WASHINGTON – A predatory snail that was discovered in the lower Chesapeake Bay last year might cause trouble for the oyster and hard-shell clam industry in Maryland, some marine officials said.
About 200 Rapa whelk — large oyster and clam-eating snails native to Japan — were found last summer in the James River in Virginia, about 100 miles south of the Maryland border.
Scientists said it is too early to predict what effect, if any, the foreign snail will have on bay fisheries, but they said they have to treat the threat seriously.
The Rapa whelk “is thought to have contributed to a declining oyster fishing industry” in the Black Sea after it was introduced there, said Greg Ruiz. He heads a lab at the Smithsonian Environmental Research Center that studies invasive species in coastal areas.
Commerce Undersecretary James Baker, speaking Wednesday at a news conference to outline a federal strategy against invasive species, painted a more colorful picture of the Rapa whelk’s threat.
“This is the kind that will eat oysters and clams. It just sucks them right open,” Baker said, holding up a 6-inch, brown- and-white spiral shell of a Rapa whelk.
“This is very serious problem, particularly for our native oysters,” he said.
The Rapa whelk is believed to have arrived in Virginia’s Hampton Roads area in ballast water on ships arriving from the Black Sea or the eastern Mediterranean.
Scientists think that many of the 160 alien species that have been discovered over time in the bay also arrived in ballast water.
Ruiz said that the size of the Rapa whelks found in the James River last summer indicated that they were in the area for more than a year before they were discovered.
In labs that have studied the Rapa whelk, Ruiz said, the snails are reproducing and eating both clams and oysters. Scientists do not yet know how they act in the bay or if and how they might migrate.
But they fear that the Rapa whelk could move up the bay. If it does, Ruiz said, it would likely colonize on the saltier eastern shore of the bay.
Some fear the snail could then suck the oyster industry dry.
“The Rapa whelk could … prove to be a significant threat to oysters in the bay. If they move upward within it, we could also see it also effecting hard-shell clams,” said Dean Wilkinson of the National Marine Fisheries Service.
“Oyster harvesting has just plummeted in the last 20 to 30 years and diseases are a major, major cause,” Wilkinson said. “Now you throw in [Rapa whelk] and it could potentially exacerbate the problem.”