Photo: E. Peter Steenstra/USFWS

Infectious hematopoietic necrosis (IHN) virus has been detected in three privately-owned Atlantic salmon marine pen complexes in Rich Passage near Bainbridge Island.

American Gold Seafoods, which owns the Orchard Rocks, Fort Ward and Clam Bay complexes, is taking action to depopulate the infected net pens. The Washington Department of Fish and Wildlife is responsible for ensuring this happens as quickly as possible. The virus was confirmed May 8, and American Gold Seafoods expects to harvest or destroy at least 400,000 fish from the three sites by mid-June. Consuming affected fish is not harmful to humans.

IHN is not new to Puget Sound. It is found each year at some level in sockeye returning to spawn. However, this is the first reported detection of IHN virus in Atlantic salmon in marine net pens in Washington. Researchers have found that Atlantic salmon, an exotic species in these waters, are more susceptible to IHN than native Pacific salmon. The virus likely was picked up from infected fish in marine waters, possibly from out-migrating sockeye smolts from the Baker, Cedar and Ozette watersheds, where IHN was detected during the past year.

“We are concerned about the virus amplification that is occurring from the affected pens, and the length of time the amplifying event is occurring over,” said Bruce Stewart, fish health program manager for the Northwest Indian Fisheries Commission. “American Gold reported increased mortalities starting in April. We now are at end of May and infected fish are still in those pens shedding virus.”

Tribal fisheries managers are concerned that native salmon will be infected as they migrate through the area. NWIFC is working with the Suquamish Tribe to beach seine chinook, chum and pink salmon in Rich Passage and test them for the virus.

“We do not know what effect, if any, virus exposure will have on these fish,” Stewart said.

Another concern is the risk to captive broodstock from endangered runs being reared at the National Oceanic and Atmospheric Administration’s Manchester facility.

“Several tribes are rearing salmon at Manchester as part of recovery programs,” Stewart said. “Manchester’s saltwater intake is very close to the Clam Bay net pen site where the virus has been found.”

Although the salt water at Manchester is passed through a sand filter and then is disinfected with ultra-violet light, any breach in the system could result in the virus infecting one of those broodstock programs and jeopardize egg or fish transfers off site, Stewart added.

For more infomation, contact: Bruce Stewart, NWIFC fish health program manager, 360-528-4338 or stewart@nwifc.org.