environment

Whales, dolphins, and the Hauraki Gulf

A champion of marine mammals, Dr Rochelle Constantine is making new strides in tracking the intriguing journey of Oceania’s humpback whales, and understanding the sounds and smells of the Hauraki Gulf.

What does the Hauraki Gulf smell like? How are cats killing Māui dolphins? And why do mother and calf humpback whales congregate in Antarctica’s Ross Sea region?

That’s a mere slice of the conundrums Dr Rochelle Constantine, a champion of the marine environment, wants to find scientific answers for.

One of the country’s most distinguished marine ecologists, Constantine has been recognised as this year’s winner of the Sir Peter Blake Trust environment award for her ongoing work in marine research and conservation.

An associate professor in the University of Auckland's School of Biological Sciences and Institute of Marine Science, Constantine says her current projects are too numerous to list. But at the heart of them all is the health and future of our marine life.

Renowned for her work with cetaceans - marine mammals including dolphins and whales - and her key role in the South Pacific Whale Research Consortium, Constantine is making inroads into mapping the journey of the humpback whales of Oceania. She’s been studying these ocean giants for the past 24 years.

In March, she spent six weeks in Antarctica on board NIWA’s flagship research vessel Tangaroa, following whales in the new Ross Sea Marine Protected Area. Constantine and the university’s “Whale Team” were among 23 scientists working on atmospheric, oceanography, ecology and biology projects in Antarctic waters.

Back in 2015, Constantine led a group of scientists to Raoul Island in the Kermadecs, where they tagged 25 humpbacks and collected tissue samples to gather valuable genetic information about who the whales were, and where they’d come from.

Scientists knew that Raoul was a habitual pitstop on the whales’ journey south each year. But what they didn’t know was where the whales then went to feed in Antarctic waters.

Constantine’s latest trip to Antarctica was to look for the whales and map the fields where they dine.

“We used underwater acoustics to get a picture of where krill and fish aggregations are, and we’ll overlay that information on where we are finding the whales. Are they randomly distributed through Antarctica, or are they associated with particular locations, prey type or sea temperature?” she says.

One of the most interesting discoveries was finding male humpbacks and females without calves headed to the Bellingshausen and Amundsen seas to the west of the Antarctic peninsula, while females with calves headed straight to the eastern Ross Sea region.

“There were more mother-calf pairs than we would expect by chance,” she says. “It confirms what our tag studies had shown, and what historical whaling showed – that they caught more mother-calf pairs there.”

“We’re interested to see whether those kinds of movement patterns persist.”

Now she’s working on returning to Raoul, to tag the whales again. “We actually gathered more data about the whales in Antarctica from the Kermadecs. The Antarctica data are useful, but it was much more challenging,” she says.

Constantine is famous for her successful work to slow down traffic in the Hauraki Gulf, to help the survival of Bryde’s whales susceptible to ship-strike.

She is now contemplating the next steps for Sea Change - Tai Timu Tai Pari, the new marine spatial plan for the Hauraki Gulf.

Constantine’s main concern is for the marine megafauna – birds, whales, dolphins, sharks and their prey – that live in the 1.2 million hectare marine park.

“For the megafauna, the whole gulf is important,” she says. “We want to know how we can better understand the large animals, and work out how we can survey the Gulf more efficiently.”

“I have a student finishing her PhD who’s shown rather than the Gulf only being important spatially, it’s important temporally. So the time of year is very important. What we’re seeing in the warm water months is quite different than the cold water months. That’s a really new way for humans to think about how we manage and protect space.”

Constantine is investigating using large drones to survey the gulf from above, but also chemosensory and acoustic tools, “to understand how the Gulf smells and sounds,” she says.

“We’re working with acousticians and chemical ecologists, to bring together multiple layers of research tools that can help us think about the Gulf in a different way.”

The threat management plan for Hector’s and Māui dolphins is also a priority in Constantine’s work. She was part of the research team who showed the government that the Māui dolphin was more critically endangered than believed, resulting in increased protection for the species.

“We’ve done a lot of work around the genetics and population modelling of these dolphins. Hector’s are now doing quite well, broadly speaking. But Māui dolphins are still deeply in trouble,” she says.

“A healthy male Māui dolphin was bitten by a shark and died earlier this year. Those natural events are a real challenge.”

“Another emerging threat is toxoplasmosis through cat faeces. Of the last four Māui found dead, two had toxoplasmosis. It’s a challenging thing for the pathologists to find out how it is reaching the dolphins, especially when you only have around 60 animals left.”

Constantine sees the environment award from the Sir Peter Blake Trust as an acknowledgement of all the people who have worked on marine protection projects with her.

“I guess I don’t think of myself as a leader. I often describe myself as a conductor of orchestras,” she says.

“I like thinking about all of these conundrums and wicked problems. And so many are solved by people working together.”

“I’m quite comfortable with uncertainty – I’m someone who doesn’t mind not knowing. I’m quite happy to have an idea that doesn’t work out, and revisit it in a couple of years’ time. The answers don’t often come quickly.”

It was the first time since 2005 that recognition was bestowed on a leader working in the environmental field at the Sir Peter Blake Leadership Awards. The chief executive of the Sir Peter Blake Trust, James Gibson, said Constantine shared Sir Peter’s passion for raising awareness of the issues the marine environment is facing.

“Rochelle does this by being an effective science communicator of uncommon clarity, accessibility and influence,” he says. “We look forward to seeing her further leadership contribution in the environmental space in the years to come.”

*The Sir Peter Blake Trust inspires and mobilises the next generation of Kiwi leaders, adventurers and environmentalists, by delivering programmes and experiences that continue Sir Peter’s legacy of leadership and environmental action.

Find out more about the Trust here.