While researching the demise of Louisiana’s coastal wetlands, I was intrigued by the fact that nutria kept cropping up as one of the natural causes of wetland decimation along with wave erosion, rising sea levels, storms and others. Not because nutria aren’t notorious for the damage they can do to marsh ecosystems, but because today they are thought of as “natural.” I guess 75 years from now we will think of hemlock wooly adelgids as a great natural disaster.

Nutria are introduced exotic invasives. They are native to Argentina, Uruguay, Chile, Brazil, Bolivia and Paraguay where they are known as “coypu.” Jim Dillard wrote in the Cross Timbers (Texas) newsletter that nutria were first introduced in Elizabeth Lake, Calif., in 1899 for fur farming. They were imported to fur farms in coastal Louisiana in the late 1920s and 1930s. P.T. Barnum would have been proud of whoever was in charge of marketing this marsh rat to U.S. fur breeders. They were marketed as the next “mink” and breeding pairs sold for as much as $2,500.

One of South Louisiana’s great entrepreneurs, E.A. McIlhenny of Tabasco fame was reported to have imported about 20 ragondins — the Cajun name — to his Avery Island farm in 1938. These critters somehow found their way into the marsh like so many others from fur farms along the Gulf Coast. It is believed that trappers aided and abetted the spread of nutria in the wild. By the mid 1940s, nutria began to appear in the Louisiana fur market.

Nutria are prolific rodents. Males reach sexual maturity between four and nine months – females between three and nine months. They breed year round and the average litter is five. By the end of the 1950’s, there were more than 15 million nutria in coastal Louisiana. People began to take note of the damage these marsh rats were wreaking on coastal wetlands, rice and sugarcane farms, and levee systems.

I guess all that breeding makes them hungry because they will consume about a quarter of their body weight daily. They feed on the stems and roots and rhizomes of aquatic vegetation and can completely denude an area of marsh before moving on.

In 1957 Hurricane Audrey came ashore a few miles east of where Rita recently made landfall. Audrey packed a huge storm surge which carried nutria farther inland, speeding the rate of dispersal.

Love / hate relationship

For whatever reason — perhaps it was that “new mink” image — until Audrey, nutria had been one of Louisiana Wildlife and Fisheries’ little darlings. But when Audrey pushed them into the rice and cane fields, Louisiana farmers had a decidedly different opinion. In 1958 nutria were taken off the protected wildlife list.

Perhaps this is where “natural” began to be assimilated into the lexicon regarding nutria. LWF was touting the nutria as a natural resource, and by 1965 it was back on the protected wildlife list. From the 1960s to the 1980s, about 1.3 million nutria were harvested annually in Louisiana creating an $8 million industry. Because of trapping, habitat degradation, and an increase in alligators, nutria numbers began to decline in the mid-1970s.

Everyone — except maybe the nutria — seemed happy. Trappers were getting good prices — around $8 per pelt — and nutria numbers were low, so there was little crop and/or wetland damage and even the alligators looked fatter and happier.

But the honeymoon ended. The fur market took a jolt in the mid-1980s and nutria pelts tumbled to $4 each. The little mink turned out to be a little impostor, pelt-prices tumbled even more, and trappers quit paying attention.

Now the nutria were happy. Populations quickly rebounded but fur prices didn’t. With increased nutria populations comes increased wetlands damage. So today the state of Louisiana is subsidizing nutria trappers to the tune of $4 a pelt. What a natural resource, huh?

I wonder what we could get for an adelgid pelt?

(Don Hendershot can be reached at ddihen@earthlink.net.)