Aquaculture for all

Dealing with ISA: Scottish Industry Holds its Breath

Salmonids Health Biosecurity +12 more

SCOTLAND, UK - The Scottish Government has reported that all fish from farms confirmed and suspected to have been affected by this week's outbreak of Infectious Salmon Anemia(ISA) have now been removed.

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Map of designated control zones in Shetland
Image: Scottish Government

The government says that the last site with fish that was under suspicion was inspected on Tuesday. There were no obvious signs of clinical disease or causes of particular concern regarding the health of the fish and samples of fish were taken from this site for diagnostic testing at the Fisheries Research Service (FRS) Laboratory in Aberdeen.

Meanwhile, Fish Health Inspectors are making their way around all fish farms that fall into the Control Zone and the Surveillance Zone. Where there is evidence of high levels of morbidity, or other signs of disease, samples from fish will be taken for testing. There are a total of 42 fish farming sites within the Control and Surveillance Zones of which 16 have fish in cages. The remaining 26 are either fallow or are presently not in operation. The inspection team intends to complete its efforts by 9 January, 2009.

It will take approximately six weeks to culture the samples and establish definitively the presence of the virus, but the first indications of the results should be known as of next week.

The source of the ISA outbreak is also under investigation. According to the Scottish Government: "the source of the occurrence will be the subject of a scientific study to determine the source of this new infection, the distribution of the disease in the environment and the risk of further spread."

"The source of the occurrence will be the subject of a scientific study to determine the source of this new infection"
Scottish Government

Following the last Scottish outbreak, government and industry worked together to establish a code of practice to minimize the effects of ISA. Importation of live salmonids is currently prohibited except from areas of equivalent health status and imports of live fish into Scotland have not been allowed from Norway, Chile or Canada, which have all suffered from major outbreaks of ISA.

ISA is transmitted between fish by direct contact with infected blood, urine, faeces and body fluids. Movements of live fish pose the greatest risk of spread of disease. Untreated effluent from processing plants has also been identified as being a particular risk.

The previous outbreak of ISA in Scotland in 1998-99 was estimated by industry to have cost £30 million. That was significantly more widespread and affected all fish farming areas of Scotland, and the majority of fish farming companies. Prompt action to remove farmed fish from infected areas, with the co-operation of the salmon farming industry, succeeded in eradicating the disease after that outbreak.

The Scottish Government has added that it will give very careful consideration to any claim for compensation for stock that has to be compulsorily destroyed.

Further Reading

- For more information on ISA, view The Global Spread of Infectios Salmon Anaemia by clicking here.