August 3, 2016

Cermaq: Lumpsuckers effective against salmon lice, but with potential impact on fish

The employment of lumpsuckers in Norwegian aquaculture is a preferred, and perhaps, more friendly alternative to fight salmon lice compared to chemical treatments. But a recent Cermaq study found that its increased use may potentially introduce pathogens threatening salmon populations.

The salmon industry in Norway has find effective use of lumpsuckers - small scorpaeniform marine fish of the Cyclopteridae family – in combatting salmon lice and is thus deploying them in rising numbers, according to Cermaq which also employs the aqua species.

However, lumpsuckers could potentially be a double-edged sword and more research is needed to understand biological issues arising from the culturing of the fish. In its recent study, Cermaq discovered that the use of cleaner fish to control salmon lice has boomed in the last 10 years of salmon production in Norway. It is seen as a preferred alternative to chemical treatments. The latter option includes 'intentional inputs', specifically pesticides, drugs, antifoulants, anaesthetics and disinfectant, as stated in a research paper by the St. Andrews Biological Station, Rutgers University, New York Medical College and Universidad de Santiago de Chile.

The advantages of lumpsuckers is undeniable; however, the Cermaq study also uncovered the emergence of parasites and bacteria connected to the production and use of these fish. The company's clinical scientists, Sverre Bang Småge, Kathleen Frisch and Øyvind Brevik, released the first finding of Tenacibaculum maritimum, a major fish pathogen worldwide, in cultured juvenile lumpsuckers in Norway.

Affected fish were found to be lethargic and bearing skin lesions marked by increased mucus production and the presence of whitish necrotic tissue, especially in the head region. Skin scrapings from these lumpsuckers revealed a significant presence of bacteria closely related to T. maritimum, which was verified through sequencing and comparison to published T. maritimum isolates. Further analysis showed that the bacteria was closely associated with the pathology and therefore could be a contributor to the disease and / or mortality.

A key question will be whether lumpsuckers may be a vector for pathogens that may cause disease in salmon, Cermaq concluded.
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