Shades of the Sea: Remote Sensing of River Plumes and Salmon Migration Cues

What if the sea could guide us home? That’s the question at the heart of Shades of the Sea, a new research internship led by Mhairi Hallford (University of Aberdeen) and supported by a cross-institutional team from UHI Inverness, the University of Strathclyde, and the Tweed Foundation, funded by QUADRAT DTP (UKRI).

Supervised by Dr. Samantha Beck (Institute for Biodiversity and Freshwater Conservation, UHI Inverness), Mhairi is investigating whether satellite imagery can reveal subtle shifts in coastal ocean colour - signals that may help Atlantic salmon find their way back to their home rivers to spawn. While we know salmon rely on freshwater olfactory cues and possibly visual cues during their migration, it remains unclear how these extend into the ocean, or how environmental changes might disrupt them.

The project asks two key questions:

• Do different rivers have unique colour “fingerprints” that extend into the ocean?
• Do these colour patterns vary in ways that align with the timing of salmon returns?

By combining satellite data with salmon ecology, the project revives ancient mariner wisdom - once used by Vikings to locate rich fishing grounds - and applies it through a modern lens. As climate change reshapes coastal environments, understanding these visual migratory cues could be vital to conserving this iconic and culturally important species.

Project Team:

• Intern: Mhairi Hallford (University of Aberdeen)
• Supervisor: Dr. Samantha Beck (IBFC, UHI Inverness)
• Project Partners: Prof. David McKee & Dr. Neil Banas (University of Strathclyde), Dr. James Hunt (Tweed Foundation), Dr. Sarah Wagner & Dr. Melanie Manwaring-McKay (CLS, UHI Inverness)