COASTAL CONSEQUENCES
Calculating how restoration could affect life around Louisiana’s coast

During the early 19th century, the famous Louisiana pirate Jean Lafitte and his band of smugglers wrought havoc on Spanish merchant ships from Barataria Bay, which is south of New Orleans, to Galveston, Texas. Barataria became their home, and the fish species that lived in those waters quite possibly became a staple of their diet.

Today, much like Lafitte and his men, sportsmen and commercial fishermen enjoy the abundant offerings of Barataria's waters. However, the fish populations of Barataria and similar environments could be in danger if research is not done to examine the impact of coastal restoration projects on fish and the fisheries industry, says Jim Cowan, a professor in the LSU Department of Oceanography and Coastal Sciences and the Coastal Fisheries Institute.

"If we are to restore Louisiana's coastal environment, then it is critical that we understand how it will affect fisheries. We must do this to keep our Sportsman's Paradise from waning," says Cowan, who has spent the past 20 years conducting fisheries research in marine and estuarine ecosystems.

Cowan and his research team are striving to predict how some coastal restoration efforts, such as the creation of large-scale water diversions and delta systems, will affect fish populations. With more than $1 million in grant support from the Louisiana Department of Wildlife and Fisheries over the next three years, they are learning more about what the day in the life of a fish is like and how different habitats contribute to the health of fish stocks in Barataria Bay.

Bordered by the Mississippi River to the east, Bayou Lafourche to the west, Lake Des Almonds to the north, and Grand Isle to the south, Barataria Bay is one of the most productive estuaries in Louisiana. It is home to several commercially fished species, including shrimp, blue crabs, and oysters, on which many of the local economies are extremely dependent.

Studying the life and environment of fish species is no easy task. To gather the data he needs, Cowan is leading a variety of projects in the area. Using a LDWF Marine Lab on the barrier island of Grande Terre and technology such as side-scan sonar and other hydroacoustic sampling devices, Cowan and his team are beginning to paint a better picture of the environment and its effect on biomass under Barataria's surface.

As it is towed through the water, the side-scan sonar device sends pulses of sound to the sea floor, which are reflected back to the device, giving a picture of the habitats below. It is so precise at finding and determining the density of oyster reef beds that it can even "see" where boat anchors have been placed or dragged.

Comparing total biomass, species composition, and predator-prey relationships from various environments within Barataria, such as soft-bottom and hard-bottom, or marsh edge and flooded marsh habitat, will allow them to determine how different fish species utilize these environments and how sensitive they may be to any ecological changes caused by coastal restoration efforts. Such studies will hopefully help to sustain life in the ecosystem and the livelihood of local commercial fishermen.

Cowan says, "Everything we do is meant to be valuable to the management community—to help them make the best decisions they can when it comes to resource protection and coastal restoration."

ON THE WEB:
LSU Department of Oceanography & Coastal Sciences
LSU Coastal Fisheries Institute

from Spring 2005