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Louisiana officials monitor Bonnet Carré Spillway opening for impacts on state's oyster industry

Despite concerns about the impact of a rare spillway opening to alleviate Mississippi River flooding, Louisiana officials are cautiously optimistic about this season's oyster harvest.

The U.S. Army Corps of Engineers opened the Bonnet Carré Spillway, located about 15 miles west of New Orleans, on Jan. 10. The excess river water is being diverted into Lake Pontchartrain, the Corps said.

It was the 11th time in history that the spillway was opened during a flood threat.

Fishermen raised concerns about how the freshwater diversion may impact oyster reefs, something that occurred when the spillway was opened for more than a month in 2011, WLOX-TV reported.

Freshwater dilutes the water's salt content and can kill off oysters or stunt their growth, the Louisiana Department of Wildlife and Fisheries said in a report on the state's 2011 oyster assessment. Warmer, fresher water overrides denser salt water and limits the amount of oxygen available for the oysters' survival.

Sales figures show that Louisiana seafood industry was down slightly in 2011 with sales totaling $1.8 billion, according to the Fisheries Economics of The U.S. report by the National Oceanic and Atmospheric Administration. In 2012, the seafood industry totaled $1.9 billion.

While total estimates for this season are not yet complete, there are promising signs that this season has been more productive than the previous three seasons, Fisheries Public Information Director Rene LeBreton said.

"We are currently monitoring conditions on a day-to-day basis so that we can respond quickly if oyster resources appear in jeopardy," LeBreton said.

"We have been able to keep public oyster grounds open longer than previous years in several areas, providing additional harvest opportunities to the industry. Oyster populations are showing positive signs in the Biloxi Marsh area, Hackberry Bay and Sister Lake, where we have observed considerable settlement of larval oysters," he added.

If it becomes apparent the spillway opening will substantially impact the oyster population, the state will start a permit program in an attempt to protect oyster resources by moving them to other locations, LeBreton said.

In addition to the potential threat from the spillway release, Louisiana's oyster industry has been fighting impacts from toxic algae blooms.

"The most notable challenge [this season] has been the occurrence of a harmful algal bloom, or ‘red tide,' in the Mississippi and Chandeleur sounds, east of the Mississippi River," LeBreton said. "This event forced the Department of Health and Hospitals to close this area to oyster harvest for health concerns, which has negatively affected fishermen."

"The presence of red tide in these waters has complicated the issue for this spillway opening, preventing normal harvest but allowing oysters to be transplanted after obtaining a permit and adhering to strict permit conditions," he said. "Ironically, freshwater from the spillway is expected to help end the red tide event, as this algae cannot survive in cold, low salinity waters."