State officials have closed the Damariscotta River’s oyster beds in response to the outbreak of a disease, quarantining infected shellfish to prevent its spread.
Oyster farmers on the river contacted the state with concerns over “extensive mortalities on oyster beds,” said Department of Marine Resources Commissioner George LaPointe on Friday. The state sent oyster samples to Rutgers University for testing, and they came back positive for MSX, an oyster disease caused by the parasite haplosporidium nelsoni.
The state issued an emergency order on Oct. 11 closing the beds.
MSX is not harmful to humans or other sea life, said LaPointe, but the disease can be devastating to oysters.
“It decimated the oyster industry in Chesapeake Bay back in the late ’50s, early ’60s,” LaPointe said. “It’s obviously very serious.”
Maine’s overall shellfish industry — which includes clams, mussels, oysters and scallops — had sales of between $7 million and $9 million last year, according to Sebastian Belle, executive director of the Maine Aquaculture Association. Industry estimates put sales of mussels and oysters at about half the market.
Last year, roughly 3.9 million oysters came out of the Damariscotta, which was about 75 percent of the Maine oyster harvest.
“The oyster industry in the Damariscotta is kind of the epicenter of the oyster industry in the state. It’s where it started, it’s where we have the most farms, the most folks employed,” said Belle. “The emergence of MSX, an exotic disease we don’t have a lot of history with, is a very, very serious development in that river.”
It’s still too early to tell exactly what the impact will be on the oyster fishery in the river, Belle said, but “it looks as though it’s quite significant.”
There are at least 40 to 50 people directly employed in oyster farming on the Damariscotta, said Belle. Indirectly, hundreds more jobs are supported in trucking, processing and other areas, he said.
Belle noted that Maine oysters are “identified in the gourmet foodie world as being the best oyster in the marketplace.” He wasn’t worried that the outbreak would affect that reputation, but was concerned that Maine oyster farmers may have difficulty meeting market demand.
Paul Rawson, professor of marine science at the University of Maine, said that a number of the oyster farmers on the river eke out a living that may be jeopardized by the outbreak.
“What it’s going to do is cause severe stress to the farmers who may suffer serious crop loss,” said Rawson. “If you’ve got some farms where the profit margin isn’t that great, this is a significant problem.”
The disease tends to hit larger oysters that are close to market size, said Rawson. So farmers have invested at least two years to try to get them ready for market, and then they die off, he said.
There have been limited incidences of MSX in Maine waters, said LaPointe. There have been a few possible cases in the Piscataqua River and in the Damariscotta in the mid-1980s, he said.
The state is investigating the outbreak trying to figure out just how extensive it is and to determine how the parasite came to Maine waters, LaPointe said.
“Our first priority right now is to understand the extent of the outbreak and how to control it as best possible,” he said.
Rawson said studies in other areas have shown the parasites don’t survive well in low-salinity waters, so oysters could sometimes be saved by moving them to more brackish areas.
But the Damariscotta River oysters must be kept in the river, he said, and the entire river is highly salinated, so that’s not an option.
Belle said the oyster growers are taking the outbreak “extremely seriously” and have met among themselves and with the state to determine how to manage the disease.
They’re looking into what has been done in other parts of the country and world to deal with outbreaks, he said.
“It’s not the first time we’ve dealt with a disease challenge,” said Belle. “I’m confident in our growers. They’re some of the most creative, proactive growers in the world.”