Oyster Reefs Can’t be Rebuilt Fast Enough

Swamp Stomp

Volume 17, Issue 16

The Chesapeake Bay has a serious problem.  The oyster population and the reefs in the Bay are diminishing and cannot be replaced fast enough.  The big issue regarding the oyster population is with the shells.

The oyster population cannot be restored because there are not enough shells to rebuild the Chesapeake Bay’s depleted bivalve population.  The Virginia area has been hit the hardest.  In this area, there may not even be enough shells to sustain the wild fishery for a whole lot longer.

The situation got this way due to decades of overharvesting, habitat destruction, disease and poor water quality.  The population of oysters in the Bay has reduced to less than 1 percent of its historic levels.  The fact that there are not enough shells also affects the oyster reefs not just the oyster themselves.  Oyster reefs are made up of the shells of living and dead bivalves and they are wearing down and disappearing faster than they are being built up.

Scientists, managers and others are concerned that there are not enough shells to go around sustaining both the traditional wild fishery as well as grow the aquaculture industry.  This does not take into consideration the ambitious large-scale efforts by both states and the federal government to restore the Chesapeake’s oyster population for its ecological value.

“We don’t have the habitat,” said Bruce Vogt, manager of ecosystem science and habitat assessment for the National Oceanic and Atmospheric Administration Chesapeake Bay Office. “Even if we had adequate spawning stock to revive the population over time, the habitat just isn’t there.”

The problem with not having enough shells is twofold.  “Oysters make their own habitat, building reefs out of the shells they produce. But juvenile oysters need a hard surface — customarily, another oyster shell — on which to grow. The problem now is that there are many fewer shells than there used to be on which the shellfish can live and reproduce” (Wheeler).

There used to be 450,000 acres of oyster reef habitat that once blanketed the bottom of the Bay and its tributaries.  Of the 450,000 acres, 70 percent has been lost to siltation, according to an environmental assessment done in 2009 by the U.S. Army Corps of Engineers.  The silt that is covering and destroying the reefs has yet to let up.

The shells are also being destroyed by predators.  Shells are also removed by harvesting and are not always returned.  In addition, the gear used to dredge up oysters scatters and breaks other shells.

The biggest challenge to restoring the oyster population and reefs is that there shells break down naturally overtime.  If there is a live oyster in the shell, they produce new shell from carbon and calcium and they filter out water.  After the bivalves die, corrosion sets in.  The process is hastened if the water is saltier or more acidic.

In order to get to the bottom of how to fix the problem, the state-federal Chesapeake Bay Program is commissioning a “shell budget” — an analysis of how many oyster shells are being lost and how many produced by new oysters.  The study is expected to take a year and the cost is estimated at $50,000–$60,000.

“We really need to put all this together,” said Peyton Robertson, director of NOAA’s Bay office and co-chair of the Bay Program’s Sustainable Fisheries Goal Implementation Team. “We don’t have a good handle on the puts and takes of shell coming in and going out.”

Source: Wheeler, Timothy B. “Chesapeake Losing Its Oyster Reefs Faster than They Can Be Rebuilt.” Bay Journal RSS. Bay Journal RSS, 29 Jan. 2017. Web. 13 Mar. 2017.

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