Circling Sharks:

In Conversation with

The Irish Basking Shark Group


United Nations humanitarian aid workers unload supplies from their vehicle
N K Initials for Niamh Kelly
11th of November 2022

Basking sharks are widely distributed across the world’s oceans, but Irish waters are a hotspot for this seafaring species. The Irish Basking Shark Group (IBSG) is a “network of basking shark researchers” that aims to “combine community engagement, advocacy, and research to advance science-based conservation goals for basking sharks in Ireland”. Alexandra McInturf, IBSG co-coordinator and researcher, and Chelsea Gray, IBSG researcher and science communicator, shared how new research contributes to a better understanding of this elusive species.

Photo by Nigel Motyer courtesy of the Irish Basking Shark Group (IBSG)

“Basking sharks are the world’s second largest fish, and they’re one of three filter feeding shark species, meaning they feed on plankton. Basking sharks can reach over twenty feet [six metres] in length. Otherwise we don’t know a lot about them, because they’re hard to study” Alexandra explained. As a postdoctoral fellow at Oregon State University, Alexandra highlighted the difficulties of researching basking sharks in comparison to many other shark species, “For other shark species, you might attract them to an area by baiting or by fishing, or by chumming. You can’t do that with a shark that feeds on plankton. You also can’t bring them onto the boat to put a tag on them, so tagging them is really challenging”. Multi- disciplinary and innovative approaches to research are required to learn more about basking sharks in Ireland and across the world.

Alexandra’s PhD research focused on basking sharks in Ireland and other parts of the world, including the Pacific. This has given Alexandra “a unique perspective and understanding just how important Ireland is for the species. You don’t see them in the same numbers as you do in Ireland basically anywhere else in the world”. Basking sharks tend to arrive around Ireland in April to feed and begin to leave towards the end of June but could be sighted in Irish waters throughout August. Another possible reason for Ireland being an important habitat for basking sharks is “Ireland is a potential mating ground for them but mating has never been observed in this species so far”.

Basking sharks were recently given the status of “protected wild animal” in Ireland under Wildlife Act 1976 (Protection of Wild Animals) Regulations 2022. IBSG has welcomed this development, but “creating a code of conduct, enforcing a code of conduct and then seeing how we can further protect [basking sharks] remains to be seen”. Alexandra highlighted how “it put Ireland on the global stage” for basking shark conservation. IBSG has continued to research basking sharks in Ireland to gain more knowledge on how to protect the species. Several of the research projects completed or currently being conducted by members of IBSG are explored below.

Sightings Scheme

IBSG runs a sightings scheme that members of the public can contribute to as “citizen scientists” by reporting any sightings of basking sharks around Ireland on the website. Alexandra is “analysing the data from that to try to see if there are environmental factors that tend to bring the sharks to Irish waters” such as the amount of plankton or sea surface temperature. Any correlation between environmental factors and the presence of basking sharks helps to understand how these sharks may react to changes in their habitats. These changes include the possible impact of climate change. As Alexandra explains “what does that mean if the global sea surface temperature is changing with climate change? Should we expect those sharks to move?”

Visual Identification Tags

Alexandra also highlighted Simon Berrow’s (IBSG Co-founder) annual work as he tags basking sharks with visual ID attachments. These visual ID tags are large pieces of plastic with numbers printed onto them. Their large size allows them to be read from a distance away so “anybody can see them and hopefully read the number even if you’re not right next to the shark”. The ID tags allow IBSG to monitor if sharks are returning to Ireland and when they are around. Anyone who sees a basking shark with a tag can report the number to IBSG also. If someone wants to view basking sharks in the water however, safety for people and basking sharks is paramount. Only go out on the water if you have the required skills and experience, and maintain distance from any sharks.

Satellite Tags

Photo by Emmet Johnson courtesy of the Irish Basking Shark Group (IBSG)

Another basking shark research project Alexandra is involved in is SeaMonitor. This project is not directly affiliated with IBSG, but Alexandra is collaborating with other researchers including with Queen’s University Belfast. “They’re putting satellite tags on basking sharks, which are basically tags that can connect with satellites overhead and send a location every time that tag pops out of the water. It’s deployed on the dorsal fins of the shark, so it’s out of the water quite a bit because the sharks feed at the surface” Alexandra explained. The satellite tags allow investigation into the capability of basking sharks to travel long distances. For instance, one shark that was tagged with and IBSG visual ID tag at Malin Head in Donegal and turned up in Cape Cod, Massachusetts a few months later.

IBSG is also interested in the social lives of basking sharks. In a recent research paper, Simon focused on a basking shark behaviour where they gather together, “They just swim around in these massive circles together and that’s called a torus.” The torus could be a potential mating behaviour. Meanwhile, “One thing I’m doing is putting these tags on these sharks that can talk to each other so I can see if certain individuals are constantly detecting the same other ones” mentioned Alexandra, “to try to get a better idea of how they’re interacting in these coastal areas, and whether they actually tend to form groups that stay together. Maybe even travel together afterwards”.

Basking Shark Tourism Survey

Chelsea currently is a PhD candidate in George Mason University and completed her Master’s in environmental science there also. Chelsea’s research during her Master’s focused on why Ireland, particularly Malin Head, had a nearly completely undeveloped basking shark tourism sector, but Scotland, especially the Hebrides, had utilised the presence of basking sharks for tourism. The social science approach Chelsea used included surveying residents of Buncrana and tourists on the beach to learn what they knew about basking sharks. “Most people sort of knew that they didn’t eat seals, and that was basically it. They kind of had an idea that basking sharks were big”, Chelsea discovered during her survey. Many people also expressed an interest in going to view basking sharks either from land or on a boat. Chelsea’s research highlights the importance of raising awareness of less well-known species to ensure their protection.

Individual Based Modelling

Continuing with social science research, Chelsea’s PhD project involves using individual based modelling (IBM) to gather results and to develop a method for how to use IBM results to make recommendations to policymakers. Chelsea explained IBM as complex computer modelling which allows for stochasticity (the quality of lacking any predictable order or plan), or “you have agents like I have little individual sharks. My little individual sharks can interact with the environment and they can impact the environment. Or they can be impacted by the environment”. These agents are not mirroring the behaviour of individual real sharks, but each agent has “has a limited perspective, so it can only see a certain distance and then from there it makes a certain series of decisions”. The limited perspective each agent has reflects that “each individual shark ends up doing its own individual behaviour based on what we call bounded knowledge, so that’s that limitation of how far it can see”, and mirrors real basking shark behaviour. Chelsea compares the results from the IBM to the information IBSG has gathered from the sightings scheme and tagging. The behaviour of individual sharks comes together to form a group behaviour and this is known as “emergent behaviour.

Chelsea is also interviewing Irish policymakers to learn how to best convey IBM results to them. The insights gained from these interviews Chelsea hopes will bridge the gap between “how modelers can communicate their model results to policymakers” and “policymakers are understanding the model correctly and then are applying it correctly”. IBM data can be used to inform conservation legislation through providing insights into how changing environments, locally and globally, may impact on basking shark behaviour.

Basking Shark Conservation

There have been several historical threats to basking sharks. These included fisheries in many places, “there was one off Achill Island which is very famous. It was one of the biggest fisheries in the world, if not the biggest for basking sharks” Alexandra explained, “That whole community has really embraced this part of their history, which I think is amazing. [The community] very much recognize and report when the sharks are around now. And family members of former fishermen have been really active in the conservation of [basking sharks] now”. Another threat was the culling of basking sharks in Canada as “there was an eradication effort because the sharks were becoming entangled in fishing nets”. These are historical rather than current threats, but would have affected the basking shark population.

Current problems for basking sharks are harder to pinpoint as research is still ongoing to learn more about the species. Boat strikes and becoming entangled in fishing equipment may result in a few deaths per year, but the impact of these deaths on the population is unknown as “we don’t know how many sharks there are”. Alexandra also highlighted that “another threat that we would be concerned about is anything that’s going on in the high seas because that it can’t be regulated”.

IBSG is a network of researchers voluntarily working towards educating about, advocating for and protecting basking sharks. The capacity and infrastructure do not exist at the moment for members of the public to volunteer with IBSG, but anyone can participate in the sightings scheme by reporting any basking sharks they see. The benefit of drawing together researchers from multi- disciplinary backgrounds in IBSG is clear to Alexandra and Chelsea. Chelsea sees the importance of cooperation to support basking shark conservation as IBSG “encourage a lot of flexibility and creativity” to spread awareness of basking sharks through different approaches.

 Alexandra highlighted “I think it’s very rare that you get to operate at the intersection of research, policy, advocacy and education. I was able to be not only observing basking sharks in the field and contributing to our knowledge of them this year. But then also getting to be a really active voice in supporting their protection and making a very real policy change”.

Thank you to Alexandra McInturf and Chelsea Gray for their support in this article.


Featured photo of basking shark torus by Simon Berrow, shared courtesy of The Irish Basking Shark Group

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