Ireland’s National Crayfish Plague Programme (NCPP) represents a coordinated, science-led response to one of the most significant threats facing the country’s native freshwater biodiversity: crayfish plague.
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Originally established in 2018 as the National Crayfish Plague Surveillance Programme (NCPSP) under a Memorandum of Understanding between the Marine Institute and the National Parks and Wildlife Service (NPWS), the programme was developed following confirmed outbreaks of the disease caused by Aphanomyces astaci.
Based on a Norwegian model, the programme integrates advanced molecular diagnostics with conservation objectives for the White-clawed crayfish (Austropotamobius pallipes), Ireland’s only native crayfish species. From the outset, it has provided a national framework for understanding the presence, spread, and long-term risks posed by crayfish plague.
Programme Development and Progress
2018–2019:
The initial phase delivered Ireland’s first coordinated national environmental DNA (eDNA) surveillance across 28 catchments. This work demonstrated that eDNA-based qPCR is an effective surveillance tool, allowing detection of the pathogen even where no visible crayfish mortality occurs. It also established a baseline for disease prevalence across the country.
2020–2021:
The programme evolved to examine not just presence, but also disease distribution, persistence, and seasonal patterns. Time-series sampling clarified temporal dynamics, while multiplex assays strengthened biosecurity capacity by enabling simultaneous detection of crayfish plague, native crayfish, non-indigenous species, and other potential vectors.
From 2022 onward:
The NCPSP transitioned into the broader National Crayfish Plague Programme (NCPP). This phase has incorporated:
- Method refinements and passive sampling trials
- Improved genotyping of A. astaci
- Structured recovery and case study analyses
These developments have strengthened the programme’s role in informing national management and conservation decisions.
Key Milestones
A major breakthrough occurred in 2024 during the Awbeg River outbreak, when surveillance data enabled Ireland’s first emergency rescue and translocation of White-clawed crayfish from an actively spreading plague front.
In 2025, conservation detection dogs were trialled alongside eDNA monitoring to support faster and more effective field assessments.
The programme remains adaptive, continually evolving in response to new evidence and technological advancements rather than operating as a fixed framework.
Future Directions
Key scientific and management questions remain, including:
- How the disease spreads between catchments
- How long the pathogen persists in the environment
- What conditions enable population recovery
- Whether resistance may develop in crayfish populations
To address these challenges, the proposed 2026–2030 framework will expand into population genomics to inform refuge (ARK) site designation and guide translocation strategies for long-term conservation.
Update on Crayfish Plague in Ireland
The Fish Health Unit at the Marine Institute has confirmed the presence of crayfish plague in multiple Irish catchments. These detections are based on DNA data from both crayfish mortality samples and water filtration (eDNA) analysis conducted as part of the national programme.
What is Crayfish Plague?
Crayfish plague is a highly infectious and frequently lethal disease caused by the fungal-like organism Aphanomyces astaci. It can result in mortality rates of up to 100% in infected populations.
The disease poses a severe threat to the survival of the White-clawed crayfish, which is globally threatened and native only to Europe, with Ireland representing an important stronghold.
Genotyping analysis by WOAH reference laboratories in the UK and Finland has identified at least three distinct strains of A. astaci in Ireland. This indicates multiple introductions of the pathogen and highlights the urgent need to better understand its sources, transmission pathways, and current distribution.
The first confirmed outbreak in Ireland was recorded in 2015 in the Bruskey River (Erne catchment). Since then, the disease has spread to a growing number of catchments, including:
- 2017: Suir, Deel, Barrow & Lorrha
- 2018: Ulster Blackwater, Clare & Al
- 2019: Nore, Maigue, Slate & Shannon
- 2021: Clodiagh (Shannon 25A), Moy, Sligo
- 2023: Munster Blackwater
Further analysis is ongoing to determine potential links between outbreaks.
Biosecurity Measures: For All Waterway Users
- Check for mud, plant material, or animals on equipment
- Clean thoroughly using disinfectant or hot water
- Dry for at least 48 hours (preferably up to one week)
Further Information
The National Crayfish Plague Programme continues to monitor crayfish populations and water bodies across Ireland using advanced eDNA methods.
Programme reports are available:
- National Crayfish Plague Surveillance Programme Report (2018–2019)
- National Crayfish Plague Surveillance Programme Report (2020–2021)