PHOTO: Brian Henderson/Flickr
Karen Lanier
July 25, 2018

Nutria. Never heard of them? Louisiana marsh dwellers know them all too well. A large rodent, more closely related to guinea pigs and chinchillas than to rats, nutria are about the size of a small dog at 14 to 22 pounds. Not to be confused with the Spanish word nutria for “otter,” these mammals are also known as coypu, from their scientific name Myocastor coypus.

Like muskrats, nutria are semi-aquatic and gnaw on shoots of tender plants and tree bark. The most succulent basal stems, roots, tubers and rhizomes are the animal’s favorite foods. The occasional crustacean or mussel gets swept into the mix of the nutria’s mostly vegetarian diet. With webbed hind feet, goggle-like membranes that protect the eyes, and watertight seals across their nostrils and ears, nutria are similar to beaver, but without the big, flat tail. They can swim for as long as five minutes under water. These animals are prolific breeders, and they can even nurse their young while swimming. They sometimes use the lodges of muskrat and beaver as their feeding platforms. They also live in burrows not far from the water.

Unlike muskrat and beaver, nutria are not native to North America. Originating in the tropical forests of South America, the nutria’s preferred habitat is fresh water or brackish marshes. They have been introduced throughout the world. The history of the animal colonizing and overrunning coastal wetlands in North America reflects the fluctuating value of fur markets. Nutria were brought to California and the southern coastal states as farmed fur-bearing animals (and also used as weed control in Arkansas and Alabama), but when the price of pelts decreased drastically during the Great Depression, farmers released their animals to the wild.

Particularly in Louisiana, nutria have flourished in habitats much like their warm, humid homeland, despite many attempts to eradicate them. Shortly after their release in the 1930s, they were quickly trapped and controlled. Ironically, the holding pens were damaged by a hurricane and the nutria escaped again in 1938. Fast-forward 80 years, and the animals have exacerbated the damage done by hurricanes. Nutria overgrazing on wetlands has affected an estimated minimum of 100,000 acres along the Louisiana coast, where the fragile soils get exposed and erode, after which root systems are damaged and don’t recover quickly. According to a National Geographic interview with an official at the Louisiana Department of Wildlife and Fisheries, wetland soil erosion results in about a foot higher storm surge for every mile of wetland lost.

Nutria populations over the past century have waxed and waned, affecting the growth of sugarcane, rice and wetlands in 17 states. The tropics-based animals typically don’t survive harsh winters, but they were reported as far north as Minnesota and as far west as Washington state, where winter temperatures have been rising in recent years.

From the 1960s until the 1980s, the demand from German markets had Louisiana exporting more than 1 million pelts per year. The high price for these animals greatly reduced their populations in the wild as hunters sought them for as much as $23 per pelt. After a steep decline in market prices in the 1980s and ’90s, wild nutria numbers increased, as did erosion of wetlands. Russian markets rebounded briefly in the late 1990s, when Louisiana trappers harvested and exported more than 670,000 in two years, but then demand steeply dropped again.

Also invasive in Great Britain, nutria were successfully exterminated in the wild in the late 1980s, but it wasn’t cheap. Authorities hired full-time hunters to do the job thoroughly. Perhaps considering this model, in 2002 the Louisiana Department of Wildlife and Fisheries put a bounty on the nutria, although their affected area is at least 10 times larger Great Britain’s. Rather than hiring a few people, the agency began crowdsourcing the extermination of nutria. It pays $5 per nutria killed by hunters and trappers who follow all the rules. The procedure includes completing an application, getting written permission to be on a property and identifying that property’s legal boundaries. The department’s report states that in 2016-2017, “216,052 nutria tails worth $1,080,260 in incentive payments were collected from 228 active participants.”

The hunters and trappers were also provided with fur and meat buyers. In a flyer promoting nutria as locally sourced nutrition, the department markets nutria this way: “Wild nutria are fussy herbivores, eating only the most nutritious parts of Louisiana plants. Their healthy diet gives you one too: high in protein and low in fat and cholesterol.” With very little fat, their flesh has been compared with rabbit meat. Check out this nutria recipe book from 1963 which includes notes from taste testers and instructions on how to prepare familiar dishes with this game meat.

What is the lesson here for small-scale, sustainable farmers? Consider that nutria’s reputation quickly turned from one of the best-selling farmed animals to one of the worst invasive species in the world. Be wary of unpredictable markets. Consider the decision the nutria farmers had to face in the 1930s. What would you do with your animals if there was suddenly no market for them and you couldn’t afford to keep them? How we manage the animals within our care affects not just our businesses, our families and our customers, but it could also disrupt fragile ecosystems that buffer our communities from natural disasters. There are many other examples of domesticated animals turned feral that have disrupted wild lands. Invasive species really are natural disasters that can be prevented.

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