Study Links ISA in Chile to Salmon Eggs from Norway

A study by Cermaq concludes that the best explanation for the infectious salmon anaemia (ISA) virus in Chile is transmission from Norwegian salmon eggs. Previous studies have linked the ISA virus strain found in Chile to the ISA virus strain previously found in Norway.

The latest study has been mired in controversy since its publication in 2008 due to the potentially serious implications that it could have for the salmon industry.

Aqua Gen, a Norwegian company that breeds fish eggs and the principal supplier of salmon eggs to Chile since 2006, filed a formal complaint against the study with Norway's National Commission for the Investigation of Scientific Misconduct in 2009. However, the Commission ruled in April that the report's authors were not guilty of scientific misconduct.

The implications of the study go beyond who might be responsible for initially introducing the virus – which ultimately led to US$2 billion in damages, the loss of 50 per cent of production and the loss of 26,000 jobs in Chile.

The study suggests that the virus can be transmitted through eggs, although this is still disputed by experts. A conclusion could affect the way that salmon eggs are regulated internationally.

Indeed, even Chile's National Fishing Service (Sernapesca) has said that it does not fully support the findings of the Cermaq study but rather endorses the World Organization for Animal Health's conclusion that there is insufficient evidence to support the theory of transmission through eggs.

A new egg importation law took effect last year. Even though the industry is recovering, ISA continues to haunt Chile. The stock price of salmon companies has fallen almost 15 per cent this month in response to suspicions of a non-harmful strain of ISA at 23 aquaculture centres.

Salmon farming profits could also be affected in the long term. Renewed salmon production has led to decreased international prices for the commodity. With an increase in production from Chile predicted, officials expect the low prices are here to stay.

Recent sanitary regulations in Chile, implemented to avoid future ISA outbreaks, will also be costly to implement and are also likely to impact profits, officials say.

Also reported this week, a study at Oregon State University in the US suggests that parasites in fish, including threatened species of Oregon coho salmon, may have more profound impacts on fish health than had been assumed, and could be one of the key mechanisms by which habitat and land use changes cause salmon mortality.

Europe's key aquaculture event, AquaNor 2011, starts in Trondheim, Norway, today. Charlotte Johnson, editor of TheFishSite, will be reporting on the show during the week.