Conservation: An Otterly Amazing Comeback

With the help of scientists, wildlife managers and fishermen, the North American river otter has returned to many U.S. states, only to once again be fighting old adversaries

  • Anne Bolen
  • Conservation
  • Nov 07, 2011

THE RIVER OTTER'S PLAYFUL ANTICS of sliding down hills or wrestling with littermates can charm the most stoic of hearts (see video of otters playing below). Indeed, this endearing member of the weasel family is so vivacious that we might assume these North American inhabitants always have thrived and will continue to do so.

Yet by the early 20th century, unregulated trapping, habitat destruction and water pollution had caused the North American river otter to nearly disappear from much of the interior United States, with most of the remaining populations living in northern states and coastal environments. If it hadn’t been for revised management strategies and national legislation to protect waterways, a multistate reintroduction effort could not have restored the river otter to much of its historic range.

River otters need relatively clean wetlands, rivers and streams with plenty of prey and secluded places to den, such as former beaver lodges and riverbanks. So “otters are good indicators of what is in the water,” says Thomas Serfass, a wildlife ecologist at Maryland’s Frostburg State University.

Serfass was a young graduate student when he took on reintroducing river otters to Pennsylvania in 1982. By the 1950s, historic overtrapping, water pollution and loss of more than half of the state’s wetlands had reduced the state’s otters to one population in the northeastern Pocono Mountains. Working with the Pennsylvania Department of Conservation and Natural Resources, Pennsylvania Game Commission and other groups, Serfass chose seven tributaries in the central and western part of the state that he determined were able to sustain otters.

But Serfass felt the reintroductions would not be truly successful without the support of the surrounding communities. “When you are doing a reintroduction project, if you are doing your job properly as a biologist, you should interact with the local people,” says Serfass. “As a result, you learn about local attitudes and about the people who are interested in conservation.” While interviewing outdoor enthusiasts, he found that some anglers viewed the otters as a threat to their prized game fish. Then he discovered two who were kindred spirits: Tom and Debbie Finkbiner.

The Finkbiners operate their Slate Run Tackle Shop in Pine Creek Gorge, a mountainous woodland and network of rivers also known as the Grand Canyon of Pennsylvania—and the first otter release site. Since 1976, the couple has been giving advice about the best places to fish in this angler’s Mecca. “So when we approached people with an idea such as supporting reintroducing river otters to the area,” says Tom Finkbiner, “they trusted us to do what was right rather than something for profit only.” He listened to his customers’ concerns: “They thought that each otter would eat up to 50 pounds of trout!” Then he gave them the facts: “I told them they could only do that if they had refrigerators.”

Otters are top predators in river, lake and wetland ecosystems. However, Serfass had collected more than 400 otter scats from the Poconos to show anglers that while adult otters consume between one and two pounds of food a day, including some trout, they typically ambush slower-moving prey such as carp and suckers as well as amphibians, reptiles, insects and, one of their favorite foods, crayfish.

Serfass presented more than 300 slideshows about the otters’ varied tastes to sportsmen throughout the state. He and Finkbiner eventually gained most of the anglers’ support, and by 2003, the reintroduction program had released 153 otters relocated from the Poconos, nearby states and Louisiana. Serfass went on to help with otter reintroductions in Maryland, New York and New Mexico.

Since the U.S. reintroductions began in 1976, more than 4,300 river otters have been released in 22 states. As these animals tend to be elusive and have expansive ranges, confirming their location and numbers in an area is difficult. However, otters have been spotted or tracked with radiotelemetry or their paw prints and feces have been found in each of the states in which they were released as well as some to which they have migrated. Genetic testing by one of Serfass’s graduate students has shown, for example, that some otters from Minnesota have moved into North Dakota.

Now after nearly four decades of slow recovery, river otters continue to fight old adversaries—water pollution and shrinking habitat—only with less legal armament. The 1972 Clean Water Act was intended to “restore and maintain the chemical, physical and biological integrity of the Nation’s waters.” Yet Supreme Court rulings in 2001 and 2006 called into question whether small streams, headwaters and wetlands that are separate from “navigable waters” warrant federal protections. However, Nicole Duplaix, chair of the International Union for Conservation of Nature (IUCN)’s Otter Specialist Group, explains that because even small streams eventually feed into larger waterways, “All water is connected. The only time it is isolated is when you are drinking it out of a glass.”

Water pollution can be a real problem for otters. As in many states, some of Pennsylvania’s rivers contain pesticides and industrial pollutants such as polychlorinated biphenyls (PCBs) and mercury. The otters’ prey can absorb these chemicals, which can then accumulate in the otters. The Pennsylvania Department of Environmental Protection reports that acidic fluid draining primarily from abandoned coal mines is in at least 5,500 miles of Pennsylvania’s tributaries, and silt from mining, development and agriculture has impaired nearly 9,000 stream and river miles. Now, a recent resource rush to drill for trillions of cubic feet of natural gas thought to be beneath two shale formations could increase the amount of silt sliding into the state’s waterways. The shale stretches from New York down to Tennessee and under all of Pennsylvania’s otter release sites. As acid mine drainage kills aquatic life and siltation smothers insects and algae at the bottom of food chains, this pollution can “limit where the otters can expand to and thrive,” explains Serfass.

Both Serfass and Duplaix say the fate of even historically stable otter populations should not be taken for granted. For example, most of the reintroduced otters were from coastal Louisiana, which was awash with Gulf of Mexico oil in 2010. “We don’t know the impact of the oil spill on otters in that area,” says Serfass. “But this indicates how quickly a thriving population could potentially be impacted by an unexpected event.” Duplaix agrees: “Unusual weather events or accidents like oil spills or leachate from mining are never factored in when a law is changed or when regulations are weakened.”

In April 2011, the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers proposed a Clean Water guidance that would restore Clean Water Act protections for millions of wetland acres and tens of thousands of stream miles nationwide. This guidance has yet to be finalized and implemented. The river otter may not have time to wait. As Duplaix points out, this North American icon “can be easily wiped out one watershed at a time.”

How anglers have helped the otters  by sharing their fish with them may yet be fully realized. But that is fine with Tom Finkbiner. “A lot of the decisions that I’ve made on conservation issues are not based on us. They are based on future generations,” he says. “I think it is wonderful to leave an area to those unborn outdoors people.”

The Dirty Water Bill

In July 2011, the U.S. House of Representatives passed H.R. 2018, a bill that some have deemed the “Dirty Water Bill.” If enacted, “This bill would take away the Environmental Protection Agency’s ability to oversee state compliance with the Clean Water Act and to stop large-scale wetland destruction,” says Jan Goldman-Carter, NWF’s senior manager of wetlands and water resources. To read more about NWF’s work to ensure healthy aquatic ecosystems, visit

Video of otters playing by Sadie Stevens, Department of Environmental Conservation, University of Massachusetts Amherst

Anne Bolen is managing editor of National Wildlife magazine.

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