First detection of Ichthyophonus sp. in invasive wild pink salmon (Oncorhynchus gorbuscha) from the North Atlantic Ocean

• Published in: Journal of fish diseases Vol. 47; no. 9; pp. e13990 - n/a
• Main Authors: Erkinharju, Toni, Hansen, Haakon, Garseth, Åse Helen
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-09-2024
• Subjects: Animals; Atlantic Ocean; Carnivorous animals; Clupea harengus; Cytochromes; Electron Transport Complex IV - analysis; Electron Transport Complex IV - genetics; Female; Fish Diseases - diagnosis; Fish Diseases - parasitology; Freshwater fishes; Gills; Ichthyophonus; Ichthyophonus sp; Introduced Species; invasive species; Marine fishes; Mesomycetozoea - genetics; Mesomycetozoea - isolation & purification; Mesomycetozoea Infections - epidemiology; Mesomycetozoea Infections - parasitology; Norway; Oncorhynchus gorbuscha; parasite; Parasites; Phylogeny; pink salmon; Rivers; RNA, Ribosomal, 18S - genetics; rRNA 18S; Salmon; Salmon - parasitology; wild; Norway; Atlantic Ocean; United States > US; Ichthyophonus sp; pink salmon; parasite; Oncorhynchus gorbuscha; wild; invasive species
• ISSN: 0140-7775; 1365-2761; 1365-2761
• DOI: 10.1111/jfd.13990

Pacific pink salmon (Oncorhynchus gorbuscha) were deliberately introduced to rivers surrounding the White Sea and has spread to Norway and several other countries surrounding the North Atlantic Ocean. In August 2021, a female pink salmon displaying pale gills and abnormal behaviour was captured in River Lakselva in Northern Norway and later submitted to the Norwegian Veterinary Institute (NVI) for post‐mortem examination. Histological examination of organ samples revealed structures indicative of systemic ichthyophoniasis, caused by Ichthyophonus sp. The parasites appeared to be especially abundant in the heart and skeletal musculature, and local tissue responses were assessed to be absent or very mild. Sequences of the ribosomal 18S rRNA and the mitochondrial cytochrome oxidase 1 (CO1) genes confirmed the diagnosis and identified the pathogen as Ichthyophonus sp. The CO1 sequence further established that the isolate from pink salmon was most similar to sequences of Ichthyophonus sp. from Atlantic salmon, Salmo salar, from the Atlantic Ocean on the east coast of the US and from Atlantic herring, Clupea harengus, from Iceland. We here report the first detection of Ichthyophonus sp. in pink salmon in the North Atlantic Ocean.