Systemic spironucleosis in sea-farmed Atlantic salmon Salmo salar, caused by Spironucleus barkhanus transmitted from feral Arctic char Salvelinus alpinus?

Abstract

A hexamitid flagellate was found in the gall bladder and intestine of Arctic char Salvelinus alpinus in northern Norway, Scanning and transmission electron microscopy showed this flagellate to be identical to Spironucleus barkhanus from grayling Thymallus thymallus and farmed Atlantic salmon Salmo salar. It is hypothesised that systemic spironucleosis in sea-caged Atlantic salmon was due to transmission of flagellates from feral char to the salmon.