What is it about?
In July 2023, 55 long-finned pilot whales mass stranded on the Scottish Isle of Lewis in the largest such event recorded in Scotland in recent memory. Post-mortem examinations confirmed that the animals were in good health, and subsequent investigations confirmed a combination of biological, behavioural, and environmental factors contributing to the event. Long-finned pilot whales are extremely social animals, and it is likely the group followed a female experiencing a difficult birth into dangerously shallow waters. Using stable isotope analysis - chemical signatures embedded in the tissues of the animals - in a tiny piece of skin, we were able to identify important feeding grounds of the animals: continental shelf edge and slope habitats. In turn, we provided the first direct evidence that long-finned pilot whales use these habitats as important seasonal feeding grounds in UK waters. Understanding feeding habits of large marine predators is critical for the development of conservation strategies, such as area-based management policies.
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Photo by NOAA on Unsplash
Why is it important?
Most cetacean species are extremely difficult to study in the wild, and stranding events like these are often the only opportunity to learn more about a species' ecology. As part of a wider scientific investigation, coupled with multiple other strands of evidence, we were able to decipher important feeding grounds for this data-deficient species. Whilst post-mortem examinations tells us about the animals' condition at the moment of stranding, stable isotope analysis tells us where the animals had been and what they had been eating in the weeks before. Together, they allow us to move from asking what happened at the moment of stranding to asking what set these animals on a course towards it.
Perspectives
Marine mammal strandings capture the public's interest, yet often the causes of these are complex and multifactorial. As oceans change, so do the pressures and problems imposed on marine animals, and assessing the impact of human activities is key to developing effective management strategies to minimise the risk of future events. Using just a tiny bit of skin tissue collected from the amazing responder volunteers and scientists on site that cold summer morning in July, we were able to uncover life before death in these large marine predators. This article proves the power of citizen science and strandings response networks, such as the Scottish Marine Animal Stranding Scheme, in advancing the knowledge base of a poorly understood cetacean species.
Anna Kebke
University of Glasgow
Read the Original
This page is a summary of: The application of stable carbon and nitrogen isotopes to assess the feeding ecology of long-finned pilot whales (Globicephala melas) in Scotland, PLOS One, April 2026, PLOS,
DOI: 10.1371/journal.pone.0346340.
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