Insights from the first dedicated Fair Isle sandeel survey published

UHI Shetland, in partnership with the Fair Isle Demonstration and Research Marine Protected Area (DR MPA) Executive Steering Group, have released a report which describes the results of the first detailed assessment of sandeel populations around Fair Isle offering valuable insight into a species that plays a vital role in the island’s marine ecosystem and seabird populations.

Sandeel populations are an important feature of Fair Isle’s seas recognised by the DR MPA designation order and highlighted as a high priority research area following community and stakeholder consultation in 2020//2021. Sandeel are vital in supporting marine ecosystems, making up an important component of the diet for many marine species, including, commercial fish and marine mammals.

As a principal prey species, sandeel are of great importance to the globally significant Fair Isle seabird populations particularly during the breeding season. The 2025 Fair Isle sandeel survey focused on traditional fishing grounds to the east and west of the island using trawl methodology, Baited Remote Underwater Video (BRUV) and sediment sampling to assess the species composition, size structure and spatial distribution of sandeels around Fair Isle.

Catch results show four species of sandeel observed on sandbanks close to Fair Isle during the 2025 survey. These include (in order of abundance) smooth sandeel, Raitt’s sandeel, great sandeel, and a small catch of Corbin’s sandeel, with smooth sandeel accounting for 90.15 % of the total catch rate. Clear spatial differences in the catch rates and species composition were observed, with considerably higher catch rates to the east of Fair Isle compared to the west and overall highest catch rates in the shallowest areas of each bank. Comparison of these results with historic survey data available from the Shetland area (1997-1999), indicates that while the overall sandeel catch rate observed from Fair Isle in 2025 was within the range of historic monthly average catch rates, there was a difference in species composition with historic catches being generally dominated by Raitt’s sandeel.

Dr Shaun Fraser, Senior Scientist and Fisheries Lead from UHI Shetland, who led the recent survey work at Fair Isle commented “The prevailing assumption in the scientific literature is that Ammodytes marinus (Raitt’s sandeel) is the dominant sandeel species across the North Sea. What the new data from Fair Isle indicates is that a related species, Gymnammodytes semisquamatus (smooth sandeel), was the most abundant, and to some extent may have replaced Raitt’s sandeel in the area. Although superficially similar, these two species have substantially different reproductive ecologies with smooth sandeel thought to spawn later in the year which has potentially profound implications for the wider ecosystem, for example by affecting prey availability during the seabird breeding season”.

Susannah Parnaby, Fair Isle resident and Fair Isle Marine Research Organisation (FIMRO) trustee said “The findings of this report highlight the importance of the whole ecosystem approach underpinning the research priorities for the Fair Isle DR MPA. Sustaining the charismatic and visible seabirds and cetaceans that inhabit our waters depends so often on understanding what is going on under the surface. We would like to thank all our DR MPA partner organisations and the funding bodies that make research like this possible, particularly since project findings here are likely to have much wider applications to other Scottish and North Sea seabird colonies.”

“This new dataset builds on four years of baseline inshore fisheries data for Fair Isle collected through the Fair Isle DR MPA project, and provides crucial additional detail on sandeel populations, which we know are an incredibly important food source for Fair Isle seabirds,” said Katie Cubbon, Research Officer for the Fair Isle DR MPA. “We aim to expand sandeel research in Fair Isle by combining targeted fisheries surveys with seabird diet studies. This integrated approach will provide a deeper understanding of how potential shifts in sandeel populations may affect breeding seabirds on Fair Isle.”

This project was supported by funding from the Viking Community Fund. Match funding for this project was also provided by players of the People's Postcode Lottery through the National Trust for Scotland's Love our Nature project.

You can view the report here: https://pure.uhi.ac.uk/en/publications/survey-report-for-the-2025-fair-isle-sandeel-survey/