The Virginian-Pilot (Norfolk, VA)
A type of predator sea snail accidentally dumped into the Chesapeake Bay is breeding, is more widespread than expected, and could pose real problems for shellfish stocks in the Bay, scientists reported Monday. The veined rapa whelk, native to the Sea of Japan, has been found at 19 locations so far in the lower Bay, including the Elizabeth River and along Ocean View beaches in Norfolk, and has the potential to move up the James River toward some of the best seed oyster beds left in Virginia, the scientists said.
The whelks, each about the size of a softball, prey on clams and oysters and are voracious eaters. Over about 20 years, for example, they nearly wiped out oyster stocks throughout the Black Sea, where Russian officials could do little but watch, said Yuri Kantor, a marine biologist visiting here from the Russian Academy of Science.
"There now is wide acceptance that we probably have a reasonable population" of Asian whelks in state waters, said Roger Mann, a shellfish expert at the Virginia Institute of Marine Science, which hosted a briefing Monday for top state officials, seafood merchants and fishery scientists.
John Paul Woodley Jr., Virginia's secretary of natural resources, called the meeting to hear what biologists have learned five weeks after confirming the first rapa whelk ever found in American waters. VIMS researchers stumbled on that whelk while trawling in the lower James River, near the Monitor-Merrimac Memorial Bridge-Tunnel.
"While little is yet known about this animal's possible impacts on the Bay ecosystem," Woodley said, "it could have a significant impact on Virginia's shellfish industry," which already is struggling from other threats.
As with other foreign species that have entered the Chesapeake Bay, the whelk likely got to Virginia in ballast water aboard a trans-Atlantic cargo ship, experts agree.
The theory makes even more sense considering that the ports of Hampton Roads receive more ballast water, which stabilizes ships during ocean crossings, than any port on the East Coast outside of New Orleans, said Greg Ruiz, who studies ecological threats posed by ballast water at the Smithsonian Estuarine Research Laboratory near Annapolis, Md.
Ruiz pointed out that 159 other foreign species are known to have invaded the Chesapeake Bay, and that about 25 percent have made a significant dent in the ecosystem.
Among the most notorious are hydroids, an algae-like animal that clogs underwater utility lines, and a parasite known as MSX, which has ravaged oyster stocks in Virginia and Maryland.
Mann said commercial fishermen have reported finding numerous whelk
egg cases, like small pea pods, from the James River to
As in the Black Sea, whelks here have few natural predators. Blue crabs and large fish may gobble some whelk larvae, but the sea snails grow too big too fast to succumb to such threats.
Rapa whelks are harvested for their meat and shells in Korea; indeed, they are considered overfished there. While smaller, native whelks also are caught by Virginia fishermen, it remains unclear if markets would support a rapa whelk fishery, too. Or whether Americans would take to the larger species as a seafood.
One idea for better researching and controlling the whelks is putting a bounty on them. Mann said he hopes to find money to pay fishermen to turn over rapa whelks captured on the water.
One waterman dredging for crabs during the winter discovered a whelk stuck in the teeth of his steel dredge. That causes Mann some concern, he said, because it shows the whelk is capable of burrowing in the mud to survive cold winter temperatures - a trick they also use in Korean waters.
"It's actually quite a nasty snail," said Kantor, of the Russian Academy
of Science. "And it seems to be very, very hungry, as we've witnessed on
the Black Sea."