How Did Nutria Become a Problem in South Louisiana?

Nutria is a species of rodent native to South America. It was introduced to southern Louisiana by way of Argentina in the mid 1930s when fur traders in the region began breeding them in captivity.

An accidental release occurred when an unnamed hurricane stuck the coast in 1940. Nutria began to populate the coastal marshes and inland swamps of Louisiana's coast, spurred by their prolific breeding patterns.

Coming to sexual maturity anywhere between 3 and 7 months, nutria have an average litter of 5 after a 130-day gestation period. Not only is the female typically ready to conceive again just 3 days after giving birth, but her young can also begin feeding upon vegetation just hours after their arrival.

The nutria population growth rate was so explosive that by 1955, the Louisiana Department of Wildlife and Fisheries (LDWF) estimated that there were already 20 million nutria in the state. With this rise in population, the damage they could inflict was rapidly being discovered as well. Rice and sugar cane, in particular, were among the nutria's first agricultural victims.

Despite a flourishing fur market that harvested 1.8 million nutria at its peak in the 1970s, a decline in demand has seen the annual harvest drop below 500,000 every year since 1988. The LDWF's data shows that when harvest levels decline below this critical half-million threshold, habitat loss is taking place.

Because they feed only on plant life, nutria feed on the very substance that holds marshes together. Besides eating green, leafy matter, nutria burrow into marsh soils to get at the roots of plants. And because root systems are the primary mechanism binding the marsh soil, their loss means that the soils then become highly vulnerable to erosion, the driving force behind Louisiana's coastal land-loss problem.