The return of Atlantic salmon to the River Roe is one of the most anticipated signs of the season. Yet while much is known about salmon in our rivers, far less is understood about what happens after young fish leave freshwater and begin their journey towards the North Atlantic.

An international research project published in 2024 has helped answer some of those questions. The study tracked Atlantic salmon smolts from twelve rivers across Ireland and the UK, including the River Roe, providing new insights into the early marine phase of their remarkable migration.

Following Salmon Beyond the River

In spring 2021, researchers fitted young salmon with miniature acoustic transmitters before they left their natal rivers. A network of underwater listening stations positioned throughout coastal waters around the Irish Sea and North Channel recorded the movements of tagged fish as they migrated towards the North Atlantic.

The River Roe was among the rivers selected for the study, alongside other catchments in Northern Ireland, Ireland, Scotland and England.

What Did the Study Find?

The results show that River Roe salmon move rapidly through the coastal environment after leaving Lough Foyle. Among the rivers included in the study, River Roe salmon were recorded as having some of the fastest migration speeds during this early stage of their marine journey.

The research also found that salmon from the Roe and neighbouring Faughan generally followed a similar migration pattern, tending to remain closer to the Irish coastline as they moved north-westwards and towards the North Atlantic.

These findings help build a clearer picture of how local salmon populations use coastal waters and the routes they take during one of the most challenging stages of their life cycle.

Why Does This Matter?

The period immediately after salmon leave freshwater is widely recognised as one of the most vulnerable phases of their lives. During this time, young fish must successfully adapt to seawater, avoid predators, locate feeding opportunities and navigate towards distant oceanic feeding grounds.

Understanding where salmon travel and how they behave at sea is essential for effective conservation and fisheries management. Studies such as this help scientists and managers identify important migration corridors and improve understanding of the factors influencing salmon survival.

An Atlantic Migration

The study is a powerful reminder that the salmon of the River Roe are part of a much larger Atlantic story.

Every salmon that returns to the River Roe begins life in the river before embarking on an extraordinary migration through Lough Foyle and the coastal waters of the North Channel before continuing into the North Atlantic and eventually finding its way back to its home waters.

Research continues to improve our understanding of these migrations, but studies such as this provide valuable new evidence of the routes used by River Roe salmon and the challenges they face beyond our shores.

Reference: Lilly, J., Honkanen, H.H., Rodger, J.R. et al. (2024). ‘Migration patterns and navigation cues of Atlantic salmon post-smolts migrating from 12 rivers through the coastal zones around the Irish Sea’. Journal of Fish Biology, 104(1), 265-283. Read the full paper online.