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River Friends
Why the return of otters to the lower Milwaukee River is good news for all species.

Photo by Stepan Jezek via Shutterstock
STRONG PAWS The river otter prospers in both frigid and sun-baked climates.

On May 28, 2012, a North American river otter swam within range of an underwater video camera near the Mequon-Thiensville Fishway, a channel that allows fish and other creatures to bypass a dam crossing the Milwaukee River in Ozaukee County. The image from that camera – which has also captured snapshots of giant brown trout, Chinook salmon and paddling turtles – pleased William Wawrzyn, a fisheries biologist with the Wisconsin Department of Natural Resources. “Better water quality over the years has resulted in more abundant and diverse fish populations in the lower river reaches,” he says of the Milwaukee River, and one of the fish’s top predators “may be responding in kind.”

Otters are a rare sight in southeastern Wisconsin after decades of urban development and water pollution, but they once roamed freely across the state. Wisconsin might even have been called the “Otter State” because the river otter, along with beaver and mink, were prime targets of the early fur trade. Otters are even relatives of badgers – both are members of the Mustelidae family of mammals.

Should a river otter ever venture into the city of Milwaukee, as happened recently in San Francisco, it would signal a reclaiming of the once-clean rivers that helped give our home its name. Perhaps you’ve heard that “Milwaukee” comes from a Native American word meaning “gathering place by the waters.” Otters are sensitive to environmental degradation, including that caused by mining.

No recent confirmed sightings of otters have been documented in Milwaukee or even Milwaukee County. But unconfirmed otter tracks have been sighted along the Milwaukee River just north of Riverside Park and in Estabrook Park, reports Timothy Vargo, manager of research and citizen science at the East Side’s Urban Ecology Center.

Most abundant in the northern half of Wisconsin, river otters are legally trapped for their fur pelts, and at least part of the steep decline in the animal’s numbers can be blamed on overharvesting. According to the DNR, there were 14,000 otters in Wisconsin in 1994, but by the fall of 2007, the population had fallen to 8,600, far below the DNR’s ideal figure of 13,000. In more recent years, the agency has reduced the number of otter-trapping permits available, and officials estimate that otters made a slight rebound in 2012 to about 10,300.

The primary causes of otter decline, according to the DNR, are loss of wetland habitat (especially wetlands created by beaver ponds) and human development. John Olson, a furbearer specialist at the DNR, says the department is considering shortening the beaver trapping season, both to preserve beaver ponds and to reduce the accidental trapping of otters. Almost 300 otters were killed “as incidentals” in the 2011-12 season, with most dying as a result of beaver traps.

River otters can grow to be 4 feet long and as heavy as 25 pounds due to their long, muscular tails. They primarily feast on fish, along with the occasional mouse or small rodent. On snow, they like to use their bellies as toboggans, both to save energy and perhaps for the fun of it.

Within the lower Milwaukee River, the biggest threat to otters and other fish-eating mammals, including humans, remains the Cedar Creek Superfund site in Cedarburg, Wawrzyn says. The site continues to release PCB’s into the creek and river from former industrial properties, according to DNR data.

In the meantime, look for the second coming of the river otter along the wilder parts of the Milwaukee and Menomonee rivers in Milwaukee County, especially near dusk or dawn. Its return will mean we’re doing something right.

This article appears in the April 2013 issue of Milwaukee Magazine.
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