Updated on October 31, 2011
In many places where oysters once thrived, baby oysters are missing something that they need in order to grow: the shells of their ancestors.
I know it sounds sort of romantic or symbolic, but it is literally the case that when baby oysters are in their larval stage – at about two weeks of age – they need to attach themselves to some kind of substrate, in this case a piece of shell, so that they can settle down and go about the business of growing. “They stay on that substrate for life,” explains Karen Rivara of Peconic Pearls.
Here’s a video in which Rivara, owner of Aeros Cultured Oyster Company and secretary of the Noank Aquaculture Cooperative, describes the nuts and bolts of oyster farming and all the things that oysters need to grow successfully:
The pieces of shell are necessary to keep the baby oysters from being enveloped by the muddy bottom of the sea floor, which kills them. Technically, it doesn’t have to be shells from oysters, but it has to be a shell that’s sturdy enough and big enough to rest on the surface of the sea floor without sinking in. Mussel shells, for example, are too thin, light, brittle, and small. Big clam shells will suffice, but the best choice of all is oyster shell. It seems like finding old shells shouldn’t be that big of a deal. I mean, how hard can it be for a baby oyster to find a nice piece of broken shell to call home?
Pretty hard, it turns out! Oyster populations have fallen in many places where there just aren’t enough shells left on the sea floor to support a healthy community. “A lack of oyster shells is a limiting factor in the restoration of oyster populations,” explains Betsy Peabody, founder and executive director of the Puget Sound Restoration Fund. She and her staff have set about bringing cast off oyster shells to the places where Olympia oysters, native to the area, are growing but not thriving.
Several different factors have contributed to the decimation of oyster populations. The lack of shells is due to a combination of factors: over-harvesting, habitat destruction, poor water quality and, in some places, turbulence from the wakes of motor boats. I asked Peabody if acidification was playing any role in damaging the oyster population. She said that there is a two year monitoring program in place and that they do see chemical changes in the water in Puget Sound– low ph – and they also observed some larval mortality. They don’t yet know, however, what the biological responses to these changes will be.
There are many benefits to restoring oyster populations to health – environmental, nutritional, and cultural. Oysters are filter feeders, meaning that the fact that they filter algae out of the water in order to eat it has the beneficial side effect of cleaning excess algae out of the water. Many communities are experiencing trouble with an excess of algae in their local body of water and some are contemplating building expensive sewage systems to deal with the problem, but in Wellfleet, Massachusetts, they are contemplating addressing the problem by restoring oyster populations instead. In “Oysters to the Rescue,” an article in Wicked Local/Wellfleet, Curt Felix, founder of Plankton Power, Inc., stated that sewers “cost about $500 to $1,000 per pound of nitrogen removed. If you look at natural systems, in particular oysters, you can do the same removal for about $5 a pound.” Oyster beds can also help to fight the effects of erosion by building up the shoreline.
For the tribes native to the Puget Sound area – Suquamish, SquaxinIsland, Port Gamble S’Klallam, Skokomish, and Jamestown S’klallam – restoring the oysters would provide them with a highly nutritious food that is part of their traditional diet. If the restoration efforts make it possible to grow enough oysters, they might have enough to conduct a ceremonial harvest.
So, how to address this problem? Clearly, there are shells out there. Look in the kitchen of any seafood restaurant at the end of the night. A lot of shells are currently entering the waste stream rather than being recycled and brought back to the shore to support the next generation of oysters. Peabody and her crew – and those involved in similar programs across the country (see below) – are working with restaurants to collect the empty shells generated when they serve oysters to customers.
I asked Robert Spaulding, executive chef at Elliot’s Oyster House in Seattle, to tell me about how his restaurant participates in the shell recycling process:
“We collect the shells in a garbage can and put them into a dumpster designated specifically for them. They are not refrigerated, however they are picked up three times a week. This effort has been organized at a grass roots level and is all about creating value for those involved. There is value in that many of the people who will be donating shell will not have to pay for that shell to be removed from the premises as they would if it were regular garbage. There is PR value in involvement and there is long term reward in a continued and strengthened supply of shellfish and the environment to support that supply. There is value in it for them because they can show they are doing something positive for the environment with small investment in space and resources. Then it’s a matter of engaging other restaurants and oyster processors/farmers. Show them the value and create buy-in.”
When I asked him if patrons expressed interest in the afterlives of the oyster shells he said:
“Patrons definitely express interest. We have guests ask about what we do with the shells all the time. We do let them know what happens to the shells and in fact get a lot of positive response. Our shuckers and service staff are educated in what is done with the shell as well as to the importance of the oyster as an integral part of the marine habitat. They relate this to our guests when it seem appropriate in their conversation.”
An important – and necessary – part of the process is that the shells must be set aside to cure for an extended period before being returned to the water. This is done so that any disease-carrying substances that may be on the shell will have expired and cannot contaminate the oyster bed. In some places the shells are left to cure for six months whereas in other places they are left to cure for 18 months. In short, don’t toss freshly shucked shells into the water.
There are many oyster shell recycling programs all over the United States. We are putting together a list. If you know of one, please email us at [email protected].
Here is a partial list of oyster recycling programs:
The Oyster Reef Restoration Project in the Indian River Lagoon, co-sponsored by Brevard Zoo and the Nature Conservancy, in Central Florida
– Roz Cummins