By DOREEN LEGGETT
STAFF WRITER THE CAPE CODDER
ORLEANS — It was only a few short years ago that Provincetown earned the unwelcome distinction of being the first place in the United States with the shellfish disease QPX. Precautions were taken across the Cape and across the state, but " quahog parasite unknown, " which only affects its namesake, has reared its ugly head again. This time in Pleasant Bay.
" Pleasant Bay is the next real outbreak, " said Roxanna Smolowitz, a veterinarian and pathologist at the Marine Biological Laboratory in Woods Hole, who has been studying the disease. " I don’t know why it is in Pleasant Bay where we haven’t seen it before. " She said that the disease was bad news when it turned up in Provincetown grants and in Duxbury’s wild fishery, but she is not prophesizing gloom and doom for the bay yet. " I think we are going to have to ride with this awhile, " she said. Smolowitz added that as the weather heats up, the extent of the outbreak will become clearer.
Dawson Farber, Orleans’ shellfish constable, said that in April it was discovered that quahogs on one of the aquaculture grants in Pleasant Bay, south of Barley Neck, were infected with the disease. That number has jumped to three grants. Farber wants to make it clear that QPX does not affect humans. Unlike red tide, which is an algae that can make shellfish poisonous to warm-blooded animals and has caused the closure of the Nauset Estuary, QPX only affects quahogs. " There is no impact to humans [if they consume it], " he said. " Bold that, underline it, put 10 exclamation points after it. Whatever it takes to get that across. "
Although it doesn’t affect human health – QPX can affect livelihoods. The aquaculture industry in the bay (there are more than 20 grants) can bring in up to $750,000 a year, and the wild fishery can bring in close to half a million dollars. Those figures do not include the money the town gets from selling recreational and commercial shellfish permits. The disease wreaked havoc on the Provincetown flats in the early ’90s and sent scientists scrambling to the labs. Signs of QPX – slightly open shells – usually appear when the animals are just about market size.
" It is a slow-growing disease, " said Smolowitz. " You start to see mortality in the fall or the spring. " In 1995, Provincetown had recently turned to aquaculture to help a population that saw a 50 percent unemployment rate in the off-season. Almost all of the town’s 35 grants were affected. " Most people have quit down there, " said Smolowitz. She added that if they start up again it is likely the disease will come back. Scientists are trying to address the problem by developing a strain of quahogs that are resistant to the disease.
In 1995, that attention transformed the X into a known entity: it is the protist Labyrianthomorpha. Smolowitz said that she and others have shown that QPX is transmitted by direct infection, quahog to quahog, and grows well in warm (around 72 degrees) salty water. " Basically, it likes warm weather in the sea, " she said.
Smolowitz said that it isn’t clear whether QPX was in the water and certain parameters triggered it, or if was brought in from another area. Orleans has tight regulations about not planting seed from other water bodies in its waters. " The problem is there is so little known about the disease, " said Farber.
Peter Ho, who has a grant in the bay, said that in the past couple of years there have been die-offs of quahogs that seemed inexplicable at the time, but could have been QPX. " I feel that it’s been in the bay all this time, " he said, adding that its effects have been spotty at best. At the same time, Ho said, the quahogs in Pleasant Bay have grown slower and had higher mortality than other areas so it could be lack of food or even the water conditions. " People have seen different things happen to their animals, " he said. " Pleasant Bay has been an enigma for quahogs in general. No one understands all the factors. " Ho said some are frightened of the publicity QPX will generate, but he doesn’t intend to do anything differently. He’ll take his quahogs to market just the same. " It doesn’t affect human beings, " Ho said, adding that some quahogs can live through mild cases [of the disease] and still can be sold. QPX has not been found on Ho’s grant. What the continuing issues with quahogs may prompt is growers looking at different types of shellfish, he said. Fishermen are very adaptable. " I have more interest in steamers, " he said.