Reports from the public of tohorā off the New Zealand coast are for a new study by the University of Auckland, the University of Otago and DOC to investigate the genetic makeup and track the population growth of southern right whales.
Tohorā were driven almost to extinction by whaling in the 19th and 20th centuries. By the 1920s, they had disappeared from the waters around New Zealand with just a small population of 30-40 breeding females remaining in the remote sub-Antarctic islands.
But after decades of protection, they are making a steady comeback with population growth estimated at up to 7% per year. Latest estimates put the total population at around 2000 animals which means a higher chance of spotting one and a higher chance that when whales do visit, they will stay for longer.
Sightings of tohorā begin around Matariki in June and are possible almost anywhere during the winter months from Southland to Northland.
“As the visit by the Matariki whale in Wellington showed, southern right whales are being sighted more often and that gives us the opportunity to find out much more about them,” says University of Auckland marine researcher Dr Emma Carroll.
“We are particularly interested in sightings of mother-calf pairs around mainland New Zealand because that could mean the whales are once again returning to breed here.”
Another study aim is to compare genetic data of whales seen near New Zealand to those in the subantarctic.
“Learning more about where tohorā are found near our coast will help us manage threats to the whales as they return to visit our busy shores,” says Hannah Hendriks, DOC Marine Species Support Officer.
Anyone seeing tohorā is asked to call DOC’s hotline 0800 DOCHOT/0800 36 24 68 as soon as they can and, if possible, take photos and send them to DOC. DOC staff will then endeavour to get photos and collect skin samples for genetic analysis.
People are asked to abide by marine mammal regulations if a whale is spotted, including keeping a distance of at least 50m away or 200m if a calf is present. Vessels should be no closer than 300m, including vessels such as kayaks and paddleboards, and drones should fly no closer than 150m horizontally above any animal.
Large and slow-moving, southern right whales are mostly black in colour and easily identified by white growths on their heads called callosities. They have no dorsal fin and a V-shaped blowhole spray. Adults average 14m-15m in length and newborn calves between 4.5m and 6m.
“Asking the public to report sightings is a great example of how New Zealanders can really help with a scientific study because the more information we have, the better we will be able to answer questions about the recovery of this taonga species,” says Dr Will Rayment from the University of Otago’s Department of Marine Science.
The study is supported by a Rutherford Discovery Fellowship from the Royal Society of New Zealand Te Apārangi.
- DOC is also asking people to keep a lookout for a humpback whale entangled in fishing line that was seen off the bottom of the South Island on Saturday, 22 June. Anyone who sees the entangled whale is asked to report the sighting to the DOC hotline 0800 DOCHOT/0800 36 24 68. The humpback whale could be travelling up the east or west coast of the South Island in coming days.