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Photos Ann Wood
Shellfisherman Molly Benjamin lost a grant full of clams to QPX in Provincetown in 1995 — she’s hoping that won’t happen to her Wellfleet batch. |
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Dr. Roxanne Smolowitz shows shellfishermen how hard shell clams react to QPX, or Quahog Parasite Unknown, a single-cell parasite that often causes profound mortality rates in quahogs. |
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Parasite threatens
Wellfleet clam industry
Scientists confirm presence of QPX, former scourge of Provincetown
Ann Wood
Banner Staff
They were the words no one wanted to hear.
“As far as we’re concerned, Wellfleet Harbor now has QPX,” Mike Hickey, aquatic biologist for the state Division of Marine Fisheries, announced Monday. “This has been ongoing for awhile. This just hasn’t happened a month ago.”
QPX, or Quahog Parasite Unknown, is a disease caused by a single-cell protistan parasite that infects quahogs, or hard shell clams, and causes them to weaken and die when they are about two years old. It spreads like a virus — from infected clam to infantile clam. The denser the clam bed, whether it is wild or cultured, the faster QPX spreads.
“It’s like putting a kid with the flu inside a room with kids without the flu. Give them time and it will spread,” said shellfish pathologist and researcher Dr. Roxanne Smolowitz of the Marine Biological Lab in Woods Hole.
The parasite does not affect humans or other shellfish such as oysters, soft shell clams or mussels. Clams infected by QPX are safe to eat.
In a cramped room in the Wellfleet Senior Center, more than 50 normally outspoken shellfishermen reacted to the news with stunned silence. Longtime fishermen figured this could be the end of littlenecks in Wellfleet Harbor – a popular shellfish second only to oysters. After all, the parasite wiped out Provincetown’s growing clam industry in 1995 and Barnstable Harbor’s clam beds in 2001.
Simply put, QPX infects the soft tissue of the clam, making it difficult for a clam to close its shell. Therefore, it can’t filter food or flush out sand and bacteria and death is often caused by secondary infections.
Quahogs accounted for more than $1.1 million of Wellfleet’s $3.6 million aquaculture industry in 2002. Wellfleet is the top aquaculture, or shellfish farming, town in the state.
The announcement came after shellfish experts headed out to three shellfish grants on Egg Island Thursday afternoon, to take laboratory samples and perform “crude tests” on quahogs which fishermen worried were diseased because of profound die off.
The “crude test” consisted of opening up “a bunch of animals,” said Bill Walton, Barnstable County Cooperative Extension’s aquaculture specialist and Wellfleet’s last Shellfish Constable. Many of the clams had tell-tale signs of QPX, he said, including nodules that look like pimples, chipped shells, meat retracted from the shell and dead clams. Infected clams are often swollen and sometimes have yellow dots present on the tissue, Smolowitz added. While clams bury themselves in sand, QPX-infected animals often come to the surface to die, or are eaten by crabs or seagulls there.
“Sure enough, on all three sites people had concerns [with], it did look like the disease was there,” Walton said, and praised aquaculturists Jim O’Connell, Wentzel Ruml and Andrew Cummings for coming forward. “You can not begin to solve this unless you have an idea of where you are sure it is.”
And there is a plan to rid the harbor of QPX, albeit an experimental one.
Both Walton and Smolowitz said that fishermen should get the infected stock out of the water right away.
“I would recommend that if you can get these clams out it is to your advantage,” Walton said, and added, “I can’t guarantee that it hasn’t already spread.”
But experts expect the harbor will be better off if the infected animals are removed. Smolowitz said that older clams — those closing in on the marketable age of three years — are more heavily infected with QPX than younger clams that have just contracted the parasite.
“The more QPX you’ve got in the water the more likely your next door neighbor’s going to get it,” she said.
While three Egg Island grants are heavily infected by QPX, Smolowitz said that some clams on the outskirts of those grants are infected, but to a lesser extent.
Because cold weather has set in, shellfish experts say clams are somewhat dormant; they eat less and are therefore ingesting less water and QPX.
“We think that there’s very little infecting going on right now,” Smolowitz said. “So if we get stuff out and [the harbor] flushes and flushes and flushes then we hope it flushes [the QPX] right out.”
Cold water also keeps the parasite somewhat at bay, experts believe.
“That’s one thing we have in our favor at this point. There’s time to think about this and decide what to do in this harbor,” Walton said.
But Shellfish Constable Andy Koch has already decided what to do. He wants the sick animals removed. Now.
“I think the quickest thing we can do is get as many volunteers as possible out there to clean it up,” he said, adding that the town will provide a dumpster and the town landfill has agreed to accept the infected clams. He estimates that there are somewhat less than 1.5 million clams that must be removed in 15 or 16 100-foot runs.
Koch even has a plan to use a Bobcat and other mechanical devices to try and remove the clams should ice set in.
“Whether its going to work or not, I don’t know,” he said, adding that if that doesn’t work, removal will continue as soon as the ice melts. “If we get 80 percent [of the clams] out, we’re way better off.”
As long as the water is cold, the parasite will remain at bay and the work can resume in the spring, Walton said.
“Please don’t give up hope if it ices midway through this,” he said.
Just because the clams are removed, Smolowitz says fishermen shouldn’t assume the area is QPX-free.
“I recommend that when you pull your clams out you grow oysters for a year or two,” she said.
Smolowitz emphasized that after working on the flats, especially after working Egg Island, fishermen should rinse every piece of clothing and gear with fresh water, which immediately kills the saline-dependant parasite. That will prevent QPX from spreading to other parts of the harbor, she said.
Barbara Austin, who has about 4.5 million clams planted on Indian Neck (and is also a member of the Wellfleet Shellfish Company, a cooperative which has been heavily promoting the town’s littlenecks), says she’s not too worried just yet because her grant is so far from Egg Island.
“I’m hopeful. I’m just glad that the growers who are affected are willing to do something about it because the trickle down effect is phenomenal,” she said, and then added, “We’re all stressed.”
Molly Benjamin, who has about a million clams on a grant she’s working with Keith Rose, has been through this before. She was the chair of Provincetown’s Shellfish Committee when QPX wiped out the clams in its harbor.
“Of course I’m [worried]. I mean in Provincetown, I think I said, it was like smallpox in an Indian village. But there was such a gap in figuring out what it was [that this situation is different],” she said.
When QPX struck in Provincetown, it wiped out both the wild and cultivated clams in the harbor. As Benjamin told the Banner in 1997,“Growing hard clams here is just not viable, it’s over.” She added, “In Wellfleet people make $40,000 to $100,000 a year while down here we’re losing our shirts. People have sunk tens of thousands of dollars out of their own pockets and their hopes and dreams into their grants. Two towns away, they’re producing fine.”
Seven years later, things are no longer fine in Wellfleet. And the state wants to know why.
“So we can prevent this sort of thing from happening and getting worse,” Hinkey said. “The other thing we need to determine is how it got here, when it got here.”
Some people think they have the answer: clam seed.
Walton said that the problem is that the seed (small clams growers buy from hatcheries, or nurseries, and plant on their acreage) was grown out in QPX-infected Barnstable Harbor.
“It was strongly suggested this was a problem of transferred [seed] from one harbor to the other,” Walton said. “In this case, we have a clear record of them being in Barnstable Harbor, which is infected.”
Dick Kraus, one of the owners of Aquacultural Research Corp. in Dennis, a shellfish nursery which has a bed in Wellfleet harbor, believes there’s a bad genetic component to the seed Egg Island grant-holders planted.
“The point is that Jim [O’Connell] and a couple other guys brought in some seed, they didn’t know,” he said. “It could just as well be infected and have a genetic component.”
While there is a genetic difference between seed originating in different areas of the Eastern seaboard, northern hatcheries aren’t allowed to grow seed from clams that originate in the south. Clams from Massachusetts are hardier and more resistant to QPX than Southern clams, Smolowitz said, and added that when Southern clams are placed in Northern waters, they more easily contract the parasite (which is believed to be always present in the water) and pass it on to the hardier northern clams.
Smolowitz doesn’t think the Egg Island infected clams are the result of hatchery-infected seed.
“We have never really identified it in nursery stock,” she said. “There seems to be a strain effect from where you are and where [the seed] comes from.” While it was not recommended that growers buy clam seed south of New Jersey, Smolowitz is no longer recommending that seed be bought from as far south as New Jersey.
Kraus said that he’s been suspicious of Cape Cod Oyster Co., an Osterville hatchery from which the Egg Island seed originated, for awhile. “Oh, yeah, it’s been going on in Barnstable for a long time,” he said.
But no matter where the parasite originated, experts agree that the most important thing is to try and stop the spread of QPX before it ruins Wellfleet’s clam industry.
“Let’s just say, from this point on tonight, we’re digging stuff out,” said Koch.
Anyone who would like to volunteer to help clean up Egg Island should call the Shellfish Dept. at (508) 349-0325.
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