Whales rediscover New Zealand waters
Southern right whales are back and look to set up New Zealand as a nursery.
That's the view of Auckland University scientist Emma Carroll as research just released shows the whale numbers visiting the mainland have increased considerably over the past decade.
The research was done by the Department of Conservation, Auckland and Otago universities.
It's also likely that at least two females have given birth here, she says, so the shallow waters around New Zealand's coastline may once again become a nursery for these gentle giants.
About 27,000 southern right whales were thought to be living mainly around New Zealand's sub-Antarctic Auckland and Campbell islands before whalers decimated them. They would winter around the New Zealand mainland, especially the South Island, with calves born here. Early visitors complained the noise they made in Wellington harbour would keep them awake at night.
Whaling got under way in this country in the early 1820s.
Southern right whales were so named by early whalers because they are slow moving, float when dead and provided large quantities of valuable oil and whalebone, making them the "right" whales to hunt.
Also hunted in Australia, about 26,000 whales were killed around the two countries, mostly between 1835 and 1844.
By the time they became protected in 1936 they were on the verge of extinction.
There are now about 2000 whales living around Auckland and Campbell islands, with numbers increasing, Dr Carroll says.
But the low numbers don't explain why we didn't see any around the mainland from the 1920s to 1963. The whales tend to stick to the same areas to give birth.
The knowledge that New Zealand was a good place to winter over and calve seems to have been lost to them, Dr Carroll says.
But exploratory trips by single whales seem to have resulted in New Zealand being "rediscovered", she says.
Eleven whales turned up between 1992 and 2002.
Since then females and their calves have also started appearing. Treacherous seas between Auckland Island and New Zealand, and the very young appearance of a couple of the calves suggest they were born in our waters.
A mother with her calf spotted in Golden Bay, Nelson, in 2005 turned up with a different calf in the Mahurangi Harbour and Omaha Bay in 2009.
This followed sightings of three in the Hauraki Gulf, one in Kaipara Harbour in 2004, and one off Whangaparaoa Peninsula the next year, Warkworth Department of Conservation biodiversity ranger David Wilson says.
A juvenile was seen in Bon Accord Harbour, Kawau Island, in 2010, and another cow and calf seen last winter in Omaha Bay, he says.
Identification has come from photographic matching and DNA profiling of skin samples.
Whaling logs suggest the whales may have gone as far north as the Kermadec Islands in the past. But none of the 80 whaling stations were set up north of East Cape, suggesting the whales didn't venture north in big numbers.
The whales may be mating off the south island but there have been more mothers and calf sightings in the north than in the south.
It's early days yet. They may take 20 years to firmly re-establish here, Dr Carroll says.
Even so, she says it raises the intriguing possibility for keen whale watchers that the north could become the preferred nursery in the future.