Southern right whales are flourishing in New Zealand waters, an Otago expert says, and while it is unlikely whales will ever return to Otago Harbour en masse, other areas around the country could be home to growing numbers of mothers and calves.
A southern right whale mother and calf were spotted in Otago Harbour last month and could stay there all winter. University of Otago marine science lecturer Dr Will Rayment said "most years" there were sightings of whales off the coast near Dunedin. Before whaling began, Otago Harbour was a hub for the whales, and Otakou, just inside Taiaroa Head, was once the largest whaling station in the country.
It was unlikely the harbour would ever attract whales and their calves on the same scale as before whaling began, due to the shipping movements around the area and the growth of the human population, Dr Rayment said.
However, it was possible other more remote areas around the country would appeal to mother whales looking for a safe spot, for instance Preservation Inlet in Fiordland.
With exceptions, the southern right whales tended to be "site faithful", returning to the same sheltered spots every three years to raise their young. They came into shore in winter and left for the Southern Ocean again in summer. Dr Rayment has recently returned from three and a-half weeks’ studying the whale population in the Auckland Islands, on research vessel the Polaris II, with a team of researchers and a BBC film crew. Large-scale whaling of southern right whales ended in the 1840s or 1850s, but a few whalers continued to target them. They did not become protected until 1937, and in the 1960s they were illegally targeted by Soviet fishing boats.
The population — slashed from the estimated pre-whale hunting total of about 30,000 in New Zealand waters down to about 100 in the early 19th century — was still slowly recovering. It was difficult to put a figure on whale numbers, but Dr Rayment, who has been travelling to the Auckland Islands to study the whales since 2008, said there were believed to be about 3000 in New Zealand waters. The Otago researchers undertook aerial photogrammetry
and photo identification of the animals, each of which had a unique pattern of callouses, infested with tiny crustaceans called cyamids.
"We can tell they are really happy and healthy," he said.
"They look fat, essentially. They have shiny skin, and they don’t have a lot of scarring."
The whales were "really fun to work with", as they were very curious, approaching the research vessel without fear. Dr Rayment, who studied North Atlantic right whales on the east coast of the United States, said they were in poor condition by comparison, covered in scars from encounters with boats.
The third species of right whale, North Pacific right whales, which lived around Alaska and Russia, were "poorly studied"; it was believed there were only between 300 and 500 left, Dr Rayment said. The Otago research would help scientists working on other populations, giving them a base from which to measure how they were doing.
Today, the greatest hazards posed to the whales — which are known to live for at least 70 years, and could potentially survive for more than 100 years — were "ship strike" and being caught in fishing nets. Orca would pose a danger to whale calves if they came across them, Dr Rayment said. Great white sharks might also prey on right whale calves, but the mother whales "would have something to say" if their calves were attacked.
