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DAO
Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03508

    Longitudinal survey of Flavobacterium species in Icelandic salmonid fish farms

    Thorbjorg Einarsdottir*, Gudbjorg Guttormsdottir, Daniel Connaghan, Sigridur Hjartardottir

    *Corresponding author:

    ABSTRACT: Flavobacterium species cause significant disease in salmonid farming worldwide, typically seen as mortality in sac fry, and later as necrosis and ulceration in fingerlings and fry. In this study, we sampled Atlantic salmon Salmo salar and Arctic char Salvelinus alpinus from five Icelandic fish farms in 2014 and 2017, where flavobacteria were suspected to cause disease. The objective of the study was to identify and characterise the bacteria, by sequencing the 16S rRNA gene and multilocus sequence type housekeeping genes. We found five distinct groups of flavobacteria, three of which were homogeneous and appeared to persist in the fish farms between 2014 and 2017, and two groups of flavobacteria that were heterogeneous and transient. Flavobacterium psychrophilum could be isolated from diseased Arctic char from all five fish farms in both 2014 and 2017. However, while the other four Flavobacterium sp. groups were isolated from Atlantic salmon, water and roe, F. psychrophilum could not be isolated from these samples. This indicates that flavobacteria other than F. psychrophilum may be the primary cause of fin and tail rot in Icelandic Atlantic salmon fry.