Chemical Found to Lure Nutria Out of Louisiana Wetlands

Introduced by Tabasco sauce magnate E.A. McIlhenny in the 1930s, the nutria have been especially damaging to the marshland ecology in the Mississippi Delta following Hurricanes Rita and Katrina in 2005.

McIlhenny wanted to expand the fur trade in Louisiana so he bought about two dozen nutria but eventually set them loose. The original few animals bred an estimated 20 million animals within two decades, according to a wildlife group in Maryland that tracks nutria data.

Nutria in Louisiana wetland (Photo by Mike Dunn courtesy North Carolina Museum of Natural Sciences)

As the international fur market began to shrink in the mid-1980s, the decline in fur trapping resulted in overpopulation of nutria. Annual aerial surveys from 1993 to 2001 indicated that some 100,000 acres have been impacted coastwide.

Now, Professor Athula Attygalle, an expert in molecular chemistry and mass-spectrometry based at Stevens Institute of Technology in Hoboken, New Jersey, and a team of scientists from Cornell University and University of Iowa, have found a compound the nutria like that does not damage the environment.

"Several volatile compounds, including terpenoids, fatty alcohols, fatty acids and some of their esters, were identified from solvent extracts prepared from anal scent glands of nutria," said Attygalle.

"These compounds can serve as a powerful attractant to the animals, and thus, when applied strategically, serve as a tool in the efforts to control their spread in the easily damaged coastal ecosphere," he said.

While federal agencies have looked at various poisoning methods, none of those efforts has gone very far because of their harmful effects on other species.

The Coastwide Nutria Control Program, which began in November 2002, consists of an economic incentive payment of $5 per nutria tail delivered by registered participants to collection centers established in coastal Louisiana. The goal of the program is to encourage the harvest of up to 400,000 nutria annually from coastal Louisiana.

Vegetative damage caused by nutria has been documented in at least 11 Coastal Wetlands Planning Protection and Restoration Act project sites in the Barataria-Terrebonne Basins.

When vegetation is removed from the surface of the marsh, as a result of over grazing by nutria, the fragile soils are exposed to erosion through tidal action. If damaged areas do not revegetate quickly, they will become open water as tidal scour removes soil and lowers elevation. Frequently, the plants' root systems are damaged, making recovery through vegetative regeneration slow.

The work of Professor Attygalle and his associates offers an alternative to hunting and trapping, or ecologically harmful poisoning, in the management of the nutria population.

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