Death on the half-shell: Flood could kill 90 percent of state’s oysters

June 19, 2011

Economic Development

Another major disaster is facing Mississippi, and this one could totally wipe out Mississippi’s oysters. If that happens it could be months — perhaps years — before another oyster is harvested in Mississippi waters.

The historic Mississippi River flood has dumped so much freshwater into the Mississippi Sound that scientists are concerned that there will be no harvest season this year. Dave Burrage, Mississippi State University Extension Service professor of marine resources, is expecting catastrophic losses.

“Oysters are stationary and cannot escape as the freshwater displaces the saltwater they need,” Burrage said in a statement.

Oysters prefer brackish waters with a mix of saltwater and freshwater. When that mixture becomes imbalanced as is the case now, oysters cannot thrive.

Burrage told the MBJ the infusion of some freshwater could actually help oysters by beating back their saltwater-loving predators. But the historic river flood has salinity levels so low that losses could be total.

“Oysters just cannot survive long periods of freshwater, so we are expecting significant mortality, maybe even 100 percent,” he said.

The threat from the floodwaters is yet another challenge for the state’s oystermen still reeling from Hurricane Katrina in 2005 and the BP oil spill last year.

The numbers are sobering. The MSU Extension Service’s Coastal Research & Extension Center pegged the total output of the state’s oyster industry at $71.92 million in 2000. Total indirect business taxes were $4.31 million.

In 2007, the Center estimated the industry’s total economic output at a mere $12.17 million, and the indirect business taxes generated totaled only $200,000.

Before Katrina, oystermen were harvesting roughly 300,000 sacks of oysters per harvest season, which runs from October through April. Last year saw only 43,702 sacks landed.

“A lot of people don’t realize it, but there was a year or two before Katrina when oysters harvested in Mississippi exceeded those landed on the entire East Coast,” said Scott Gordon, director of the Shellfish Bureau.

Gordon’s initial mortality estimate agreed with Burrage’s 100 percent loss. However, he is now forecasting some oysters, perhaps only 5 percent, will survive. This is primarily due to the drought conditions currently being experienced on the Coast.

The dry conditions have lowered the Pearl, Wolf and Jordan rivers, all of which feed into the Sound. The drought has decreased the amount of freshwater flow from these rivers, keeping freshwater levels lower than anticipated.

Still, the losses are already mounting. At press time, teams sampling the state’s oyster reefs were reporting mortality from reef to reef ranging from 6 percent to 95 percent.

But those numbers are rising. Gordon said one of the reefs that was sampled early showed a mortality rate of 6 percent. On June 14, that reef’s mortality rate had reached 68 percent.

“(On June 14) we found dead and dying oysters all over the western reefs,” he said.

Gordon added that he is now concerned about lowering oxygen levels as waters warm. Warm waters are being pointed to as the possible reason behind a high oyster mortality rate in 2010, though researchers are still unsure how much, if any, the BP oil spill played in those oyster deaths.

Hurricanes this year are another concern. Burrage said the final loss tally from Katrina was roughly 90 percent.

In March 2010, more than four years after the storm, the Mississippi Department of Marine Resources reported that Mississippi’s oyster reefs had finally been restored to pre- Katrina conditions.

This effort was led by the planting of cultch, introduced material made from gravel or shells that forms the basis of an oyster bed. Since Katrina some $13 million has been spent on cultch planting. Another $3-million planting is slated for August and September – barring a hurricane or other adverse factors. In fact, the August-September cultch planting is a carry over from an earlier planned planting that was postponed due to the flooding Mississippi River.

Gordon said a hurricane this year could mean a dormant industry for years to come.

As it is now, the oyster industry is already facing a long comeback. It takes anywhere from 18-24 months for oysters to grow out to legal, harvestable size. If the oyster population is wiped out this year, it could be 2013 before the next harvest season.

With all of the challenges faced over the last decade, many oystermen have opted out, Burrage said. Some have chosen to expand and/or cross over into shrimping or crabbing while others have found work landside.

Gordon has been working in the industry since 1982, and has been the Shellfish Bureau director since 1997. He said that the current state of the industry is the worst since he has been involved in the industry.

Gordon said sarcastically that he was going to write a book titled “Oyster Disasters I Have Seen.” But he said he does not expect this disaster to be the industry’s death knell.

“These (oystermen) are pretty tough and resilient,” he said. “They love what they do – wouldn’t do anything else.”

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