Shucks! Don't pitch those oyster shells
Recycled shell can be used as a habitat for new oyster production, which has been impacted by parasites and other issues in Delaware waterways
- In the 1880s, the oyster commercial harvest in Delaware Bay reached a peak of 2.4 million.
- Scientists in Delaware and Chesapeake are working to fix the oyster habitat disappearing.
- Some eateries also are recycling the shell.
In the oyster food chain, people are the broken link: We harvest them. We eat them. We pitch the shells in the trash or maybe in the driveway. Long ago, Native Americans piled them high at Cape Henlopen to form shell middens.
Generations of oyster slurpers spread the shell, called shucks, across the landscape. Most never made it back to Delaware Bay
And that was bad for oysters. Scientists now know that the filter-feeding bivalves depend on oyster shell as a habitat for the new oyster production.
"Oyster shell is not a pretty thing," said Joe Casey, a Rehoboth Beach-based shell recycler.
The shell is heavy. It smells, and flies and their babies — maggots — munch away at the residue. To recycle shell is hard work and includes collecting it, washing it and allowing it to cure. Curing makes the shell pathogen free.
But Casey believes everyone should be recycling oyster shell because it is so important to oyster reproduction.
"Everyone likes oysters, to eat them is very chic," he said. "They should be invested" in where they come from.
Oyster shell is a sideline for Casey. His company, Clean Green Horizons, specializes in converting used cooking oil and fats into bio-diesel. Since 2009, he's collected over 3.5 million pounds of the stuff from area restaurants.
A few years back, he added oyster shell recycling to the mix after he was contacted by the Maryland-based Oyster Recovery Project. Back then, he collected the shell from area restaurants and it was taken to the University of Maryland's Horn Point Lab in Cambridge, where it was used to build new oyster habitat in Chesapeake Bay.
Now, he's on his own, collecting the shell and stockpiling it at a yard in Harbeson. One day, he said, he hopes it will create new habitat in Delaware waters.
That could be critical to future oyster reproduction in the state.
Earlier this year, a state assessment of Delaware Bay Oyster Beds found that oyster production was way off. This year's harvest quota is set at 10,661 bushels and is the lowest since 2003.
The reason, said Richard Wong, a state shellfish biologist, is that young oysters, called spat, haven't been settling onto oyster beds where they can eventually grow to market-size oysters. Low spat numbers mean fewer market-size oysters in the future.
It's been "five years in a row now of very bad spat recruitment," Wong said.
No one is sure why spat recruitment is low, he said. But one thing scientists do know is that healthy oyster reefs stay healthy with the infusion of shell. Over time, oysters can build massive reefs, which become important not just for oysters but for other fish species.
Oysters are considered a keystone species in the Delaware Bay because the huge biomass of shell contributes to spawning and nursery areas for other fisheries. Oysters are also important for water quality. They feed by filtering the water around them, drawing out tiny particulates and nutrients. The water they pump out is cleaner than what they draw in.
Wong said that Delaware Bay oysters, historically, have been a huge economic driver throughout the region.
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In the 1880s, the commercial harvest in Delaware Bay reached a peak of 2.4 million bushels a year and Delaware Bay oysters – both canned and on the half-shell – were widely sought. They were called "white gold" because they were so valuable.
By the late 1800s, fishermen in sailboats harvested oysters commercially, using oyster tongs to lift the shellfish from the bottom.
Later, they used dredges to harvest the shellfish faster and more efficiently and then, after World War II, the Delaware Bay watermen cut the masts off their schooners and repowered with engines.
By the early 1950s, millions of pounds of oyster meat — each bushel yields about 7 pounds of meat — were harvested in Delaware Bay.
From 1947 to 1958, there were tremendous harvests and then in 1959, the bottom fell out. That year, when commercial fishermen went out to their leased oyster beds, discovered dead and dying oysters by the score.
In one account, a commercial oysterman from New Jersey took two scientists out for a Labor Day party. As they pulled up oysters, they discovered empty shells and partially opened shells with the rotting oyster meat oozing out.
The mortality was massive — 90 percent to 95 percent in the planted beds and 50 percent in the less-saline seed beds farther up the bay.
The cause of death: a microscopic protozoan parasite named MSX.
Two years later, it hit the Chesapeake Bay. From 1947 to 1958, Delaware oyster harvests ranged from 571,000 bushels to 285,000 bushels. In 1959, the harvest dropped to 41,000 bushels.
Over time, oysters slowly developed some immunity to the parasite and by the 1970s, the stock rebounded for a 30,000 bushel harvest from the Delaware beds in Delaware Bay.
Then, a second parasite — Dermo — hit the Delaware estuary. In 1985, the harvest dropped to 5,611 bushels.
Both parasites are deadly to oysters, but they don't harm people. An infected oyster that isn't dead is still a top-quality oyster — if it can grow to market size.
In the meantime, scientists working in both Delaware and Chesapeake bay realized that oyster habitat was disappearing. Similar restoration efforts are underway in places like New Hampshire and around the Gulf of Mexico.
Oyster larvae are free swimming in the early stages of life but within a short period, they need a hard, clean surface to make a permanent home. As oysters are harvested, shell is removed. Putting back new shell maintains the beds, creating oyster habitat.
The U.S. Army Corps of Engineers, working with officials in Delaware and New Jersey, set out to improve oyster habitat with a shell-planting project that began in July 2005.
Between then and the summer of 2008, the corps spent $4.9 million in federal dollars on the project. State and local agencies came up with $1.6 million.
Well over 1 million bushels of shell — called "cultch" — were planted in critical areas of the bay.
But Barbara Conlon, the corps biologist who managed the project, said they had great difficulty finding oyster shell for the restoration project and actually considered shipping tons of shell from Connecticut by rail car. Much of the oyster shell was going to the Chesapeake for a massive restoration effort there.
In the end, Conlon said, they used a mixture of surf clams with some oyster shell added in.
The second issue was that once this project was complete, there wasn't money for others in the Delaware Bay. And Conlon said the Corps Philadelphia District doesn't have the federal authority to do oyster shell planting projects — beyond that one-time project. In the Chesapeake, she said, there is special authority to allow the Corps to help with shell restoration projects.
"They still got some gains from it," said John Ewart, the shellfish aquaculture specialist at the University of Delaware's Sea Grant College Program. "What needs to happen those reefs need to be worked and replenished" with shell.
But the availability of shell is a huge issue and it takes tons and tons of it to make a difference, he said.
At the Maryland-based Oyster Recovery Partnership, cleaned and conditioned oysters are pre-seeded with young oysters before they are placed on reefs. And Maryland offers a tax credit to folks who recycle shell. Delaware has no such program, and seed oysters must be brought in from out-of-state and certified disease free before they can be imported and used in state waters.
Besides Casey, two non-profit groups are collecting oyster shell in Delaware: The Center for the Inland Bays and The Partnership for the Delaware Estuary.
Jeff Long, who leads the oyster shell program for the partnership, said they are collecting shell from 10 restaurants in New Castle County. In the first two months of the project, which is just getting started, they captured about 100 bushels of shell each month.
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Once the shell are cleaned and conditioned, they will be used in the partnership's Living Shoreline program, Long said.
There is no cost to restaurants that participate in shell recycling programs in Delaware but restaurants do have some extra handling. The shell has to be collected in a separate container from other waste, for instance.
Both Long and Casey said the big advantage for the restaurant is a reduction in waste hauling fees because oyster shells are heavy.
"A lot of people are interested in doing the right thing," Long said.
And Casey said many consumers are interested in knowing that the oysters they eat are sustaining the next generations of oysters.
Consumers can find restaurants that recycle oyster shell because most promote it with signs and table cards.
For Casey, it has become a mission. He promotes oyster shell recycling with the question: "R U Shellaware?"
"Most people think I take the shell and use it for road bedding," he said.
But his long term plan, he said, is to use locally to support oyster restoration in the state
"The oysters made millionaires around here" and then there was a collapse in the oyster economy, he said. "That, to me, is something we don't want to repeat."
Reach Molly Murray at (302) 463-3334 or mmurray@delawareonline.com. Follow her on Twitter @MollyMurraytnj.