Chesapeake Bay oysters appear to be gaining more resistance to diseases that have caused their numbers to decline in recent years, and states should expand sanctuaries that allow resilient oyster populations to expand, according to a report released Tuesday by the Chesapeake Bay Foundation.
In Maryland, the report said, recently released state data shows average annual mortality from the disease MSX fell to 17 percent between 2005 and 2009, from 29 percent between 1985 and 2004. And in Virginia's York River, fewer than 5 percent of oysters are dying from MSX, down from more than half a decade ago.
Many disease resistant oyster are currently being harvested, but disease resistance will increase if they are allowed to repopulate on reefs placed off-limits to harvesting, the report says.
"Nature seems to be doing its part, and scientists and state policymakers can help by restoring and protecting more historical oyster reefs," CBF president Will Baker said.
He added that oysters can make the same comeback that has been seen with blue crabs, whose dwindling numbers have rebounded in the wake of severe harvest restrictions.
The report, which also calls for increasing oyster sanctuaries, reef building and anti-poaching efforts, is based on a review of recent research, state data from Maryland and Virginia and interviews with oyster experts.
The report calls for placing 40 percent of historical oyster grounds off limits. Maryland's oyster restoration plan released in May calls for declaring 25 percent of oyster reefs as sanctuaries, a proposal that has prompted complaints from watermen that it will drive them out of business.
Besides sanctuaries, the authors also support the increased emphasis in Maryland and Virginia on oyster aquaculture. The report said Virginia is ahead of Maryland in promoting oyster aquaculture, noting the number of farmed oysters has increased tenfold in three years in Virginia to nearly 10 million with a market value of $2.8 million.