Deadly clam parasite suspected
|Photo Ann Wood
Shellfish Constable Andy Koch listens to Selectman Helen Miranda Wilson contemplate ways the town can regulate seed purchase with the hope it would prevent future QPX outbreaks.
at second Wellfleet site
QPX appears to be present in
clams at Indian Neck
Shellfish Constable Andy Koch knows what a QPX-infected clam looks like, and it appears that some quahogs growing on an Indian Neck grant are infected with the single-cell parasite.
“You can tell when a clam is weak,” he told the Natural Resource Advisory Board (NRAB) Monday night. “You can definitely tell the difference [between healthy and QPX-infected clams].”
Koch received a call from an Indian Neck aquaculturist who suspected his clams might be diseased after it was announced in December that QPX, or Quahog Parasite Unknown, was killing quahogs on three Egg Island grants. Koch reported that the shellfisherman, who he refused to name, believes that his stock has been infected for three or four years, although it suffered only a small mortality rate. (Koch thinks that’s because the grant is located by a fresh water source which continually washes over the clams. Fresh water kills the parasite on contact.)
This is the second area in Wellfleet harbor suspected of being infected by the parasite that wiped out the clam industries in both Barnstable and Provincetown harbors, among others. QPX infects the soft tissue of the clam, swelling it and making it difficult for the quahog to close its shell, filter food and flush out sand and bacteria. The parasite does not affect humans or any other type of shellfish.
Quahogs, which are mainly marketed as littlenecks, are a popular Wellfleet shellfish second only to oysters. Quahogs account for more than $1 million of Wellfleet’s multimillion dollar aquaculture industry, the largest in the state.
Koch said that he went out to the Indian Neck grant to perform a crude sampling and found some clams that do have the tell-tale signs of QPX, which can include swollen meat, yellow dots or nodules on the meat, chipped shells and meat that retracts from the shell. He took other samples and sent them to Dr. Roxanna Smolowitz of the Marine Biological Lab in Woods Hole for analysis. The presence of QPX in these Indian Neck clams has yet to be confirmed.
“At this point, I don’t want to give any names. It just looks suspicious,” Koch told the Banner Tuesday. When asked whether the stock came from Cape Cod Oyster Co., an Osterville hatchery from which the infected Egg Island clams are believed to have originated, he said, “Some of the stuff has come from the hatchery in question.”
The Indian Neck shellfisherman is following the lead of Egg Island aquaculturists Jim O’Connell, Andy Cummings and Wentzel Ruml, Koch said, and is selling seemingly healthy clams and disposing of the rest.
“He’s doing the responsible thing. He’s digging it out right now,” he said.
The disease seriously infected the Egg Island grants, Koch believes, for a couple of reasons.
“The density issue is a big thing [but] it’s the same class of seed that come from the same hatchery,” he said, adding that QPX is always in the water column. “Without these bad animals introduced in Wellfleet I don’t think the infection would have happened.”
The Shellfish Constable believes that the seed from the nursery, which he didn’t name but has been verified as Cape Cod Oyster, were weak because the hardier northern quahogs were cross-bred with the quick-growing, but weaker, southern quahogs.
“The parasite attacks the weak,” he said.
Koch believes that Cape Cod Oyster bought tiny cross-bred seed from a Maine hatchery rather cheaply and planted them in QPX-infected Barnstable Harbor so that they’d grow larger. The bigger the seed, the more a hatchery can sell it for.
“That’s kind of the operation that was going on. That is the seed that got infected,” he said. “The more you screw around with genetics the faster something’s going to happen….I hate to say it for the poor guys who lost [stock but] if we survive this, it could be a reality guide for more people.”
NRAB members asked Koch whether a town shellfish regulation could be drafted that would restrict if not which hatchery seed is purchased from, the seed’s origin.
“I can’t tell someone not to buy from the [state] certified hatchery,” he said. “It’s like discrimination.”
NRAB member John Riehl suggested that Wellfleet, as the top aquaculture town, could influence the state into creating stricter seed buying regulations. Others thought that density should be regulated; Koch himself thinks that fishermen should not plant more than 75,000 clams per 100 foot run.
But part of the problem, Koch said, is that the state isn’t doing enough to prevent seed from being moved from one site to another. He says that while fishermen need to get permission to move seed, its not physically monitored by the state.
“That’s the problem,” Koch said. “They get that permission but then the state doesn’t come down to watch them take it out of the site.”
Koch did, however, say that the state Division of Marine Fisheries (DMF) is investigating the Egg Island infection.
“The problem is this person who sold these clams [was state certified but] since Barnstable Harbor is infected, he might not be allowed to sell clams past the Barnstable line,” Koch said, and that Cape Cod Oyster may be found liable for that reason.
In fact, when DMF aquatic biologist Mike Hickey announced that Wellfleet Harbor was officially infected with QPX on Dec. 13, he warned that seed grown in the harbor could no longer be sold or transferred to another harbor.
However, Koch said that he met an aquaculturist in Barnstable who grows clams in the parasite-ridden harbor and that he loses only about 5 to 10 percent of his clams, which were purchased at Aquacultural Research Corp. (ARC) in Dennis. Many fishermen in Wellfleet also buy seed from ARC which grows only northern clams.
Meanwhile, fishermen continue to remove clams from the Egg Island – and now Indian Neck – grants, hoping that this will stop the spread of QPX in Wellfleet Harbor.
“I think this summer and fall is going to be the tell-tale sign to where it has spread,” Koch said. “I’m hoping that this is just a little fire we’re going to be putting out. Time will tell.”
Town seeks a third of CPA funds
Miraculous recovery of purse and more in the news