In recent years use of cleaner fish as biological agents of salmon-lice control has increased dramatically, largely due to the increasing prevalence of resistance in salmon-lice to chemical treatments. Although various fish species may be used for this purpose, the lumpsucker, Cyclopterus lumpus is becoming increasingly popular. Although many of the various cleaner fish species may be caught from the wild, all lumpsucker used as cleaner fish in Norway are farmed.
While lumpsucker appear to be generally robust, during 2013 the Norwegian Veterinary Institute diagnosed systemic infection involving a member of the Pasteurellaceae in this fish species in 16 different aquaculture facilities. Both juvenile production sites and stocks ‘at work’ in marine salmon sites were affected. In some cases infections were associated with mortality levels approaching 100%.
Phenotypically the lumpsucker isolates are highly similar to an unspeciated Pasteurella sp. previously associated with systemic infection in farmed Atlantic salmon in Norway and less similar to Pasteurella skyensis isolated from diseased Atlantic salmon in Scotland. Genetically (16S rRNA) the Norwegian isolates from both lumpsucker and Atlantic salmon comprise a homogenous group most closely related to P. skyensis and Phocoenobacter uteri, a bacterium of unknown pathogenic significance isolated from the uterus of harbor porpoise Phocoena phocoena. At the present time it is not known whether the Norwegian isolates represent a novel species or subspecies within the Pasteurellaceae. The results of a preliminary phenotypical and genetic characterization will be presented.