The largest oyster aquaculture project ever conducted in the Chesapeake yielded nearly a million oysters this year. But the oysters aren’t headed to the dinner table: They were put in Virginia rivers in the hope that they will produce even more oysters.
The project, launched by the Chesapeake Bay Foundation, started last summer with 1.2 million hatchery oysters bred from several native strains that appeared to have some resistance to oyster diseases.
The results were encouraging: about 930,000 oysters were still alive this summer, said Rob Brumbaugh, a CBF fisheries scientist. “Disease mortality was rather low,” he said.
Of about 500,000 oysters raised from a stock originating in the Lynnhaven River, only about 5 percent died, and many of those were the result of predation by crabs, rather than disease, Brumbaugh said.
Mortalities were in the 10–15 percent range for other oyster stocks, although some originating from the Mobjack Bay lost about 40 percent of their number, apparently after being stricken by MSX.
Evidence in recent years has suggested that oysters which survive the onslaught of the diseases MSX and Dermo can pass that trait on to new generations. In recent years, some of those large oysters have been purchased and concentrated on oyster reefs to help jump-start populations.
But the number of oysters available for such projects has been low. So the CBF, which had originally proposed the Chesapeake 2000 Agreement goal of achieving a tenfold oyster increase Baywide by 2010, launched the hatchery effort with hopes of ratcheting up the number of disease-resistant oysters available.
The oysters were distributed this summer among several restoration sites in Virginia rivers. The hope is that the aquaculture oysters will produce large numbers of larvae “or spat” in the wild, multiplying the effect of the project.
Also, some oysters were placed in two rivers, the Coan and the Wicomico, which suffered heavy losses last year as the result of a brown algae tide that settled in the areas, consuming all of the oxygen on the oyster grounds. “Those are areas that needed jump-starting,” he said. “They shouldn’t be left without oysters for too long.”
Full-size aquaculture oysters are worth about 25 cents each on the wholesale market, so the CBF estimates the market value of the oysters raised at about $250,000.
“Overall, it demonstrates that aquaculture of native oysters is something that could be viable here in the Chesapeake Bay,” Brumbaugh said. He said the CBF plans to raise another 1.2 to 1.3 million oysters this year.