Scientists probe increase in whale and dolphin strandings in Scotland

Volunteers successfully removed ropes from a whale that was stuck on Raasay island.

A study by the University of Glasgow revealed a significant increase in marine mammal strandings in Scottish waters. The number of stranded whales, dolphins, and porpoises has surged from about 100 per year to over 300 in the past 30 years. Possible causes cited by researchers include pollution from chemicals, plastics, and noise, as well as accidental entanglements in fishing equipment.

Between 1992 and 2022, more than 5,140 stranded marine animals were documented. Strandings occur when marine animals become trapped in shallow waters or on shorelines, often resulting in death or injury.

The research, published in Scientific Reports, noted a notable rise in strandings involving common dolphins and baleen whales, such as minke and humpback whales. Data for the study was collected by the Scottish Marine Animal Stranding Scheme (SMASS).

Harbour porpoises made up over half of all strandings at 2,676 cases, followed by pelagic dolphins with 1,217 incidents. The study recorded a total of 494 common dolphins and 479 baleen whales stranded over the 30-year period.

Scientists highlighted a steady increase in strandings involving deep divers like sperm whales and pelagic dolphins since the 1990s. They suggested that human activities, including declining fish stocks, noise pollution, and entanglements with fishing gear, were likely impacting marine wildlife.

Initiatives like the Scottish Entanglement Alliance (Sea) have been established to address the threat of entanglements. This coalition aims to develop best practices to prevent entanglements and respond effectively to such incidents.

Dr. Andrew Brownlow from SMASS emphasized the importance of public reports of stranded marine animals in understanding the health of the oceans. He noted that these animals serve as indicators of changes in the marine environment and increasing strandings could signal broader issues.

Dr. Brownlow stressed the need for tailored mitigation strategies to address unique threats faced by different regions. By identifying when and where species are most vulnerable, targeted monitoring and conservation efforts can be implemented to protect marine ecosystems effectively.