November 26, 2007

Sites Close and Surveillance Increases in Chile's ISA-ravaged Waters

Five new outbreaks of infectious salmon anaemia virus have been reported in Chile. More than 5.5 million have been affected and a major culling operation has been underway on affected sites in a bid to contain the disease.


Dr. Claudio Ternicier Gonzáles, of Chile's Ministry of Agricuture Fisheries Division, confirmed that two outbreaks of the virus were on Isla Lemuy and Los Lagos, with further outbreaks on Isla Tranqui , LinLin, and Islas Butachauques.

The disease was found in Salmón del Atlántico (Salmo salar), which were being farmed in semi-open salt water costal areas. The initial outbreak, of the disease was reported in June, measures were put in place to reduce the potential spread of infection, but the disease is now getting a stronghold and causing massive financial hardship to Chile's US$2.4 billion farmed salmon sector.

The latest ISA outbreaks were reported to the World Animal Health Organisation (OIE) this week. The source of the infection is unknown, although the OIE Reference Laboratories has the ISA strain to be the European genotype.

Infectious salmon anaemia was detected in Chile in 1999, but in this incident only Coho Salmon (Oncorhynchus kisutch) were infected. The current ISA outbreak is affecting Atlantic salmon (Salmo salar).

The Chilean authorities have now established a 5-km-radius navigable quarantine zone around the affected culture premises. All channels bordering Lemuy Island, Butachauques Island, Lin Lin Island and the area of Queilén Channel have been placed under surveillance.

The National Fisheries Service is also investigating five other suspected cases in the Chiloe Islands.

Marine Harvest, the world’s largest farmed salmon company, says it plans to close several of its salmon farms in this area and move operations toward the less-crowded waters of Region XI (Aysén).

Commercial interests now believe that the level of infection in Chilean stocks is more serious than either the government or the country's major salmon producers have been willing to admit. Many are reviewing their position and introducing measures to curb losses.

ISA poses a serious threat; it is highly contagious and spreads very easily in confined production systems. Marine Harvest says it has had six or seven cases and feels it has no option but to close certain sites and move operations to unaffected waters.

Marine Harvest says it is not the only salmon producer affected by the disease. The ISA epidemic is also crippling other aquaculture companies in the region.