How Did the Nutria Get Loose in Louisiana?

By Betty Lewis

Now seen in 18 states in the US, nutria originally made their North American debut in Louisiana in the 1930s. They thrive in wetlands, dining on a wide variety of plants, including agricultural crops. They're wasteful, voracious eaters, impacting about 34,000 acres of wetland.

Meet the Nutria

Nutria are unremarkable web-footed creatures, weighing between 15 and 22 pounds. They have forelegs built for digging, so they're very effective at excavating the marsh roots of their home. Their long buck-teeth allow them to eat three pounds of marsh plants in a day. The nutria's native range is South America, including Chile, Brazil, Argentina, Bolivia, Uruguay and Paraguay. Unfortunately, since being introduced to Louisiana in the 1930's, they've contributed to the devastation of the state's wetlands.

Good Intentions Gone Awry

Nutria were introduced to Louisiana in the 1930's for commercial fur farming. After a group of 20 were purchased from a fur dealer, they were released into the marshes. Up through the 1940's nutria were promoted as a natural and effective solution to aquatic weeds, such as water hyacinth, so some were transplanted throughout southeastern Louisiana. Also, nutria breed year round, averaging four or five nutria per litter. One female can produce an average of a dozen offspring annually; though litter sizes can go up to 13 nutria.

Too Many Nutria

It only takes days for a young nutria to begin munching on the marsh vegetation around him. The result is devastating for their habitat, wetlands and some agriculture. This was apparent in the 1950s, when farmers reported damage to rice and sugarcane fields. By 1958, when they numbered approximately 20 million in number, nutria weren't considered so helpful for controlling pesky plants and were removed from the state's list of protected wildlife. Trappers went to work to use nutria pelts to meet demand in the fur industry, bringing the population to a more reasonable level. From 1965 to 1982 trapping and severe weather incidents kept the population lower and nutria were back on the protected wildlife list.

I'll Be Back

Prolific breeding, a decline in the demand for nutria pelts and erosion of wetlands from weather have all combined to again make nutria more pest than helper. Nutria have fed their negative reputation as the more they eat, the more they contribute to wetland erosion. They feed on grassy marsh, converting it to open water, ultimately leading to erosion. Government agencies have worked to get the nutria population under control through hunting, trapping and poisoning, however to date, the rodents still rule the marshland roost in Louisiana.