National Survey of Sea Lice (Lepeophtheirus Salmonis Krøyer and Caligus Elongatus Nordmann) on Fish Farms in Ireland – 2025

This report provides an overview of the sea lice data collected from Ireland’s National Sea Lice Monitoring Programme in 2025. A total of 192 sea lice inspections were carried out all 22 active Atlantic salmon (Salmo salar) production sites. Ninety-eight percent of sea lice inspections were below the Treatment Trigger Levels (TTL). There were 126 inspections on salmon smolt sites, 99% of which were below the TTL and 66 inspections of one-sea-winter salmon sites; 95% were below the TTL. Mechanical and biological methods of control of sea lice continue to have a positive effect on sea lice management in Ireland. In addition to monitoring, the Marine Institute also launched a Power BI dashboard in 2025 which displays monthly salmon lice counts for each salmon farm with historical data for each stock of fish since they were put to sea. The dashboard, which is publicly available, aims to provide more transparency for the data collected by the Marine Institute. Elevated salmon lice levels continue to be the exception rather than the rule and the proactive management measures used are proving to be effective in continuing the overall decline in sea lice abundance on all marine Atlantic salmon farms in Ireland over the past 30 years.

URI

https://oar.marine.ie/handle/10793/2182

Description

Dashboard: https://www.marine.ie/site-area/data-services/sea-lice-inspection-data-finfish-farms-ireland

Citation

O'Donohoe, P., D'Arcy, J., Kelly, S., McDermott, T., and Ruane, N. (2026). National Survey of Sea Lice (Lepeophtheirus Salmonis Krøyer and Caligus Elongatus Nordmann) on Fish Farms in Ireland – 2025. Irish Fisheries Bulletin No. 57. Marine Institute, Ireland