On the hunt for basking sharks in the Inner Hebrides, Scotland

Scotland is famous for many things – gorgeous scenery, whiskey, bad weather, Loch Ness, kilts – but less so for its status as a global hotspot for the planet’s second-largest fish.

The basking shark can grow up to 11 metres long, ceding the gold medal only to the tropical-dwelling, much more famous whale shark. Every summer, groups of basking sharks convene in the deep channels of cold water flowing near the Hebrides islands, attracted by large concentrations of their favourite food: plankton.

Yes, that’s right – like whale sharks and baleen whales (whales such as blues, minkes, and humpbacks which filter the water for food using curtain-like strips in their mouths instead of teeth), these gentle giants feed almost exclusively on microscopic organisms. While not technically herbivores, since basking sharks don’t distinguish between zooplankton (tiny shrimp-like animals) and phytoplankton (tiny plants), you certainly won’t find a basking shark trying to eat any other sea creature visible to the naked eye.

A basking shark. Image via Yohancha at Flickr

To a lay person, it initially seems baffling that the planet’s largest creatures are nourished by some of its smallest. How can a basking shark possibly eat enough plankton (or krill, in the case of the whales) to grow to such an enormous size – and thrive?

To understand it, you have to go back to high school biology, and the idea of the “food chain.” There’s a really good longer explanation here, but essentially, at the lower “rungs” of the food chain, there is an abundance of energy contained within the billions of smaller creatures and plants (on land, think of the ubiquity of grass or insects). And every time that energy base is eaten and processed by creatures above it in the food chain – say, fish eating plankton or mice eating grass – most of its initial energy is lost. So, it actually makes way more sense for a creature as large as the basking shark to skip the rungs directly beneath it and to go straight to the source of maximum energy: the tiny creatures and plants at the bottom of the food chain, which are plentiful enough to sustain its massive size. However, this means that it needs to be eating almost constantly, or trying to – hence its mouth being almost always open, to capitalise on every opportunity to filter some plankton into its stomach.

(As a side note, this is why feeding plants to cows and other farm animals for human consumption is grossly inefficient, and not scalable for billions of people without destroying the planet – and why a plant-based diet is so aspirational in the alternative protein movement.)

World data, 1856 – 2019. Source: Ocean Biodiversity Information System. Map by S. Petersen.
The Hebrides.

It turns out that Scotland – specifically, the isles of the Inner Hebrides, like Soay, Mull, and Coll – are some of the places where basking sharks can be most reliably spotted during the high summer season (July to September). Their numbers were once so abundant that they were hunted in the 17th, 18th, 19th and 20th centuries for their large oily livers, which could weigh up to a tonne, much as whales were hunted for their blubber. Immortalised in the book Harpoon at a Venture by Gavin Maxwell (1952), who went on to become a famous naturalist, this practice was astonishingly not outlawed until 1994. From then on basking sharks became a protected species, and the process of hunting them took on a different flavour: tourists armed with cameras, rather than harpoons, now crowd onto boats for a chance to shoot the shark.

Basking sharks remain fairly mysterious. Research on them is emerging all the time, but little is known about where they spend the winter months, how they breed, and what their overall numbers are like. One satellite tag recently revealed that a single shark had crossed the entire Atlantic ocean during one northern hemisphere winter, but beyond that it’s hard to say. Satellite tagging has only limited usefulness, because the tracking devices only communicate information when they’re at the surface. If the shark dives deeper, their location cannot be tracked.

The basking shark, then, is actually quite an elusive creature, spending only roughly 10 per cent of its time feeding at the surface. Drawn by the possibility of seeing one nonetheless, and being interested in whaling and the history of energy consumption in northern Europe, my friend and fellow researcher Miriam Sentler and I made Covid-proof plans to focus on the basking shark during an artistic residency at KNOCKvologan, a wonderful space run by two very kind Dutch artists. My thesis work at Research Master level prepared me well for the possibility of the non-encounter – I have spent the past two years researching the Greenland shark, which I have never seen, do not have the means to see, and probably therefore never will see. What’s more, very little is known about the Greenland shark, though marine biologists are publishing new papers all the time. The question which underlined my whole thesis was: how should we study such a creature? What can we meaningfully say about something so unknown?

Excitedly planning my excursion, accompanied by artist, researcher, and good friend of mine, Miriam Sentler.

These questions emerged again in our own hunt for the basking shark. Unlike the Greenland shark, though, the basking shark is tantalising because it feels feasible. When I asked for a show of hands at our public presentation about our trip on Mull, over half in attendance had seen one. It is commonplace for long-term residents of these isles to share stories about seeing the shark, sometimes even in densely packed, swirling columns known as “shark wheels.” And the tour company we went with seems to think that in high season, chances are pretty good.

Anecdotally, this adds up to a lot of shark sightings. Yet it takes a significant time investment to ride out seasonal fluctuations in shark appearances. In practice, that means a lot of these encounters with sharks alternated with years of seeing nothing: what you really need is a hefty dose of good luck to find sharks during the small window of time that you happen to be on the islands.

Our three-day excursion began on a boat on the isle of Coll. Packed into a small boat, we and our lovely tour group set out with Basking Shark Scotland to try our luck. Groggy with seasickness tablets Stugeron 15, it was harder than it sounds to stare out at the horizon in search of a dark dorsal fin for up to seven hours at a time – and having started out in the highest of spirits, many of us had nodded off by the time the afternoon rolled around.

Miriam with tour guide and bird expert Jack: “Is it a fin?!”

It became apparent about halfway through the trip that our chances were not looking good. Apart from the odd cheeky seal and scores of gannets, we didn’t really see any wildlife at all. We did, however, have some absolutely lovely snorkels in drysuits, where the clearness of the water was astonishing and some sweet grey seals watched us from ten metres away. Aside from that, the sea’s surface remained stubbornly devoid of shark fins. So where were they all?

In search of answers, one day we visited Professor Clive Fox at the Scottish Association for Marine Science (SAMS), near the town of Oban which, along with Mallaig, is one of the main ferry hubs for visitors heading out to the Inner Hebrides. Showing us some plankton under a microscope in his lab, Professor Fox told us that plankton is difficult to study in real time, but that a “late” bloom this year was a possible cause for the basking sharks’ absence. (I say this in inverted commas because referring to natural fluctuations as “early” or “late” arguably only really makes sense when we expect nature to follow human schedules.)

In her work on dance and rhythm in Victoria River, Australia, anthropologist Deborah Bird Rose develops what Stuart Cooke calls “a poetics of absence” as a way of conceptualising those times when we cannot see that which we wish to see:

Living things communicate by their sounds, their smells, their actions, the stinging bite of the march fly, the sight of flowers floating on the water. They also communicate by their non-presence. Events that occur to the same rhythm require intervals of non-occurrence. There are times when things do not happen, and it is the not-happening that makes it possible for the happening to have meaning.

Deborah Bird Rose, “To Dance with Time: A Victoria River Aboriginal Study.” The Australian Journal of Anthropology, vol. 11, no. 3, 2000, pp. 287-96. Quoted in Stuart Cooke, “The Ecological Poetics of Deborah Bird Rose.” Swamphen, vol. 7, 2020, openjournals.library.sydney.edu.au/index.php/Swamphen/article/download/14365/pdf.

Following Rose, absence (or non-presence) is here treated as a provocation rather than something to avoid. Such a framing applied to the basking shark precipitates a shift towards viewing its non-presence in worlds habitable to humans as evidence of its agentic capabilities. In other words: the basking sharks were withholding themselves from view. They didn’t care to be found.

Visiting Professor Clive Fox and catching plankton at the pontoon at SAMS, just outside Oban.
Giving our public talk at the amazing project that is KNOCKvologan.

Miriam and I spent three weeks in the Inner Hebrides, including our beautiful stay at KNOCKvologan on the Isle of Mull, which is where we gave our public presentation about our hunt for basking sharks. When not searching for the sharks, we were out enjoying the islands. The sun gods were smiling on us somehow. The beaches in the Knockvologan area were transformed into a tropical paradise, replete with the clear blue hues and white sands one would expect of those latitudes. Sheep panted in what little shade they could find; horseflies disturbed the peace, making lazy attempts to bite. We ran into the shallow waters – still a crisp 11 degrees Celsius – and dipped our shoulders under to escape them. Otherwise, we basked on hot rocks to the sounds of juvenile sheep cropping the grass around us.

Iona Abbey

One day, we visited Iona, famed as the place where Christianity reached Scotland. The squat stone Iona Abbey sits on foundations of a sixth century monastery, and looks out over the narrow blue strait separating Iona from Mull. We walked to the strand of the monastery, or “monk beach”, another stretch of white sand lapped at by prickly cold waters in various shades of turquoise. We peeled off our clothes and waded in, feeling the hairs on my skin stand to attention as the cold spread upwards throughout my body. Snorkel in hand, I timidly placed rather than plunged my face under the surface, seeing where thick fronds of kelp darken the shallows.

We also got to see an adorable colony of puffins – the absolute highlight of the trip.

We could get up really close to them as long as we didn’t lie on their burrows, in which puffin babies (pufflings!) were hiding. In a nice twist on the usual story of humans messing everything up for a beloved wild species, the presence of tourists enamoured of the puffins actually helps them out by scaring off predatory birds like gulls and skuas.

We never did see a basking shark. By not showing itself, we couldn’t help feeling that the basking shark was, in some small way, reversing the many years of exploitation its species had experienced at human hands, and which we read about in our books. Once sneered at by hunters like Gavin Maxwell as slow and stupid, the basking shark had proven it was perfectly capable of avoiding us. By withholding itself from human scrutiny, even of the “environmentally conscious tourist” variety, it seemed to be saying: I cannot be bought.

The route taken by our boat across three days, searching for sharks. With thanks to Cameron at Coastal Connections, Oban, for the information.

📚 Reading list

Books

  • Colin Speedie – A Sea Monster’s Tale: In Search of the Basking Shark (2017)
  • Tex Geddes – Hebridean Sharker (1960)
  • Gavin Maxwell – Harpoon at a Venture (1952)
  • Jules Verne – Twenty Thousand Miles Under the Sea (1870)
  • Morten A. Strøksnes – Shark Drunk (2015)

Academic books + articles

  • Martin McGonigle – “Oil and Water—18th-Century Whale and Basking-Shark Fisheries of Donegal Bay, Ireland” (2008)
  • Andreas Malm – How to Blow Up a Pipeline (2020)
  • Jennifer Wenzel – The Disposition of Nature: Environmental Crisis and World Literature (2019)
  • Stephanie LeMenager – Living Oil: Petroleum Culture in the American Century (2013)
  • Cara New Daggett: The Birth of Energy (2019)
  • Andreas Malm – Fossil Capital (2016)
  • Denis Fairfax – The Basking Shark in Scotland (1998)

Podcasts

Project website: https://insidetheshark.wordpress.com/.

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