Restoration to Aid Oyster Fisheries Fight for Surivival

Multi-institution study sets out to guide restoration of the world's most devastated estuarine habitats

04-11-2011 // Bob Serata

A recent study published in the journal Bioscience documents the almost total devastation of the worldwide oyster fishery, substantiating what every oysterman and resource manager in the U.S. has known for 100 years – there aren’t too many oysters left, and the oyster fisheries that do survive in the Gulf of Mexico and southeast Atlantic coast have just about had it.

By the mid-1980s, scientific journals were reporting that oyster harvests were 1-2 percent of historic peaks in areas of Chesapeake Bay and along the North Carolina coast, America’s premier oyster fisheries. Noted scientist Jeremy Jackson, of Scripps Institution of Oceanography, wrote in 2001 that the Chesapeake Bay oyster fishery was overfished to the point of “ecological extinction.”

oysters

Apalachicola Bay, St. George Sound, St. Vincent Sound and East Bay make up a 208-square-mile oyster fishery that produces an estimated 90 percent of Florida’s oysters. Overfishing aside, the bay’s oyster population fights to survive occasional industrial spills flowing down the Apalachicola and Chattahoochee Rivers, red tides, bacterial and viral outbreaks and, of course, hurricanes — Elena in 1985 and Dennis in 2005, to name two that wiped out oyster reefs and beds.

Mississippi oysters fight the same battles, for instance, the recent closure of oyster beds due to runoff from the Pearl River.

Louisiana’s oyster beds have not yet suffered the same fate of most of those along the Gulf coasts. They remain vast and productive, but the oil spill demonstrated their vulnerability to real threats. And the ongoing disappearance of Louisiana's estuarine marshes threatens to erode their future sustainability.

Turn Back the Tide

In the face of the Gulf disaster, Louisiana officials tried to keep the oil out of estuaries during the spill by releasing massive amounts of fresh water from the Mississippi River, with the hope that higher water levels would push against the incoming tide of crude. Though crude did enter the estuaries, it could have been much worse. Whether the river water helped stave off disaster is unclear, but months of freshwater killed many thousands of acres of farmed reef in the Barataria and Breton basins. As salinity returns to its usual levels, these reefs will likely recover.

The researchers who studied the global oyster population call for “conservation, restoration, and management of fisheries,” all of which are good ideas; none of which are new ideas. They also offer a “reasonable” proposition: “Where oyster populations constitute less than 10 percent of their prior abundances, we recommend no further reef destruction and the prohibition of harvests, unless it can be shown that they do not substantially affect reef recovery.” They’re probably correct. But then again, they’ve got jobs outside the oyster industry.

Instead of shutting down oyster fisheries (and immediately throwing 20-30,000 people out of work), restoration offers a potential road to recovery.

There have been lots of restoration efforts over the years. Governments, universities and environmental groups have worked to restore oyster reefs. National Wildlife Federation and state affiliate Alabama Wildlife Federation contributed $50,000 and $10,000, respectively to get the launch phase of the 100-1000 Project completed. The money will help 100-1000 restore previously destroyed habitat for oysters to settle, grow and build new reefs.

Here’s hoping the project works. Many do. But many don’t. It would be nice to know why.

That’s what Dr. David Kimbro, of Florida State University’s Coastal and Marine Laboratory, hopes to find out. He is leading four teams of scientists from Florida, Georgia, North Carolina and Maine in a massive effort to study the health and future of the nation’s natural oyster reefs in 12 estuaries spanning 1,000 miles of Atlantic and Gulf of Mexico shoreline.

More than Just Food

Oysters are ecosystem engineers. They filter water, build reef habitats that support dozens of other species, and stabilize shorelines, activities called “ecoservices.” But most research to date focuses on the fishery aspect of oysters — how many and where are they? Instead, Kimbro’s teams will be looking at the ecoservices oysters provide.

“Right now, we are examining how the services provided by oysters might change from North Carolina to Florida and why these differences might arise,” said Kimbro. “Hopefully, we’ll learn why some services are working better on some natural oyster reefs but not in other natural reefs,” he added.

Kimbro continued, “One of the things that may influence the ability of oyster reefs to sustain themselves, or to be restored, is the local predator community. Predators differ from location to location so their effects on oyster restoration will differ,” he said.

Heading the teams are FSU Coastal and Marine Laboratory marine ecologist Anne Randall Hughes and scientists James Byers, of the University of Georgia; Michael Piehler, University of North Carolina-Chapel Hill; and Jonathan Grabowski, of the Gulf of Maine Research Institute.

The reasons for collapsed oyster fisheries are familiar — overfishing, environmental degradation, invasive species, climate changes, oil — but the explanations for successful restoration are not so clear.

“We want to get a snapshot of the food web pyramid and the environments to see how the conditions of oyster reefs differ in different environments, with different predators,” Kimbro said. “Then we want to define experimentally how predators are linked to reef sustainability and water filtration services. Resource managers could then take a more adaptive management approach for sustaining and restoring oyster reefs,” he added.

“If they’re going to do a restoration project they’ll have a monitoring program and the baseline data in place to keep tabs on it, so if something doesn’t work out they can note it and note why, and change direction to do something that’s more productive,” said Kimbro.

 

 

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