Mass whale strandings are relatively common in New Zealand, but we don't yet know enough about what happens to the marine mammals when we intervene, says expert Dr Karen Stockin.
More than 600 pilot whales beached at Farewell Spit in February 2017 in mainland New Zealand's largest recorded stranding. Photo: AFP / Marty Melville
Whale strandings on New Zealand shores – mainly pilot whales, plus a smaller number of pygmy whales and false killer whales – have been recorded since the 1800s.
Though there’s no doubt that some strandings, internationally, are caused by human activity, such as naval sonar testing and seismic surveys, many took place before these technologies were in use, Stockin says.
Strandings are most common on gently sloped beaches where tides go in and out very quickly, such as Farewell Spit in Golden Bay.
In February 2017, more than 600 pilot whales beached there in the largest New Zealand mainland stranding since records began.
Until now, New Zealand research has focused on why whales end up on our beaches, says Dr Stockin, a director at Massey University's Marine Research Group.
Less attention has been paid to identifying which whales can survive refloating and which shouldn't be put back to sea.
Once beached on land, whales quickly overheat and – out of the buoyancy of water – their massive body weight causes internal injury, she says.
Whale society is matriarchal, and often female adults are the first to be refloated, in the hope they’ll draw the rest out to sea.
Dr Stockin's team is looking closely at other aspects of leadership in whales pods, and testing whether more vocal whales turn out to be leaders when put back to sea.
The aim is to save as many beached whales as possible and it’s equally necessary to identify those whose chances of survival are limited, she says.
“There isn’t anybody on a New Zealand beach at any time who wants to be … pushing animals back to sea if they’re not going to survive.”
Dr Karen Stockin Photo: Supplied
Some indicators are clear – an animal with broken pectoral flippers shouldn’t be refloated because it won’t be able to forage or feed, and would suffer a slow and lingering death.
Even whales that appear healthy as they swim away from shore can succumb to a phenomenon known as 'capture myopathy' in which the stress of being moved and lifted leads to fatal internal damage, Stockin says.
A project is underway to find ways of identifying which beached whales are under such severe stress, which includes testing cortisol levels and tracking whether that correlates with how long they live.
The human impact at a whale stranding is significant, Stockin says, so it's important that people on site be given a clear explanation of animal welfare and why a whale may have to be euthanised.
More than 1000 people responded to the 2017 Farewell Spit beaching, many who had no previous experience of a whale stranding.
The group interacted with and formed bonds with the sea mammals over six days.
“You were dealing with, in many cases, people from all corners of the world who may have only just rocked up to New Zealand a matter of hours before, heard about the event, and were literally in Golden Bay within hours.
“In the work that the stranding network does with Project Jonah, with their roadshows, with their training of medics …it does mean there’s a good level of education being put out to the New Zealand public.”
Stockin says the prospect of tracking the survival of refloated whales, using methods such as tagging, has received support from iwi elders and the public of Golden Bay.
Dr Karen Stockin is one of 25 international experts advising the International Whaling Commission on strandings and a scientific advisor to the charity Project Jonah.
