A deadly fish virus has forced a Bainbridge Island, Washington (USA) salmon farm to destroy its entire stock and has put state wildlife experts on alert for additional outbreaks.

The Kitsap Sun reported last month that more than a million pounds worth of Atlantic salmon had been cleared from infected net pens in Rich Passage to the south of the island.

The Infectious Hematopoietic Necrosis virus, or IHN virus, can be carried by other fish, including herring, which sometimes pass through the farm’s net pens. The same virus recently appeared in two British Columbia fish farms, requiring the destruction and disposal of 560,000 fish. The virus had never been recorded in Washington waters until it was found at the Bainbridge Island farm last month.

The Bainbridge farm is owned by American Gold Seafoods, affiliated with Icicle Seafoods of Seattle. The company is also concerned about another batch of net pens about a half-mile away. The nets from two acres worth of pens will be removed and disinfected, and in four months the farm will be back in operation.

The dead and dying fish will be composted, although the living fish will still be processed and sold for food, in spite of most not having grown to the preferred market size.

South of the border, Chile knows a thing or two about salmon farm diseases. In 2010 the country’s salmon aquaculture industry saw production cut in half by outbreaks of the Infectious Salmon Anemia virus (I.S.A.) that spread through the fish farms in the southern part of the country. The Chilean farmed salmon industry suffered more than $2 billion in losses, saw its production of Atlantic salmon fall by half and the farms are still battling the disease.

But a novel new technology is revealing a silver lining to the cloud of massive farmed fish die-offs:

Biogas.

Equipment manufacturers Global Fluid S.A. and Landia have developed a line of pumps, seals and choppers to process the infected fish into fish silage, preventing further contamination, but also producing valuable, protein-rich fats and oils for use in biogas plants and paint manufacturing. The salmon are macerated in custom-engineered silage processing units, which comprise a stainless steel tank, chopper pump, control panel, recirculation pipe and valves.

When they enter the Silage Processing Unit, dead salmon weighing as much as 18 lbs. are successfully macerated into slurry by an aggressive chopper pump. Propeller mixers are used to agitate the silage during storage, which can be held in tanks for several months or even up to a few years when correctly produced and handled.

Biogas can be compressed, much like natural gas, and used to power motor vehicles, and as a renewable fuel, Biogas qualifies for renewable energy subsidies in some parts of the world. While not the ideal solution to the world’s energy problems, at least the diseased Chilean fish aren’t making it to the dinner table.