Whales seem to be making a comeback in mainland New Zealand - but are we ready to share?
A century and a half has passed since whales longer than a city bus and weighing up to 80 tonnes were regularly spotted in Otago Harbour. The whales once visited each winter to give birth, socialise and breed in the harbour's sheltered waters. Intense exploitation by 19th-century whalers eliminated southern right whales from around New Zealand. But now, after a long absence from our coasts, they may be making a comeback. And that prompts a question: are we ready to again share our coasts with these creatures?
The southern right whale's story is another tragic tale of exploitation through ignorance and greed. Thanks to the demand for baleen-stiffened corsets and whale-oil lamps, the whales were hunted extensively from the beginning of the 19th century. And their downfall was largely the result of their convenient behaviour. They swam slowly and close to shore, floated once harpooned and yielded large quantities of oil, resulting in a reputation as the "right" whale to target.
Intensive whaling saw the population nose-dive from about 27,000 before whaling started to fewer than 100 in 1925. Commercial hunting was abandoned once it was no longer profitable to pursue the increasingly rare whales. Over nearly four decades, between 1927 to 1963, not a single right whale was sighted around the New Zealand mainland, and they were widely believed to be extinct.
But New Zealand right whales' chance of salvation may lie in a cluster of tiny islands in the Southern Ocean 460km south of Bluff. In the mid-1980s, a yacht making a mid-winter visit to the Auckland Islands stumbled across a remarkable sight - up to 100 southern right whales in Port Ross, a sheltered bay on the islands' northern coast.
The Auckland Islands, with a total area about a third that of Stewart Island, interrupt the fierce westerly winds that whip around the high latitudes. Despite their location, the islands are far from desolate and support an incredible diversity of hardy wildlife and plants, many of which occur nowhere else. Seabirds are the islands' most obvious citizens, including albatrosses, penguins and petrels, but there are also many species of land birds and insects as well as seals and sea lions.
Sealers first began visiting the Auckland Islands in 1807 and told tales of the right whales that congregated there every winter. It was their optimistic accounts of rich whaling resources that spurred an ill-fated attempt to establish a British settlement on the main Auckland Island.
By the time the settlers arrived in 1849, open-ocean whaling operations by American and British whalers had already depleted the whales. Disheartened by the lack of whales, the miserable climate and the inability to grow crops in the peaty soil, the settlers abandoned the site less than three years later.
Fast-forward to 1995 and it was scientists who were journeying in search of whales. They found about 900 right whales were spending some of the winter at the Auckland Islands and counted 165 whales inside Port Ross on a single day. It turned out that the sheltered waters of the Auckland Islands were the primary breeding grounds for right whales in the south-west Pacific; the whales were arriving in droves each winter to birth and nurse calves, socialise and mate. However, even after decades of protection, the population was just 5% of what it was before commercial whaling.
What remained unclear was whether the Auckland Islands whales were the source of the right whales appearing occasionally around New Zealand, or whether they were a separate population. From samples of whale skin collected with biopsy darts, scientists from the University of Auckland used genetic analyses to show that whales from the Auckland Islands were the same as the whales showing up around the mainland.
The genetic results also provided insights into how destructive the 19th-century whalers were: the high degree of genetic similarity between the whales indicated the population had been reduced to a few dozen breeding females.
Because whales travel between the two locations, the growing population in the Auckland Islands will probably result in increasing numbers of whales turning up around New Zealand - but are we ready for the return of right whales to our coasts?
Will Rayment, a post-doctoral fellow at the University of Otago's Department of Marine Science, wants to make sure we are.
Rayment is leading a three-year research project, funded by the Foundation for Research, Science and Technology, to find information that could help right whales make a comeback to our coastal waters. This winter, I joined Rayment's expedition team of scientists from the University of Otago, the Department of Conservation and Massey University. The expedition included scientists investigating the winter diet of endangered New Zealand sea lions and hydrocarbon contamination in marine wildlife.
We travelled to the Auckland Islands aboard the University of Otago's research vessel the Polaris II. With my background in marine mammal research, I was excited about the prospects of seeing the rare whales in their natural habitat - a contrast to the specimens and skeletons I usually work with at the Otago Museum.
Museums play a vital role in sharing conservation stories with communities and we see projects such as this as a way to actively increase our knowledge of endangered native species.
I had been told to expect plenty of whales, but as the sun rose on our first morning in Port Ross, I was amazed at what I saw - dozens of right whales lolling and resting on the surface of the harbour. Further out, towers of white water indicated that more of these enormous creatures were breaching, throwing themselves almost clear of the water.
We eagerly launched our two 5m boats and spent the next two and a half weeks zigzagging around Port Ross. Conducting fieldwork within the Furious Fifties in midwinter has its challenges. Having the right safety equipment and keeping within regular radio contact were crucial, as was a midday defrost with a hot lunch aboard the Polaris II. Our fluorescent survival suits made us impervious to the lively but short-lived squalls that regularly march across the Islands.
Manoeuvring the small boats around Port Ross was often demanding, requiring continual awareness of the many mothers and calves as well as the groups of socialising whales churning the water.
It was remarkable how inquisitive they were. They would often approach, at times passing within inches of the stationary boat, manoeuvring their bodies with an awareness and skill that belied their immense size. Back on the Polaris II for the night, we could hear their noisy blows as we lay in our bunks, and the crew were woken by whales rubbing themselves on the anchor chain.
To our research team, a right whale's most useful features are its callosities, the distinctive areas of thickened skin on their massive head and jaw. Callosities are pale-coloured as a result of being infested with lice-like cyamids, which feed on the dead skin. Callosities form unique and lasting patterns, and are a reliable way to identify individual whales when they raise their head above the surface.
With long-lens cameras, we could photograph a whale's callosities at a distance. Such low-impact techniques are important to expedition leader Rayment: "The more we can do to minimise disturbance to this population, the better. That includes thinking carefully about the kind of research techniques we use to study them."
During our time in Port Ross we were the right-whale paparazzi, amassing more than 8000 digital photos from almost 600 encounters. We eavesdropped on the whales, too. Using a series of underwater microphones, we took recordings of the sounds they made: a cacophony of moans, grunts and explosive outbursts.
And although researchers won't be back again until next winter, a solar-powered time-lapse camera will continue to collect photos of a bay where the whales congregate. Ingenious and somewhat experimental, the time-lapse photos will hopefully show Rayment when the whales arrive and leave the breeding grounds.
By combining this year's photos with photos taken on past and future field trips, he will compile a photographic catalogue of the population that will enable him to tell its size and whether it is growing, and also provide a window into the movements of individual whales.
Rayment recently matched a photo of a whale taken by a member of the public at a Dunedin beach with a whale we had photographed in the Auckland Islands just weeks before; this is the first photographic evidence of the link between the Auckland Island whales and the mainland.
The focus of Rayment's research extends beyond the Auckland Islands to pre-empting issues that may arise when southern right whales eventually recolonise New Zealand's coastal waters. "As the population grows we are likely to see more whales around the mainland," he says. "If we can think about the potential conservation problems the whales may face, we could mitigate those impacts."
He believes valuable lessons can be learnt from the problems facing the southern right whale's critically endangered relative in the North Atlantic.
"The major issues are ship strike and entanglement in fishing gear like gill nets and lobster pots. Other potential concerns are modification of coastal habitats through development and aquaculture, and disturbance caused by boat traffic." The shallow and sheltered waters favoured by right whales could also be in demand for human activities.
Around the Auckland Islands, right whales tend to gather in particular areas. Rayment suggests they will choose similar places around the mainland.
By matching the physical features of the areas whales prefer in the Auckland Islands with locations right whales historically inhabited around the mainland, he will try to predict what areas of our coast they will favour. And by providing this information to managers and planners, he hopes they will consider the whales' interests when deciding which activities will be allowed in particular coastal areas.
To some, Rayment's research-based predictions may seem premature - right whales are still a rare sight around the mainland and eventual recolonisation could be an unrealistic dream. However, the return of New Zealand sea lions to Otago indicates that it's not too early to consider such possibilities.
Sea lions were on the verge of extinction by 1830. Maori had all but eliminated them on the mainland and sealers were exploiting them in their last refuge in the Auckland Islands. Fully protected by the late 1800s, the Auckland Islands population gradually recovered and occasional visitors to the mainland were recorded from the 1930s.
In the early 1980s, male New Zealand sea lions began to frequent the Otago Peninsula. A female joined them and, significantly, she remained at Taieri Mouth in 1994 to pup. Now there are more than 10 breeding females on the peninsula, all descendants of that single founding female.
This recovery on the mainland is important, as sea lion numbers are plummeting in the Auckland Islands and the species recently received New Zealand's highest threat classification.
The sea lions' story indicates just how crucial a recovery around the mainland could be for the long-term survival of the right whales.
Since we returned from the Subantarctic, Rayment's task of wading through the thousands of identification photos has been interrupted by calls that right whales have been spotted along Otago's coast. Every whale sighted is another opportunity to make a match with the Auckland Islands' whales, so he is quickly out the door, camera in hand.
Just a few weeks ago, he responded to a report of two right whales in Otago Harbour and captured photos of the whales breaching near the harbour entrance. If the population continues to recover, those photos won't be just a nostalgic flashback to pre-whaling days - but prophetic images of things to come.