Reviving River Otters: How Human Intervention has led to a Comeback of these Keystone Species
By: Noah Weiser
During the late eighteenth and early nineteenth centuries, river otters and other Rocky Mountain wildlife faced severe challenges because of the rapid increase in industrialization and development in the region. Mining, agriculture, and ranching significantly polluted and destroyed the clean waterways that otters and their prey, including fish, crustaceans, and amphibians relied on. In addition to population loss due to environmental degradation, otters were hunted to extirpation, meaning they were extinct from the region, because their pelts were even more valuable than beavers’ because otter fur is softer and denser. In 1907, the last confirmed river otter siting occurred in Colorado. For almost seventy years, there were no otters in Colorado.
However, a policy shift occurred in the early 1970s. In 1973, the Colorado Division of Wildlife through the Wildlife Commission began to protect all nongame species as well as threatened or endangered wildlife. This huge transition in environmental policy protected iconic Rocky Mountain species, including the Canadian lynx, black-footed ferret, boreal toad, cutthroat trout, and lesser prairie chicken. In 1975, Colorado designated the river otter as endangered in the state, and the Parks and Wildlife Commission was tasked with maintaining “species or subspecies of wildlife indigenous [to Colorado]. . . .” the governing statute, CRS § 33-8-101-110, directed the “Colorado Department of Wildlife to manage all nongame wildlife for human enjoyment and welfare, for scientific purposes, and to ensure their perpetuation as members of ecosystems.” From 1976 to 1991, over one-hundred otters were reintroduced across seven rivers and their tributaries including the Upper Colorado River, Dolores River, San Miguel River, Yampa River, and Green River. Paralleling Colorado, the Utah Department of Wildlife Resources reintroduced sixty-seven otters close to the border between Colorado and Utah. This project has helped re-establish an otter population in the Green River region.
The reintroduction of otters in the Rocky Mountain region has been such a great success that, in 2003, otters’ status was downgraded from endangered to state threatened. And in recent years river otter populations are doing very well. One of the most exciting moments occurred a few years after otters were no longer considered threatened. Bureau of Land Management employees spotted otters in the Rio Grande along the border with New Mexico. While there had been recent rumors of otters in northern New Mexico, this was the first confirmed siting, and many conservationists were excited that otters had spread to this new area.
River otter reintroduction has been a huge success story in American wildlife conservation efforts. Reintroduction efforts throughout the country have resulted in outstanding success because river otters are an extremely adaptable species. Louisiana river otters were released throughout the upper Midwest region, and today, river otters can be found in all lower forty-eight states and Alaska. Even better, there is currently no sign of decline on population.
Today, river otters are listed as a species of least concern with stable populations. River otters go hand-in-hand with healthy waterways. River otters are considered a riparian keystone species. Their impact on Rocky Mountain ecosystems helps to keep other aquatic populations in check. They are a terrific indicator species. River otters let officials know when a waterway is suffering because otters depend on long, contiguous stretches of river with good water quality and high prey biomass. While otters are a robust and adaptable species, their prey species are not. When their ecosystems are impacted by climate change and pollution otters can become impacted as well. Saltwater intrusion in coastal regions such as Louisiana has impacted otters living in marshes near the coast. While otters are on the rebound in the Rocky Mountain region and throughout the United States, their fate still lies in the hands of humans as development and climate change re-shape their ecosystems.