Marine Mammal Strandings

With over 18,500 km of coastline (Scottish Government, 2023), Scotland experiences high numbers of marine animal strandings on its beaches every year. For example, between 1st Jan 2023 and 1st Jan 2024 there were 931 stranding records in the Scottish Marine Animal Stranding Scheme (SMASS) database (SMASS, 2024). 

The bulk of recent strandings around Scotland have been cetacean and pinniped strandings (fig. 1) (SMASS, 2024). Cetaceans are marine mammals who live entirely in the water (i.e. whales, dolphins, porpoises), while pinnipeds are marine mammals adapted to both land and sea (i.e. seals, walruses, sea lions) (NOAA, 2019). A more detailed species breakdown (fig. 2) reveals the most commonly stranded subclasses to be grey seals, harbour porpoises, pelagic delphinids, and harbour seals (SMASS, 2024). 

Along East Grampian Coast the most commonly stranded subclasses are harbour porpoise and grey seal. Harbour porpoises are also common on the South and Southwest coasts, while the grey seal range appears most concentrated along the length of Scotland’s east coast. Pelagic delphinid strandings are more common around the North and West coasts, while harbour seal strandings are concentrated around the Firth of Forth, Moray Firth, and the Firth of Clyde . 

In addition to this mapped data, SMASS (2020) offers stranding data for the 2011-2018 period. As shown in figure 3, this long-term data suggests pinnipeds are the group which strands by far the most often in Scotland. SMASS (2020) also notes a seasonality to strandings, with seal strandings for example increasing during the respective pupping seasons of each species. The overall trend is that of increasing strandings year on year (fig. 4). Only marine turtles and Mysticetes spp. (certain large whale species) show no substantial increase over the 7-year period. 

SMASS highlight that the causes of increasing strandings are highly complex and uncertain. For one thing, the recent increase in public engagement and reporting of strandings has likely contribute significantly to the rising figures (BBC, 2019). That is not to say however that instances of strandings are not increasing. Strandings can be caused by extreme conditions in the oceans, be this wave height, wave intensity or temperature extremes, in addition to anthropogenic inputs like plastics, chemicals and fishing equipment (Brusius, de Souza and Barbieri, 2022). Thus, despite the uncertainty, increasing climate extremes and anthropogenic damage to oceans may also be contributing to the observed strandings increase.

All strandings data was gathered by the Scottish Marine Animal Stranding Scheme (SMASS), part of the University of Glasgow. 

To learn more about Mass Stranding Events in Scotland, please visit our ‘Mass Stranding Events’ page.