Piscine myocarditis virus (PMCV), a double‐stranded RNA virus, is the causative agent of cardiomyopathy syndrome (CMS) in Atlantic salmon Salmo salar , which was first reported in Ireland in 2012. PMCV continues to be a disease threat to Atlantic salmon aquaculture in Ireland, and as such, it is of growing importance to understand how the virus spreads. Genetic sequences allow for transmission pathways to be examined, with who...

Marine aquaculture has the potential to increase its contribution to the global food system and provide valuable ecosystem services, but appropriate planning, licensing and regulation systems must be in place to enable sustainable development. At present, approaches vary considerably throughout the world, and several national and regional investigations have highlighted the need for reforms if marine aquaculture is to fulfil i...

Epitheliocystis, an intracellular bacterial infection in the gills and skin epithelium, has been frequently reported in Atlantic salmon ( Salmo salar ) during freshwater production in a number of countries. This study describes the prevalence and intensity of a natural epitheliocystis infection present in the gills of two strains of Atlantic salmon reared in either a flow‐through (FT) or a recirculation aquaculture system (RAS...

European North Atlantic ranavirus (ENARV, Iridoviridae ), is a ranavirus species recently isolated from lumpfish ( Cyclopterus lumpus , L.), which are used as cleaner fish in Atlantic salmon ( Salmo salar ) farming in Northern Europe. This study aimed to investigate (1) the virulence of ENARV isolates from Ireland, Iceland and the Faroe Islands to lumpfish; (2) horizontal transmission between lumpfish; and (3) virulence to Atl...

Piscine orthoreovirus genotype 1 (PRV‐1) is widespread in farmed Atlantic salmon ( Salmo salar L.) populations in northern Europe, Canada and Chile. PRV‐1 occurs in wild fish in Norway and Canada; however, little information of its geographical distribution in wild populations is currently available, and the effect of PRV‐1 infection in wild populations is currently unknown. In this study, we present the findings of a survey c...

Piscine myocarditis virus (PMCV) is a double‐stranded RNA virus which has been linked to cardiomyopathy syndrome (CMS) in Atlantic salmon ( Salmo salar L.). The first recorded outbreak of CMS in Ireland occurred in 2012. Heart tissue samples were collected in the current study from farmed Atlantic salmon from various marine sites around Ireland, and the open reading frames (ORFs) 1 and 3 were amplified and sequenced in order t...

The use of cleaner fish as a biological control for sea lice in Atlantic salmon aquaculture has increased in recent years. Wild‐caught wrasse are commonly used as cleaner fish in Europe. In Ireland, samples of wrasse from each fishing area are screened for potential pathogens prior to their deployment into sea cages. Salmonid alphavirus was isolated from a pooled sample of ballan wrasse, showing no signs of disease, caught fro...