In Louisiana’s Lake Calcasieu, barges are busy ferrying loads of limestone to the southeastern end of the lake, hauled from quarries in Missouri and Kentucky. Floated to spots near the lake’s edge with good water flow and depth, the limestone is dumped—by careful design—into 100-foot-long rows that parallel the shore.
After about 18 of these barges are emptied, 18 new acres of new oyster reef will be ready for their residents to move in and settle down. It’s part of a suite of restoration work to address impacts from a 2006 oil spill to the north.
Oysters thrive in the warm, nutrient-rich waters of Lake Calcasieu. November and December are prime months for oyster recruitment in southwestern Louisiana, following fall spawns, said Brady Carter. He’s a Coastal Resources Scientist Manager with project partner Louisiana Department of Wildlife and Fisheries, which is leading the implementation of the project. Given proper conditions, Carter added, spat should be settling out on the rocks almost immediately. Six months after construction, the reefs could have healthy populations of “seed oysters,” which are between 1 and 3 inches long.
“This is adding more substrate to increase the area of grounds that produce oysters,” Carter said. “While we have more than 1 million acres of public seed ground, only a small portion of that has oysters that we know about, or manage. This expands the area with resources that the state is aware of.”
From an ecosystem perspective, the oyster reef brings many benefits to the lake: adult oysters are powerful filter feeders. A single individual can filter 20 to 50 gallons of water per day. Oyster reefs also offer lots of nooks and crannies for invertebrates and small fish to hide in. These, in turn, provide ample hunting and feeding opportunities for larger species of fish—and nursery grounds for their young.
“Bottom-dwelling invertebrates prefer this kind of habitat,” said John Barco, the Gulf of Mexico team lead for the NOAA Restoration Center’s Southeast Region. “Having that water quality is vital, and there’s a food web component that this reef provides for numerous other species.”
From a human perspective, the new reef also offers economic benefits: additional oyster harvesting grounds. Once subjected to overharvesting via mechanical dredging, harvests on the lake are now limited to tonging. This technique is less damaging to the reefs and makes for less intensive harvests. Daily bag limits are currently at 15 sacks per commercial vessel and two sacks for individuals with a recreational fishing license. A sack weighs about 100 pounds, or about 180 oysters depending on their size.
Calcasieu Lake’s oyster season is rarely ever closed early due to its harvest threshold being met, Carter added.
Once complete and mature, the project’s reef would be open to commercial and recreational harvesting. From Calcasieu, oysters travel locally and more widely. They’re served in restaurants, shucked and canned in local processing plants, and shipped out of state for sale as whole oysters.
“We love eating oysters down here,” Carter said.
Oil Spill History
The Lake Calcasieu oyster reef project is one of three from a 2022 restoration plan approved to compensate for impacts from the 2006 Citgo Refinery oil spill. The spill harmed more than 150 miles of coastal marshes and waterways in southwestern Louisiana. The release of oil and wastewater polluted intertidal and subtidal sediments, and killed many fish and bottom-dwelling organisms like oysters. A 2021 settlement provided $19 million toward restoration, including the oyster project.