Studying Ancient Sharks at the End of the Earth: How Sevengills Are Responding to Climate Change in New Zealand’s Fiordland
SHOW NOTES
Dr Alice Rogers didn’t grow up beside the sea. In fact, she grew up in one of the most landlocked parts of the UK: “The ocean for me as a kid was summer holidays, random summer holidays to the beach, but it wasn’t a big part of daily life” [05:00]. Like many marine scientists, she credits Sir David Attenborough’s programmes with inspiring her curiosity, but it was during her undergraduate degree in Sheffield that she truly found her path.
“I joined the diving club and that was the hook for me… somehow I was like, yep, this is me. This is what I want to do,” Alice recalls [05:55]. Even training in quarries in April and sitting in the snow during dry suit training didn’t put her off; rather, it was the turning point. “If I was going to carry on with my academic career then I would focus it on the marine realm.” Alice went on to pursue a PhD in marine science, one which took her to the Caribbean, where she studied sea urchins. But what she really loved was “understanding how healthy ecosystems work and the dynamics between the different species and organisms in those ecosystems” [08:42]. That focus on community interactions and climate change impacts carried her into her next chapter.
Moving to New Zealand, Alice began working in Fiordland, a vast and remote wilderness at the bottom of the South Island [9.42]. “Fiordland is phenomenal… you go to Fiordland and you’ll see sharks, you’ll see whales, you’ll see penguins and everything in between,” Alice says. With towering peaks and deep fjords, it is “a real true wilderness… very, very different to anywhere else I’ve ever been”. Underwater, it is even more striking: “It really is like a night dive every time you get in… you get these amazing black corals, like huge white trees under the water” [16:56].
But even here, climate change leaves its mark. Local operators, now partners on Alice’s research, noticed unusual seasonal shifts [22.05]. “They’d be like, we never see the sharks at this time of year normally, or the whales are in earlier than they should be,” Alice recalls. Then a major marine heatwave hit, causing a mass mortality of sponges. For Alice, this was a stark reminder that, in even the most remote places, the global threat of climate change is ever-present.
And it was here in Fiordland that broadnose sevengill sharks came to define her work. She describes them as “the dinosaur of the sharks” [25:39] – unchanged since the time of the dinosaurs, with seven gill slits instead of the usual five. To Alice, they seemed like the grandfathers of the shark world, with surprising natures: “They’re like big puppies really. Quite inquisitive… they’ll hang around and check out what we’re doing and keep coming back”. Around fishing boats, the sevengills would come up to the surface of the water “like puppies waiting to be fed” [27:00].
Her SOSF-funded project, ‘Climate Change at the Ends of the Earth’, grew from these encounters [28.29]. The key questions are what the seasonal movements of these sharks are in and out of the fjords, and how that relates to water temperature. Equally, Alice is trying to understand whether these deeper waters might act as some kind of refuge if there was a heatwave event.
To answer these questions, Alice and her team have installed an acoustic receiver array – the first time sevengills have been studied this way in New Zealand [35:07]. The receivers, deployed on steep fjord walls at 10–20 metres, detect tagged sharks passing within 400m, recording their depth and the surrounding water temperature.
Tagging the sharks themselves was a new challenge [42.00]. With the help of shark expert Dr Ross Dwyer, they fished for sevengills and brought them alongside the boat. “When you roll them over, they’re just a bit like puppies. They just tend to just relax… and we’re able to fit them with their tags and then release them,” says Alice. Each shark was also measured, sampled, and fitted with an external ID tag for future recognition.
The project is still in its early stages, but some intriguing patterns are emerging. On the first trip in May, nine of the twelve sharks Alice and her team were able to tag were females, and mostly large females (46:25). By October, however, “we only caught males… mostly large males”. The data so far suggests that the females tend to be more resident in the fjords, whereas males visit for a period of time and then head out somewhere else. Even more exciting, some of the females carried breeding scars – injuries that had occurred during mating – hinting that Fiordland could be an important pupping ground.
For Alice, this work is about more than just sharks. “Things are going to change and they are going to continue to change. A big part of this… is about being prepared for that rather than reacting to it” [50:21]. Top predators like sevengills are important to study because they shape the entire ecosystem: “If we discover that Fiordland is going to be a really important refuge for them in the face of an altered climate, then that’s… something we need to know,” she says.
But despite the challenges, she remains hopeful: “It’s easy to kind of just feel sad and like there’s nothing we can do, but I think there’s lots we can do… our technology and our intelligence is probably going to be our downfall, but also could be our saviour”.
ABOUT OUR GUEST
DR ALICE ROGERS
Alice Rogers grew up in central England, relatively far from the coast, but was always drawn to nature and the sea. She studied zoology as an undergraduate at the University of Sheffield (also far from the sea) and, while studying, learned to scuba dive. For the next four years, she spent most of her weekends and holidays travelling around the country, exploring the UK’s wrecks and reefs.
After graduating, Alice knew that marine biology was her future. She spent the next couple of years gaining skills and experience, diving and volunteering in locations such as Honduras and French Polynesia. In 2011, she completed her PhD at Imperial College London, focusing on the population dynamics of a keystone Caribbean sea urchin, essential for the health of coral reefs. During this time, she gained valuable quantitative skills and discovered her passion for applied science that could inform and improve management.
In 2012, Alice left the UK for the University of Queensland in Brisbane, where she spent five and a half years as part of a leading research group. Her projects took her to the Caribbean and South-East Asia, where she worked on predicting the impacts of climate change on coral reef fisheries and designing spatial management plans to improve outcomes for local communities.
In 2018, Alice moved to Wellington, New Zealand, to take up a permanent position as a lecturer in fisheries science. She now leads the Marine Ecology and Ecosystem Modelling Group, with research spanning both warm and cold waters. Her current work focuses on understanding how climate change and other stressors affect coastal ecosystems, and how management can be improved to ensure these ecosystems survive and thrive for future generations.
