2017 is starting on the wrong foot for Norwegian salmon farmer Grieg Seafood, which has just confirmed that 3000 metric tons of their farmed salmon is suffering from Infectious Salmon Anemia (ISA). By Norwegian law, these fish will have to be destroyed by the end of January. The site will then be laid fallow until new salmon smolts are introduced this spring. This sound like a huge number, but the site of the outbreak alone is home to over 1 million salmon and is a fraction of Grieg’s annual production of approximately 90,000 metric tons.
This may affect supply and cost for some consumers for 2017 and perhaps early 2018. However the company has stated that this will be offset with greater supply once the infected site is back operating.
What is Infectious Salmon Anemia?
ISA is a virus that is related to the flu and infects the red blood cells of Atlantic salmon. In the tight confines of salmon farms it can spread slowly or hit quick. Sometimes the fish struggle and look obviously unhealthy but other times the salmon look fine but then suffer a die-off. Infected fish farms can have a salmon mortality rate of between 80-100%.
The virus was first noticed in the 1980’s in fish farms in Norway, but could have been in the local ecosystem many decades before that. Since then ISA, along with the closely related hemorrhagic kidney syndrome has been seen in ocean-raised salmon farms from Scotland to Chile. The pathology of Infectious Salmon Anemia is still not fully understood, but sea-run species of trout have been found to be carriers but do not get sick. Another culprit could be the infamous sea louse, which plagues salmon farms and has shown to carry the virus.
ISA is a killer without a cure and the fish from an infected area are eradicated in the hope of eliminating the virus. Not only is this a major issue with fish farming, but it also threatens the few remaining wild stocks of Atlantic salmon. With aquaculture growing year by year ISA is a worldwide issue that needs to be addressed somehow. Currently attempts are being made to create vaccines for the various strains of Infectious Salmon Anemia.