Vibrio spp. isolated from salmonids with shallow skin lesions and reared at low temperature

In Iceland the rearing temperature of salmonid fish, mostly Atlantic salmon, is generally below 10°C. Infections most often characterized by shallow skin lesions that may cause considerable mortality have been endemic in the country since rearing in salt water started. A variety of Vibrio spp. has been isolated from the diseased fish. In the present study, a total of 58 strains isolated from salmonid fish and 21 reference strains were subjected to a numerical taxonomy study. The results show that two phena are most common in the diseased fish; one of them includes V. marinus , whereas the other does not include a reference strain but has similarities to V. logei . Challenge tests showed that a representative strain of the phenon that included V. marinus is pathogenic for Atlantic salmon with an LD 50 lower than 3.5 × 10 3 .