Marine mammal strandings—including whales, dolphins, and porpoises—have dramatically increased along Scotland’s coastline over the past three decades, according to a new study by the University of Glasgow. The research, published in Scientific Reports, provides the first detailed analysis of long-term stranding trends in Scottish waters and raises urgent conservation concerns.
A 30-Year Study of Cetacean Strandings
The study examined 5,147 stranded cetaceans recorded between 1992 and 2022 through the Scottish Marine Animal Stranding Scheme (SMASS). Researchers analyzed data across five species groups:
- Harbor porpoises – 2,676 cases (52%)
- Pelagic dolphins – 1,217 cases (24%)
- Common dolphins – 494 cases (10%)
- Baleen whales – 479 cases (9%)
- Deep divers – 281 cases (5%)
Results revealed a clear increase in strandings across all species, but with alarming spikes in common dolphins and baleen whales. These two groups, in particular, showed exponential rises after 2010, with juveniles disproportionately affected.
Regional and Seasonal Stranding Patterns
While strandings occurred across Scotland, researchers identified regional hotspots:
- Harbor porpoises stranded more often along the east coast (Moray Firth, Forth, Tay).
- Baleen whales and common dolphins stranded more frequently along the northwest coast.
- Distinct seasonal patterns were observed across different groups, though no significant differences were found between males and females.
Why Are Strandings Increasing?
The causes of rising strandings are complex, but researchers highlight several human-driven pressures, including:
- Declining fish stocks reducing prey availability
- Bycatch and entanglement from fishing activities
- Noise pollution from ships and offshore industries
- Climate change impacts, such as warming seas and shifting habitats
- Pollution from plastics and chemicals
As whale populations recover from historic whaling, reports of entanglement incidents in baleen whales have also risen sharply.
Scientists Call for Urgent Conservation Efforts
Dr. Andrew Brownlow, Director of SMASS, emphasized that stranded marine mammals act as “sentinels of the ocean”, warning us about changes in marine ecosystems. He explained:
“Rising strandings provide early warning signals that Scotland’s marine environment is under increasing pressure. These findings highlight the need for tailored conservation strategies across different regions.”
Lead author Rachel Lennon, a PhD researcher at the University of Glasgow, added that long-term stranding data is essential for conservation:
“Traditional surveys of live cetaceans are expensive and logistically difficult. Stranding records provide a cost-effective, continuous, and invaluable source of ecological data to guide policy and conservation action.”
Key Takeaways from the Study
- Strandings of common dolphins and baleen whales are increasing at unprecedented rates.
- Juvenile strandings are rising, suggesting young animals are particularly vulnerable.
- Long-term monitoring programs like SMASS are vital for detecting ecological changes.
- Conservation efforts must focus on reducing bycatch, entanglement, and habitat stressors.
Final Thoughts
This groundbreaking study highlights that Scotland’s seas are facing growing ecological pressures. By combining long-term datasets with conservation strategies, scientists hope to safeguard marine mammals and the wider ocean ecosystem.
📖 More information: Read the full study in Scientific Reports