Aerial view of Aasleagh Falls on the River Erriff.

National Salmonid Index Catchment | Erriff

Over the past few decades, the overall number of Atlantic salmon returning to Ireland’s rivers to spawn has declined. This is a cause for concern because salmon are a species that connect water quality in the smallest headwater streams with distant marine ecosystems that are changing at an oceanic scale.

Learning to inform

Research into the biology, life-histories and populations of the salmonid family of fishes, which includes salmon and trout, can help us to understand the effects of environmental and man-made pressures on them and enable us to better inform policy on the conservation and management of these socio-economically important species. 

The Erriff, a prime example

The River Erriff in Co. Mayo is one of Ireland’s premier salmon fishing rivers and has been designated as the National Salmonid Index Catchment (NSIC). This means that it is being used as a prime example of a salmonid river system that is of high quality. The NSIC offers a great opportunity to study these fish under ecological conditions that are close to the natural state for the type of river systems, which provide the best habitat for salmonids in Ireland.

A dedicated research facility

A dedicated research station with fish counting and trapping facilities is located at Aasleagh Falls by the mouth of the River Erriff on Killary Harbour. This research facility is managed by Inland Fisheries Ireland and supports a wide range of scientific research and monitoring activities on salmon, sea trout and brown trout.

Our research activities

Activities include fish counting to monitor stock changes from year to year, fish tracking to assess survival during migration in the freshwater and marine zones, assessment of impacts of sea lice associated with marine salmon farming on wild fish, disease monitoring, climate change research, and studies of salmonid habitat and life cycle to better understand the factors that support healthy populations.

This work involves cooperation between Inland Fisheries Ireland and a range of national and international research partners.

Anglers at Aasleagh Falls on the River Erriff.