For nearly a century, oysters have been pummeled from two sides: us and nature. Our appetite for oysters has spurred overharvesting; at the same time, pollution has made oysters more vulnerable to disease, and sediment has smothered oyster beds. Conservationists, lawmakers and natural resource experts have been scratching their heads for nearly as long, trying to figure out how to save Crassostrea virginica populations. Now, solutions that give us hope are coming from us — and nature.
The two states that contain the Chesapeake Bay — Maryland and Virginia — are both encouraging shellfish aquaculture as a way to ease the pressure on native wild oyster populations. Increasing aquaculture makes sense for watermen, too. When they grow their own shellfish, they can depend on their catch more readily than can those who dredge wild oysters.
Virginia has for years encouraged oyster farming. Its shellfish aquaculture is a multimillion-dollar industry, and the Virginia Marine Resources Commission recently approved the creation of 15 new "aquaculture opportunity zones" in hard-bottom, clean, shallow waters.
Maryland's government, which has been slower to champion oyster farming, recently rolled out fiscal support to take the pressure off native oysters. Maryland has offered $2.2 million in grants in a new shellfish aquaculture loan program, with hopes of getting more watermen and entrepreneurs into shellfish aquaculture.
At the same time, nature is making adjustments. Beneath their rock-like shells, oysters have begun to develop resistance to diseases such as MSX and Dermo, which have plagued populations for the last 50 years, according to a 2010 Chesapeake Bay Foundation report.
Through natural selection, disease-resistant oysters are surviving longer to produce disease-resistant offspring. A decade ago, more than half of the oysters in Virginia's York River were dying from MSX; today, less than 5 percent of oysters die from the disease, according to the report. In Maryland, the Department of Natural Resources reports that disease-related oyster mortality fell to an average of 17 percent annually from 2005 through 2009, down from an average of 29 percent in 1985 through 2004.
In addition to oyster farming and resistance to disease, wild native populations are getting even more help from restoration projects conducted by groups and individuals that raise oysters off docks and from large-scale efforts. For instance, Horn Point Laboratory, on the Eastern Shore near Cambridge, has a setting facility capable of producing 2 billion oysters each year. The facility is the largest Eastern oyster hatchery in the world. Other groups are rebuilding oyster reefs, making sure wild oysters have hard surfaces — such as oyster shell, repurposed concrete or other materials — to attach to. Plus, ongoing research on oysters and oyster communities has taught us better ways to rehabilitate oyster beds.
For these efforts, we get a twofold return: Not only will there be more oysters available for the harvest, but more oysters means cleaner water: One adult oyster can filter as much as 50 gallons of water a day. So restoring native oyster populations through aquaculture and sanctuaries not only increases the number of harvestable oysters, it rebuilds important bay-bottom ecosystems where small fish and other marine life thrive, and creates a strong natural filtering system for sediment, excess nutrients and chemical contaminants.
These developments offer us glimmers of hope for cleaner bay waters and flourishing oysters, but we're not out of murky waters yet. Wild and farmed oysters alike still face the threat of siltation — which slows filtration and covers suitable substrate for spat to latch on to. And new challenges are emerging: A 2010 study from the University of Maryland's Center for Environmental Science found that increasing acidity and the shifting of other water parameters are causing oysters' shells to grow thinner, leaving them more vulnerable to crab predation.
So while we need to continue to build the oyster ranks in bay waters, we also need to get serious about cutting the pollution that drains into Chesapeake waters — by curbing storm water runoff, enforcing laws and denying damaging construction projects. We'll also need to invest in more eco-friendly alternatives for salting roads, maintaining landscapes and raising livestock. Individuals in both urban/suburban areas and rural farms will need to consider how individual actions can multiply when millions make a change.
We needn't worry much about a future bay without oysters. Oysters are tough mollusks — having survived as a species for 200 million years — and with help from watermen, oyster farmers, legislators, conservationists and others, there are plenty of reasons for hope.
Carrie Madren writes about environmental issues, Chesapeake life and sustainable living. She lives in Olney. This article is distributed by Bay Journal News Service.