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Recycling Oyster Shells Keep the Seafood Supply Coming

The ocean off South Carolina’s shores teems with life, as do its estuaries.  According to Ben Dyar, head of shellfish management for the South Carolina Department of Natural Resources, a major contributor to this abundance is an undersea "wall" that provides the state a wealth of seafood and wildlife habitat: oyster reefs.  Dyar says a main ingredient to a healthy oyster crop is old oyster shells, and the state needs more of them.

"To be able to properly manage our oyster populations, we have to put oysters back in the water," he said.  "When we do that, those oysters will recruit baby oysters and create new habitat.  To do that, we have to have the oyster shell.  And the problem is, we’re just not getting enough."

DNR oyster shell public drop off at The Sands Port Royal Boat Landing in Beaufort County, South Carolina.
Credit SC DNR
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DNR oyster shell public drop off at The Sands Port Royal Boat Landing in Beaufort County, South Carolina.

Recycling empty oyster shells is important enough for the Department to have a program devoted to that pursuit.  Dyar's colleague Michael Hodges is manager of the South Carolina Oyster Recycling and Enhancement program, or SCORE.  He said that DNR averages replacing 27,000 bushels of shells per year.  2020 was on track for a record 38,000 bushels until COVID interrupted.

"When it became apparent that COVID was gonna be a real issue, we saw the oyster roasts stop, we saw the restaurants being closed, we saw the weekend events, the fundraisers, those just came to a halt. And during oyster season in South Carolina, that’s when we’re recycling most of our shells.  And when our sources of shells stops, that means we’re unable to recycle as many oysters."

Hodges laments every bushel lost to the pandemic.  He said a large public event such as the annual oyster roast at Boone Hall Plantation can generate as much as 1000 bushels of used shells. 

"A thousand bushels can go a long way," said Hodges.  "That will cover about one-tenth of an acre of resource.  And once you factor in all the other community events where they’re serving 100 bushels, 150 bushels or even 50 bushels, those add up over time."

Dyer said oysters are very beneficial to the ecology of the state, as well as the seafood economy.

"They are filter feeders, so whenever they’re feeding, they’re filtering water.   This helps filter out particulates and sediments out of the water.  An adult oyster can filter up to 50 gallons a day."  In addition, said Dyar, "they provide barriers to our marshes to help curb erosion.  And they also provide a habitat to nearly 140 different species of invertebrates and small organisms that then bring in the larger predator organisms that a lot of people like to fish for, such as the red drum and the flouder and the trout."

Image of a mud bank in Sewee Bay in Charleston County before planting and (right) the same mud bank with live, healthy oyster reef habitat one year after planting with recycled shells.
Credit SC DNR
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Image of a mud bank in Sewee Bay in Charleston County before planting and (right) the same mud bank with live, healthy oyster reef habitat one year after planting with recycled shells.

Used oyster shells are “planted” each summer using scientific criteria to determine the best location.  Dyar said the locations are marked with poles when the tide is low.

"So at high tide, we’ll load a barge with the oyster shells, usually about a thousand bushels at a time.  And then using a high pressure water pump, the pump will push the shell over the side in the desired location.  So the oysters will spawn, there will be a free-swimming, microscopic larvae.  If they land on a soft substrate, they may not survive.  But if they land on some hard substrate, they can attach themselves, create their own shell and start to filter and feed and survive.  So that's why you might see them on rock pilings and bridges and things like that.  But their most preferred habitat or hard substrate is other oyster shells."

DNR gets used shells from restaurants, but also depends on the public to bring old shells to a number of shell recycling bins throughout the state, said Dyar. "Our largest source of shell is from the public drop off location.  We can’t do this without the public’s help.  We have to have the public support to bring us the shell to these public dropoff locations."

"The only thing we ask for the folks who are gonna be recycling is to try to remove as much trash as you can from the shells themselves," added Hodges.   "But every bushel counts, even if it’s one five-gallon bucket or just a handful of oyster shells.  We can cover 10 square feet with three bushels of oysters, and it’s not unheard of for us to have many thousands of oysters to grow in 10 square feet.  And so just a little bit of shell goes a long way."

Both men said that every shell that goes back into South Carolina waters will benefit the state in the long run in the form of protected shorelines, cleaner water and plentiful seafood.

DNR has public oyster recycling bins all up and down the coast, and as far inland as Greenville, plus several locations in the Midlands, such as Columbia and Camden.  A full list of locations can be found at saltwaterfishing.sc.gov.  Click Oyster Recycling for the list, maps and a list of "dos and don'ts."