In the autumn of 1984, a new disease was observed in Atlantic salmon being farmed along the southwest coast of Norway. The disease, which was named Infectious salmon anemia, spread slowly. ISAV, a RNA virus, is the only species in the genus “Isavirus” which is in the family Orthomyxoviridae, it appears to be most like influenza viruses. Its mode of transfer and the natural reservoirs of infectious salmon anemia virus are not fully understood. By June 1988 it had become sufficiently widespread and serious to require the Norwegian Ministry of Agriculture, Fisheries and Food to declare it a notifiable disease.
ISA is a viral disease of Atlantic Salmon (Salmo salar) that affects fish farms in Canada, Norway, Scotland and Chile, causing severe losses to infected farms. The disease is listed as a non-exotic disease of the EU and is therefore watched closely by the European Community Reference Laboratory for Fish Diseases.
In Chile, ISA was first isolated from a salmon farm in the 1990s and described for the first time in 2001 although the initial presence never resulted in widespread problems. However, since June 2007, the national industry has been dealing with a serious ISA outbreak which has not yet been completely brought under control and has been responsible for an important decline in the industry, closure of many farms and high unemployment. In 2008 there has been an outbreak of ISA in Shetland.
There is no treatment once fish are infected.
Infectious salmon anemia is currently regarded as a serious threat not only to farmed Atlantic salmon, but also to dwindling stocks of wild Atlantic salmon. Recent research involving a multi-year study of wild Atlantic salmon from North America shows that infected salmon that survive infection generate antibodies against the virus. More about ISA: Wikipedia
We don’t know so far if after bird flu and swine flu there might be a salmon flu threatening humans in the near future. There are indications that this influenza virus can mutate and affect man.
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The Norwegian company TINE SA (known mainly for dairy products) has apparently recently decided to sell its majority shares in Salmon Brands AS (SALMA brand) according to a publication on 19.02.2012 on http://www.nmf.no/. This is probably due to the fact that “fish farm installations had difficulties during the past years” and the article mentions “steadily falling prices” of the fish, so that fish farming is no longer an interesting investment proposition.
There has also been issues in Finnvik (Tromsø) and generally in the northernmost county of Finnmark with sick fish – at least 2 million of Salmar Nords’ fish had to be culled because they were infected with Pancreas Disease (PD). According to Merck (http://aqua.merck-animal-health.com/diseases), PD “is an important economic disease of European farmed Atlantic salmon. It can cause significant losses due to morbidity, mortality and reduced production. Chronic PD has also been known as ‘sudden death syndrome’ (SDS). […] The causative agent was only isolated in 1995 and was shown to be an alphavirus, now known as Salmon Pancreas Disease Virus (SPDV).” Recent studies have indicated that it is very similar to ‘Sleeping disease virus’ of rainbow trout. “Pancreas Disease has been described in Scotland, Norway, Ireland, France and the west coast of the USA in farmed Atlantic salmon. Due to the difficulty of isolating SPDV from natural outbreaks of PD and the widespread distribution of Infectious Pancreatic Necrosis virus (IPNV), which can mask the SPDV and the disease in farmed salmon, PD is significantly under diagnosed in the field. […] Transmission is primarily due to direct fish-to-fish contact, but the involvement of other marine reservoirs such as molluscs, crustaceans and wild fish, or vectors such as sea lice, cannot be ruled out.” If you find this is scary, there’s more on that website selling pharmaceuticals to the fish industry!
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