Restoring Chesapeake oysters one reef at a time
Oyster reefs were once so plentiful that ships traveling across the Chesapeake Bay navigated around them.
Back in 1608, Captain John Smith wrote that the bay oysters “lay thick as stones” in the water. Well into the 19th century oysters were the basis of a booming business in bay country.
By the late 20th century and into this century, however, the oyster population was all but wiped out by overfishing, disease and pollution. In 2011, a survey estimated the oyster population had shrunk to less than 1 percent of its historic levels.
But now, oysters are making a comeback which can be traced to scientists developing a more disease resistant oyster and to a program to build sanctuary reefs in bay tributaries.
A crew from the Annapolis-based nonprofit Oyster Recovery Partnership began work Wednesday on a new reef near the mouth of the Severn River. Their lumbering 72-foot ox of a boat with oyster shells piled high on its deck made its way back and forth across a carefully plotted spot off Chinks Point for hours.
When it reached the right spot, flaps opened in barriers near the gunwales and the shells, coated with baby oysters, slid overboard into the water, in some cases urged on with the spray from a high pressure hose.
The whole operation was being driven by computers, said Tom Guay, program director of the Severn River Association, a partner with the local nonprofit in this project.
“The computer tells them which GPS coordinates to use to locate where they're actually planting the oysters,” he said. “And so the computer starts driving the boat when they're going through this planting operation.”
This will be the sixth reef in the Severn, part of the nonprofit’s “Build a Reef” program. The organization has teamed up with the Severn River Association as well as environmental groups on the Eastern Shore to restore historic oyster reefs.
“We’re opening up a new area here,” Guay said. We’re kind of running out of real estate up river. And so we're also involved in a project to identify new areas to plant these guys.”
The idea is to have “billions of these guys cleaning our river,” he said.
Scientists say replenishing the oyster population is key to restoring the Chesapeake Bay.
That’s because oysters are filter feeders, which means they can parse out pollution, such as fertilizer that has run off farm fields, to clean the water. One adult oyster can filter as much as 50 gallons of water a day. In addition, oyster reefs provide habitat for grass shrimp, mud crabs and other small critters that rockfish, blue crabs and larger creatures feed on.
The nonprofit has also rebuilt reefs on more than 1,000 acres on the bottoms of Harris Creek, the Little Choptank River and the Tred Avon, all Choptank tributaries, as well as in Eastern Bay.
Ward Slacum, ORP’s executive director, says the “Build a Reef” program, now in its fourth year, is part of a statewide effort to restore the Chesapeake’s oyster population.
State officials have “committed to restoring oyster populations in five tributaries by 2025,” he said, “repopulating public oyster grounds,” and helping a fledgling, but fast-growing aquaculture industry.
Working with the state, he said, ORP “has planted more than 9 billion oysters in the Chesapeake Bay since 1993.”
The shells come from ORP’s shell recycling program. Crews pick up oyster shells from restaurants, bars and even landfills from around Maryland and haul them to a landfill in Grasonville, just the other side of the Kent Narrows, clean them and take them to the University of Maryland’s Horn Point Hatchery near Cambridge.
Scientists there place the shells in a tank and release free-swimming oyster larvae into the water, said Jesse Iliff, executive director of the Severn River Association.
The larvae, which look like wet, gray sand, scatter about in the water until they touch something hard, he says, like an oyster shell. “And oysters like old oysters more than anything else to grow on.”
Iliff says the shells in this operation have between five and 30 baby oysters clinging to them, each one no bigger than a tiny dot.
“And in a year, those dots will turn into something the size of a penny or a nickel,” he adds. “In two years, they'll be about the size of a silver dollar and in three years, they would be big enough to harvest.”
But these oysters won’t be harvested and they won’t show up on the half shell at your favorite seafood restaurant, he adds. They’re protected because of their ecological value.