The southern right whale population in New Zealand is still only around 12 percent of pre-whaling levels, and new research reveals just how close the species came to being wiped out altogether.
An international team of researchers combined historical records from whaling logbooks with modern genetic data, estimating there were around 30,000 southern right whales swimming in New Zealand waters before whalers arrived in the 19th century.
The population dwindled to just 110 by 1925, with only 15 to 20 of those female.
Dr Rochelle Constantine, marine mammal scientist from the University of Auckland, says the main reason why the recovery has been so slow is because they spend their winter months in the waters near remote sub-Antarctic Auckland Island.
"We came very close to losing the southern right whale from New Zealand waters, with at best, only a few hundred remaining after an intense and devastating period of commercial whaling, followed by a brief hunt by Soviet whalers just as the population was beginning to make a comeback."
Southern right whales are increasingly being seen around the New Zealand mainland, most frequently in Southland, but every few years whales are spotted in the Northland region.
"They are vulnerable to being struck by vessels," says Dr Constantine. "A few years ago we had a mother-calf pair and the calf was hit by a small boat that left propeller cuts across its back. These whales will often come close to shore and will approach boats, so it's easy to harass them or injure them."
People are advised to give them room so they can safely swim and hopefully recover to their pre-exploitation population, estimated to be between 29,000 and 47,000 whales.
Dr Will Rayment, Department of Marine Science at the University of Otago, said: "The study reveals just how close the population came to being wiped out altogether. We should be very thankful that a tiny remnant population remained and has slowly been increasing in numbers since the ban on commercial whaling. But we should also be mindful that as the population recovers, southern right whales will increasingly be impacted by human activities."