Hidden History - Bring Back Bivalves
Several organizations are working to restore the oyster populations of yesteryear in the Chesapeake Bay
By Ben Swenson
Its hard to imagine the Chesapeake Bay of the 17th century, an estuary teeming with marine life so thick that Captain John Smith once tried to catch fish with a frying pan. Weve come a long way since thenand regrettably, thats a long way down. There are several efforts underway to reverse the decades-long degradation of the Bay (see last months Hidden History column about the Captain John Smith Chesapeake National Historic Trail), but if were ever going to see anything remotely approximating John Smiths Chesapeake Bay, theres one animal that must be part of that equation: the Eastern Oyster.
John Smith noted in his journals that oysters in the Chesapeake Bay lay as thick as stones, their reefs so numerous and imposing that they broke the waters surface and made navigation difficult. But overfishing, pollution and diseasestwo in particular, MSX and Dermohave ravaged oyster populations. Scientists now estimate that the number of oysters in the Bay is about one percent of historic levels, meaning that the few days that it used to take oysters to filter all of the water in the Bay has turned into a year or more.
Within the past several years, there have been important developments in efforts to restore oyster populations in the Bay. Several organizations are invested in itthe Virginia Marine Resources Commission, the U.S. Army Corps of Engineers, the Chesapeake Bay Foundationas well as private individuals and businesses interested in consuming and selling the tasty bivalve. The efforts at oyster restoration thus far have had mixed results but are showing encouraging signs and producing valuable insight on how to proceed in the future.
When I spoke with Tommy Leggett, an oyster restoration and fisheries scientist with the Chesapeake Bay Foundation (CBF), he was on his way to Charlottesville to collect the remains from an oyster roast100 bushels of shells, he figured. Leggett and his colleagues use discarded oyster shells like these, as well as others he collects from restaurants around the region, to rebuild oyster reefs in the Bay. Theyll plant spat, or baby oysters, on these shells and use these implanted shells to create reefs in the water. Putting the spat on larger oyster shells is critical, since it affords protection against predators, a lesson learned the hard way several years ago when cownose rays made quick work of 750,000 baby oysters the CBF had planted on a reef but not attached, or clutched, to larger shells.
Having a hard surface on which the spat can attach, raised at least a couple feet out of the smothering silt, is critical for oyster reef survival. But there simply isnt enough old, discarded shell to go around. Too much of it has been lost in the past. That was the thinking behind dozens of so-called reef balls that Leggett and a handful of volunteers lowered into Norfolks Lafayette River last summer. The reef balls are thigh-high concrete domes, hollowed out with polka dot-like holes around the outside.
When the reef balls went into the river last summer, there were fingernail-sized oysters already implanted on them. Leggett has been back to monitor their progress, and its been quite successful. The oysters, in just one year, have grown to more than an inch-and-a-half. This summer theyre sexually mature, meaning that the spawn on the reef balls this year is, as Leggett describes it, one giant love fest.
Will the oysters ever be as plentiful as in John Smiths Chesapeake Bay? Leggett says thats not realistic, but perhaps 50 percent of that is an achievable goal. So much of the habitat has been degraded and lost, says Leggett. So much depends on society and how we move forward.
Meanwhile, there are hopeful signs that oyster restoration is working. There are now dozens of new reefs around the Bay and its tributariesYork River and Lynnhaven River for instance, where wild oyster populations are starting to return. Scientists are cautiously optimistic, too, that oysters, through the process of natural selection, appear to be developing resistance to diseases.
Theres no book on oyster restoration, says Leggett. It wont happen overnight. He and fellow scientists will continue to adapt their methods, learn from their successes and mistakes, and move forward, one oyster roast at a time.