"Shark Fitbit" Provides First-Ever Data on Basking Shark Response to Boat Strike

In a groundbreaking study, a collaborative team fitted a "shark fitbit" with an integrated camera to a 7-metre female basking shark in County Kerry, Ireland. The device, scientifically known as an “animal-borne camera and inertial measurement unit,” aimed to gather crucial behavioural and physiological data on the species. Merely six hours post-attachment, the shark was struck by a boat in Ireland’s newly designated National Marine Park.

Data retrieved from the shark fitbit revealed that the basking shark immediately swam to the seafloor, moved to deeper offshore waters, and exhibited significantly reduced activity levels following the strike. The device released itself approximately seven hours later, showing that the shark had not resumed normal behaviour. Although the initial impact was non-lethal, researchers remain uncertain about the extent of internal injuries and the shark's ultimate survival.

The findings, recently published in the journal Frontiers in Marine Science, underscore the urgent need for a legally binding boating conduct code, including vessel speed restrictions in basking shark aggregation areas, with enforcement power for appropriate authorities. In the interim, boaters are advised to reduce speed to less than 6 knots in areas where basking sharks are known to surface. The Irish Whale and Dolphin Group provides sightings report updates during sunny, calm days in spring and summer, offering guidance to boaters.

For more detailed instructions on interacting with basking sharks, the Irish Basking Shark Group’s Code of Conduct is available on their website.

Nick Payne, Assistant Professor in Trinity College Dublin’s School of Natural Sciences, commented, “Ireland remains one of the few places worldwide where globally endangered basking sharks aggregate in large numbers. It is fantastic that they were protected under the Wildlife Act (1976) in 2022, and this year, the government announced Ireland’s first National Marine Park off County Kerry, frequented by the species for feeding and likely breeding.

“However, the fact that a shark fitted with our ‘fitbit’ was struck within a few hours in this area highlights their vulnerability to boats and the need for greater education on mitigating such strikes. Basking sharks filter feed at the surface, similar to some whales, making them equally susceptible to strikes.”

Alexandra McInturf, Research Associate at the Coastal Oregon Marine Experiment Station (COMES), Oregon State University, and co-coordinator of the Irish Basking Shark Group, views this incident as an impetus for further research on interactions between water users and basking sharks in Ireland. She stated, “This incident indicates the need for more research on ship strike prevalence on basking sharks in the new National Marine Park and other hotspots along the Irish coastline.

“It also raises questions about how often sharks occupy these habitats when not visible at the surface. Given Ireland’s unique position as a persistent habitat for basking sharks, addressing these questions is critical for both our ecological understanding and conservation of this endangered species.”

Taylor Chapple, Assistant Professor at COMES, Oregon State University, and lead author, added, “Unlike whales, basking sharks often sink when killed, making it hard to gauge mortality rates. Even in this case, where the strike wasn’t immediately lethal, we are unsure of the fate of the female that was hit.

“The overlap between sharks, whales, and other marine life with maritime activities is a global concern. Non-lethal effects of strikes can also have significant short- and long-term consequences, which are even more critical when they affect endangered species we strive to protect.”

This research was funded by Future Legend Films, Oregon State University, National Geographic, and the Human Frontiers Science Project.