A study reveals a stark increase in the number of marine mammals stranded in Scotland over the past 30 years. Between 1992 and 2022, 5,147 cetaceans were found dead on Scottish shores, with some species experiencing stranding rates rising as much as 800% annually.
The University of Glasgow’s Scottish Marine Animal Stranding Scheme (Smass) published the paper amidst an unusual series of strandings of deep-diving whale species along northern European coasts. In just over two weeks, 36 beaked and pilot whales were discovered from western and southern Ireland to Orkney, Norfolk, the Netherlands, and southern Sweden. These whales appeared to enter shallow waters, unable to hunt for their usual prey like deep-sea squid.
The widespread occurrence of these strandings has raised alarm, particularly among volunteer groups who attempt to rescue the whales but were unsuccessful in these cases. Dr. Andrew Brownlow, Smass director, noted, “Clusters of beaked whales should raise suspicions.”
It is thought that sonic disturbances may lead deep-diving whales to strand. Rachel Lennon, the study’s lead author, mentioned that Scotland has “abundant” sources of human-made noise, such as seismic survey air guns and industrial drilling. Though the paper does not specifically cite military sonar exercises, in 2018, a globally unprecedented mass stranding of 118 beaked whales in Ireland and western Scotland was traced to a single sound source off the continental shelf, according to Brownlow.
Recently, Smass scientists responded to the strandings of four northern bottlenose whales, another beaked whale species, and a pod of 23 pilot whales in the Orkney Islands. The pilot whale event occurred almost exactly a year after a record 77 of the same species stranded on the same Orkney beach. This year, 150 animals have mass stranded off Scotland.
Additionally, Smass scientists have noticed a significant rise in stranded baleen whales like fin, minke, and humpback, which could be attributed to the northward movement of animals due to warming waters from climate change. The recovery from historic whaling impacts might also explain increased entanglement reports, as noted by Lennon. As surface feeders, baleen whales risk getting caught in fishing gear, suffering prolonged deaths from starvation or infection. The paper highlights a rise in stranded common dolphins and harbor porpoises, often vulnerable to leisure craft collisions.
The 30-year report portrays stranded whales and dolphins as “sentinels,” signaling how human activities impact marine ecosystems. “Clearly, the oceans are changing,” Brownlow said. “Scotland is on the edge of this flux. Sperm whales now calve off our shores, which never happened before. Beaked whales were only seen in small numbers in the autumn. Temperature, salinity, prey distribution, oceanic heatwaves—everything is shifting, and we need to understand these changes better. This is the new normal, and we must tread as softly as we can.”