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 degrees 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 nor 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 LD50 lower than 3.5 X 10(3).