Reduced Freshwater Inflow to Florida Panhandle to Blame for Oyster Die-off
Low catch adds to woes of oyestermen struggling to stay afloat in a tough economy
When oystermen in Apalachicola Bay pulled up bags from their winter harvest grounds last year, 95 percent of the oysters were already dead. The discovery sent shockwaves through the oyster-fishing community in Franklin County, FL.
Photo by Nolan Williamson
Apalachicola Bay, an area of about 208 square miles on Florida's northwest coast, is one of the most productive estuarine systems in the Northern hemisphere. The bay is home to an incredible variety of plants, animals, birds, and marine life. But most of all, it’s renowned for its oysters.
The mollusks are the key source of income for the county of 11,000, where an estimated 2,700 to 4,000 people work in the oyster-fishing business for at least some part of the year. The 1037-square-mile county sits in Florida’s “armpit” about 80 miles southwest of Florida’s capital, Tallahassee. Only 50 percent of Franklin County’s 1037 square miles is land, and of that land nearly 80 percent is state or national forest (Tate’s Hell State Forest takes up about 300 square miles and part of Apalachicola National Forest occupies 34 square miles). The other part of Franklin County is water.
“In Apalachicola you either work for the government or the prisons or you work in oysters,” said Brian Mayer, assistant professor of sociology at the University of Florida in Gainesville. Mayer has been studying resiliency in Gulf coast communities since the BP oil disaster. The oyster die-off has added to the woes of residents already struggling to stay afloat in a fragile economy.
“It was a tough summer and “not as nearly as productive as in the past,” he reported. “This die-off has just added to the frustration of the oystermen in the Apalachicola area.” With the winter harvest failure, a lot of people are out of work and will be so for some time because it takes two years for an oyster to mature enough to harvest.
In 2011, 2.6 million pounds of oysters were harvested in Florida at a value of about $7.4 million. Franklin County accounted for 2.3 million pounds of that total. In early January, the Florida Fish and Wildlife Conservation Commission reported that the harvest was down by about 80 percent from previous years.
In early October, Florida Governor Rick Scott requested federal disaster relief funds for families and businesses, which finally materialized in early December in the form of a $2.7 million National Emergency Grant from the US Department of Labor. The funds will provide jobs seafood workers that lost their livelihoods because of the die-off or due to oyster reef damage caused by Tropical Storm Debby in June 2012.
Meanwhile, scientists with University of Florida’s Oyster Recovery Team are analyzing data and assembling information that will lead to more adaptive and resilient efforts to protect and manage Apalachicola’s historic seafood industry. The team — led by Karl Havens, director of Florida Sea Grant, a program that supports research and education activities that help the state’s shoreline communities and industries — has formed six separate divisions to examine the possible causes of the die-off: contaminants and pathogens, water flow and salinity, nutrient inputs, oyster population dynamics, fisheries modeling, and food safety.
Initially, Mayer said, the community blamed the die-off on the 2010 BP oil blowout in the Gulf of Mexico; however, experts claim at this time that oil is not the culprit. Although the research is not complete, the general opinion among scientists, researchers, and state agencies is that a predominant cause of the die-off is lack of freshwater in oyster reef areas. Oysters require a delicate balance of just the right salinity — too little or too much can result in a decline in their numbers.
In Apalachicola Bay, freshwater inflow to the region’s estuarine habitats where oysters and other marine life thrive has been on the decline due to overconsumption of ground water, drought, and land use changes, which have led to increasingly saline water in the bay, experts say. Higher temperatures, disease, and lower dissolved oxygen may have played roles as well. The recent severe drought in the Southeast has caused a decline in freshwater flow from the Apalachicola River, according to Peter Frederick, research professor in the Department of Wildlife Ecology and Conservation at the University of Florida.
In addition, he said, oyster harvesting off the Florida coast is different from colder northern waters, Frederick explained. “In Chesapeake Bay an eight-year old oyster is considered old. In Cedar Key and to some extent in Apalachicola as well, a two-year old oyster is an old oyster.”
Oysters in the Gulf succumb very quickly to predation, disease, and all sorts of mortality. To maintain a population, there must be annual “recruitment” to reef. This takes place after a complicated process of spawning — once the eggs are fertilized, the larvae, called “spat,” attach themselves to a nearby substrate, usually nearby older oyster shells.
To ensure that there’s a constant supply of emerging oysters on the reefs, only oysters larger than three inches may be legally harvested. But if smaller oysters are taken in excess and “you have a series of three to five years where you do not get any recruitment, pretty much all the oysters on the reef will die,” Frederick explained.
While periodic droughts and the resulting higher salinity are normal, long-term (or multiyear) severe droughts coupled with decreased freshwater flow and “decimation of the bar due to disease and predation” can break up the reef because it is less cohesive and vulnerable to wave action. “Once this happens it’s a difficult box to get out of,” said Frederick. More erosion means further degradation of the reef into sand, and oysters cannot attach to sand.
While the drought has definitely contributed to the lack of freshwater in the bay, land use and overconsumption of freshwater are chronic and growing problems. And these problems start upstream in Atlanta, Georgia. As the population of Atlanta grows and the urban area expands, less freshwater makes it into the Apalachicola Bay. In fact, Florida, Georgia, and Alabama have been battling over water rights for over two decades now. Florida claims huge consumption demand upstream, diverts the natural flow of water through the Apalachicola-Chattahoochee-Flint (ACF) Basin to Apalachicola Bay in the Florida Panhandle. (Read an in-depth account of the tri-state water battles and its impact on Florida oysters here.)
Not all Florida Panhandle oysters have suffered such a huge die-off. Areas in Bay County to the west of Apalachicola were thriving in early fall. The fact that Franklin is the only Florida county with back-to-back open seasons may also have contributed to the stress on oyster communities. Current bag limits for oyster harvesting in Apalachicola are 20 bags per day per person (or vessel). A bag equals about two, five-gallon buckets — or about 60 pounds.
In November, the Florida Department of Agriculture and Consumer Services initiated a weekend ban on commercial oyster harvesting to relieve some of the pressure on the oyster populations. The ban is automatic when the agency determines that monitored oyster bars cannot sustain a harvest of 300 bags of oysters per acre.
In the meantime, Mayer said, he and other researchers from universities in Florida, Maryland, Louisiana, and Alabama continue to offer support to Gulf Coast communities through Healthy Gulf, Healthy Communities, a coalition of biologists, psychologists, social scientists, and community members formed after the 2010 Deepwater Horizon disaster that takes an interdisciplinary approach the environmental, economic, and emotional health.
“In these kinds of situations you have to do more than research,” Mayer said, noting that the economic and emotional fallout from the oyster die-off took precedence over the research focus of the coalition. “You have to just jump in and help.”