It’s called Pacific Oyster Mortality Syndrome. It poses no health risk to humans. However, it’s destroying oyster businesses in Western Europe, China and the South Pacific, and growers are now bracing for it on the U.S. West Coast.
Although researchers found the virus in California’s Tomales Bay and an adjacent bay in the early 2000s, more deadly “microvariants” of the virus have not been found so far in North America, according to Colleen Burge, assistant professor, at the Institute of Marine and Environmental Technology at the University of Maryland.
But Willapa oysters growers and West Coast shellfish agencies are giving the problem careful scrutiny.
Brian Kingzett is vice president and senior biologist of Goose Point Shellfish Farm and Oystery located in Bay Center. Owned and operated by the Nisbet family, Nisbet Oyster Co., Inc. employs more than 80 full-time men and women on their 1,900-acre farm. Kingzett oversees their state-of-the-art processing plant, which is considered a model facility by both the federal Food and Drug Administration and the Washington State Department of Health.
Kingzett has been in the oyster industry for more than 30 years. He is concerned this herpes-like virus could make its way into secluded Willapa Bay.
“Because of the impact it has had on other growing areas, we are treating its eventual show-up in the Pacific Northwest as an inevitability,” he said.
The Washington Department of Fish and Wildlife Shellfish Division has been closely examining the situation as well.
Brady Blake, WDFW’s shellfish disease program lead biologist, located in Port Townsend, explained the seriousness of the situation.
“This is an extremely high priority for our program. This disease can cause up to 100 percent mortality of the oyster. We are working with other state shellfish partners in Hawaii, Alaska, California and Oregon to form a strong prevention and response network. We are all very concerned about this,” he said.
What is Pacific Oyster Mortality Syndrome?
POMS is caused by the Ostreid Herpes virus type 1 (OsHV-1) virus. According to Kingzett, the disease originates in pathogens found in natural seawater and is specific only to Pacific oysters, which face a nearly complete die-off within days of infection.
The first case of POBS was described in 2008. A microvariant of OsHV-1 was found in France that year, and it killed 80 to 100 percent of oysters in infected beds. Since the 2008 outbreak, OsHv-1 has been discovered in Pacific oysters in the United Kingdom, Ireland, the Netherlands, Spain, Italy, Asia, Australia and just recently in New Zealand. In 2010, it killed 8 million oysters in England.
Some studies in Europe discovered that POMS was detectable in oysters after mortalities stopped. This indicates that surviving oysters can be carriers of the virus. Very little is known about the lifecycle of the disease.
Kingzett said the spread of POMS is theorized to be related to certain shipping routes, where the disease may be present in specific harbor locations.
POMS virus seems to thrive in warmer water temperatures, he said. This factor might be a saving grace for oyster growers in the Pacific Northwest, where water rarely exceeds 65 degrees. But Kingzett is still cautious.
“It might be that our water is cold enough that it won’t express here. But we are not sure,” he said.
“Once OsHV-1 is established within a bay, mass oyster deaths typically occur each year during the summer when water temperatures are warm,” Burge said in a Sept. 10 blog. “The situation is analogous to a human who is infected with herpes and periodically gets cold sores. Normally the virus is latent (present at a low level) and does not cause cold sores. But after a stressful situation, the virus replicates and cold sores emerge. … For oysters, most of the evidence for virus reactivation points to warm summer water conditions.”
According to both Kingzett and Blake, the virus does not affect humans at all but has the potential of destroying an oyster enterprise in only a matter of days when conditions are ripe for its activation.
Kingzett explained Goose Point’s position: “Losing 70 to 90 percent of the oysters in 2,000 acres of beds would wipe us out for at least two or three years if we don’t prepare for it now.”
What can be done
On Sept. 21, Kingzett attended the 71st annual Shellfish Growers Conference and Trade Show in Welches, Oregon, where POBS was a major topic among worried oyster professionals. Disease experts, including Burge and others, discussed their experiences with outbreaks of the virus and shared some strategies to combat the problem.
Breeding programs could be one of the most effective strategies, according to Kingzett. “We (Goose Point) are going to isolate brood stock. We have a hatchery in Hawaii, so our brood stock goes from Willapa Bay over to Hawaii.”
Kingzett went on to explain that Goose Point will be putting seed in other areas of the coast, in case the virus shows up in Washington’s coastal waters. By having broodstock in other areas, they would still be able to supply Willapa Bay with new oysters after an outbreak.
In addition, “I am currently working with two strains of OsHV-1 — the California virus and a microvariant in France — to determine OsHV-1 resistance genes, including a collaboration with the Ifremer station in La Tremblade, France,” Burge said.
She said traditional vaccines don’t work on oysters; their cells can’t “remember,” recognize and destroy specific germs in the ways human cells do. Oysters do possess their own form of immune system that might be stimulated to resist OsHv-1, but scientists aren’t yet sure this will work.
For now, though, “The most effective way to limit damage in new locations from OsHV-1 is to limit its spread,” Burge said. “However, we also want to be ready in case OsHV-1 microvariants spread to the United States. Beyond their cash value and the benefits that oysters provide by filtering water, oyster reefs provide food and habitat for many commercial fish species. Oysters can’t move themselves out of harm’s way, nor can we move all susceptible oysters, so we need to protect them where they grow.”
Kingzett is among Willapa growers ready to take whatever steps are necessary to protect their oysters.
“Nothing has been seen on the West Coast, but we know that the second that it happens, we will go into a whole different level of biosecurity,” he said.
Potential economic impact
Oysters are among Pacific County’s most important economic sectors; the county accounts for most oyster production on the U.S. Pacific Coast. The most recent detailed census of aquaculture in 2013 counted 125 shellfish farms — growing oysters and clams — in Washington producing $149.3 million in sales, compared to 174 farms generating $63.7 million in sales in 2005. Oregon’s 17 shellfish farms generated $10.5 million in sales in 2013, compared to 21 farms and $11.6 million in sales in 2005.
Without identifying where in the U.S. they were grown, the 2013 census said producers of Pacific oysters generated $86.7 million in sales, including $5 million in oyster seed sales. While some other oyster species are grown in Willapa Bay, Pacifics account for the vast majority of income.