New Microorganisms Linked To Gill Disease In Salmon

Terje M. Steinum's doctoral research has identified microorganisms that may lead to gill disease, thereby making a significant contribution to our understanding of such diseases in farmed salmon.

Gill disease poses a considerable problem to salmon farming. Disease-induced changes usually consist of massive lesions, which greatly reduce the surface area of the gills, thereby causing breathing problems which can lead to the death of the fish. These changes can have several different causes and cannot therefore be linked to one particular agent.

The main aim of the research was to identify microorganisms that are involved in gill disease by means of modern, molecular methods, combined with traditional, histopathological studies.

The results of Mr Steinum's work indicate that two bacteria, Ca. Pisciclamydia salmonis and another species, not yet named, plus a recently discovered unicellular parasite, Desmozoon lepeophtherii, play a role in the development of the gill disease called proliferative gill inflammation. In addition, the thesis shows that an amoeba called Neoparamoeba perurans, only recently discovered, is linked to the amoeba gill disease that was diagnosed for the first time in Norway four years ago.

Furthermore, Mr Steinum's thesis has increased our basic knowledge through its description of other bacteria that normally occur in the gills of diseased and apparently healthy fish respectively.

This doctoral research led to the publishing of four scientific articles and was carried out at The National Veterinary Institute (VI) in collaboration with The Norwegian School of Veterinary Science (NVH) in Oslo.

Terje M. Steinum, Cand.scient, presented his doctoral thesis on 20th October 2010 at The Norwegian School of Veterinary Science. The thesis is entitled: ”Microbial studies related to proliferative gill diseases in Atlantic salmon”.