact number of whales is 718.