WETLAND DAMAGE

Vegetative damage caused by nutria has been documented in at least 11 Coastal Wetlands Planning Protection and Restoration Act (CWPPRA) project sites in the Barataria-Terrebonne Basins. The estimate of 80,000 acres of marsh damaged was conservative because only the worse (most obvious) can be detected from aerial surveys. The number of acres being impacted was certainly higher. Since the introduction of the Coastwide Nutria Control Program, the number of impacted acres has dropped to 23,141 acres. When vegetation is removed from the surface of the marsh, as a result of over grazing by nutria, the very fragile organic 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 thus lowers elevation. Frequently the plant's root systems are also damaged, making recovery through vegetative regeneration very slow.

The first coast wide nutria herbivory survey was flown in 1998 and continued through 2001, as part of the Nutria Harvest and Wetland Demonstration Program.  The Coastwide Nutria Control Program began in 2002.  Below are the total number of nutria damage sites and the number of acres documented for each year.

* When extrapolated to a coastwide estimate, the acres impacted over these years ranges from 102,585 to 23,141 acres (damaged acres x 3.75). The 3.75 multiplication factor comes from the area actually surveyed along transect lines (0.5 miles) and the distance between transect lines (1.87 miles).

Click below on images to see wetland damage caused by nutria.