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Mouth rot - Tenacibaculum maritimum - tracking pathogenesis and typing



This project will improve our understanding of the pathology and epizootiology of mouth rot in Atlantic salmon in British Columbia. Mouth rot (also referred to as yellow mouth in the United States) is a disease of farmed Atlantic salmon (Salmo salar). The causative agent is the filamentous bacterium Tenacibaculum maritimum (formally Flexibacter maritumus). The natural reservoirs of the causative agent are unknown. At sites of disease outbreaks T. maritimum can be isolated from both sediments and water.

Clinically the disease is presented with fish exhibiting yellow plaques around the palate and teeth including the vomer. The extent of the lesions may range from single foci to multiple ulcerations on both the upper and lower jaws. The development of gross lesions and mortality due to this disease typically occur within the first 2 to 3 weeks following smolt entry into the seawater. However, once established this disease may re-occur in populations for a period of several months. Therapeutant treatments using sulpha antibiotics have been found to be useful in controlling this disease; however, multiple treatments are often required before the disease disappears.

Costs associated with this disease include direct mortality which can reach up to 30%, as well as treatment costs and the cost of lost production which results from infected fish being unable to feed properly. In BC fish health monitoring and audit programs, mouth rot (reported as myxobacterial infections) is the most commonly reported disease.

Mouth rot is a chronic and serious disease problem in Atlantic salmon aquaculture for which there is no vaccine and limited treatment options. The information that will be obtained during this study will aid the industry in developing of improved management strategies and techniques for mouth rot.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)


2009 - 2010


Pacific: Vancouver Island West Coast

Principal Investigator(s)

Stewart Johnson

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