The National Salmonid Index Catchment

Aasleagh Falls at the mouth of the River Erriff system
Aasleagh Falls at the mouth of the River Erriff system

The River Erriff system has been designated as the National Salmonid Index Catchment. A dedicated research station with fish counting and trapping facilities is located at Aasleagh Falls by the mouth of this prestigious Atlantic salmon and sea trout fishery which flows into Killary Harbour fjord on the Atlantic coast in the west of Ireland. The research facility is managed by Inland Fisheries Ireland (IFI) and supports a wide range of scientific research and monitoring activities on the resident salmonid populations and their migratory component as undertaken by the state agency and its national and international partners.

Erriff sea trout
Erriff sea trout

This work aims to contribute to the better understanding of the biology, life histories and population dynamics of Atlantic salmon and sea trout and the effects of environmental and anthropogenic factors on their continued sustainability. The output is applied to better inform the conservation and management of these socio-economically important species within Ireland and further afield. 

Fish pass and fish trap at Aasleagh Falls Research Station
Fish pass and fish trap at Aasleagh Falls Research Station

The wide range of ongoing Research and monitoring activities in the National Salmonid Index Catchment continue to build upon many decades of scientific work undertaken on salmonid populations in the Erriff system.  These activities contribute to the valuable Data resources already available to further our understanding and the sustainable management of these iconic fish species.

Please refer to the tabs below for further information on the catchment, research and monitoring infrastructure and activities, news and updates and additional information.


Catchment Information

The River Erriff system, designated as The National Salmonid Index Catchment, is one of the premier recreational salmonid fisheries in Ireland holding good stocks of Atlantic salmon, sea trout and brown trout. The system is located in County Mayo in the west of Ireland, near the village of Leenane (53° 37' 0.00" N: 9° 40' 17.10" W). 

Find out more...  Catchment information


Research and Monitoring Infrastructure

The research infrastructure at the National Salmonid Index Catchment, managed by    Inland Fisheries Ireland (IFI), include a research station with fisheries    laboratory, fish trapping facilities, an experimental hatchery, and an    extensive telemetry array.

Find out more...Research and monitoring infrastructure


Research and Monitoring Activities

A wide range of research and monitoring activities are undertaken by IFI in the National Salmonid Index Catchment, often in collaboration with national and international research partners. These are focused on the life histories, population dynamics, migration, and marine survival of salmon and sea trout, and the concomitant influence of environmental and anthropogenic factors. 

Find out more... Research and monitoring activities


News and Updates

Keep up to date with all the developments at the NCIS - News and updates


Data resources

Data resources


Source to Sea

Follow the Erriff River system from source to sea. An aerial fly through of the National Salmonid Index Catchment and its infrastructure. 

Watch it now... Source to sea


Related publications

A compilation of fisheries literature related to the River Erriff system including published scientific papers and reports 

Find out more... Related publications



Maps and more... Catchment location


Contact us

For information on how to contact the NCIS or Erriff Fishery - NSIC Contact details