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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

© Mark Cupp, Lower Wisconsin Riverway Board
From the dam at Prairie du Sac to its confluence with the Mississippi River, the riverway corridor protects bluffs, bottomland forests, backwaters and 98 of Wisconsin's 147 fish species.

© Mark Cupp, Lower Wisconsin Riverway Board

August 2005

A long stretch of wonder

92 miles of sandbars, driftwood and diversity, the Lower Wisconsin State Riverway provides an escape for humans and a safe haven for rare fish.

Dave Marshall

Fluid habitat, numerous niches
The value of a wild river
Lower Riverway residents

One evening last September, Chuck and I headed upstream in my 14-foot fishing boat from Lone Rock on the Lower Wisconsin River. Five other dudes were canoeing downstream from Spring Green and our goal was to meet on one of the scores of sandbar islands to celebrate the end of Steve's long bachelorhood.

Navigating the Lower Wisconsin River is always a challenge. While the river is wide, a much narrower deep channel meanders back and forth, reflecting from shore to shore along its course. Well hidden within the dark water are broad shallow sand flats. If you don't read the river well, you'll suddenly be beached on a sandbar and find it's too late to change course. You'll end up hopping out and walking the flat, pulling the boat behind you, until you reach a drop-off at the edge of the deeper channel.

Forty-five minutes after we launched, Chuck and I found bachelor Steve, his brother Jeff, and the rest of the group already set up on a sandbar for a barbeque. We quickly settled in and enjoyed a few cool ones with grilled steak. Darkness was fast approaching and we gathered driftwood probably deposited when high water receded from this sandbar after the last spring flood. The river's endless motion continually eats away at sandbars, eroding some islands while simultaneously building others. Driftwood lines the riverbanks and the island shores, its source the dense floodplain forest. Trees fall into the water in an infinite process; the downed trunks and branches provide basking habitat for rare Blanding's and map turtles while catfish hide below the submerged logs.

The fire crackled in the dark. Between Chuck's guitar and song, the yarns flew higher and more numerous than the mosquitoes in the crisp night air. Steve, Dave S., Jeff, Paul and John had paddled the river many times before. They share both personal and professional connections with the river, with technical backgrounds ranging from water chemistry to wildlife and fisheries research. In the quiet night, we heard fish frequently break the surface. A few of us fantasized about lunker smallmouth bass feeding at the surface. John wasn't sure, given the vast array of fish species living in the river. He's a fisheries scientist and curator of fishes at UW Madison Zoological Museum. John Lyons knows as much about what swims in this river as anyone. He has surveyed fish populations here for more than two decades and this river holds more fish species than any other lake or river system in the whole state.

Each year more than 400,000 people visit the Lower Wisconsin and explore the 92-mile-long stretch of water bisecting the hills and valleys of southwestern Wisconsin. They come to bird watch, boat, camp, canoe, hunt or play. They especially fish for a variety of sportfishes, including smallmouth bass, walleye, sauger, channel catfish and monster-sized flathead catfish. Everyone enjoys the scenic beauty of a river reach little changed since Native Americans and French explorers canoed its waters centuries ago, but most are unaware the Lower Wisconsin Riverway is also a storehouse of rare fish and other biological treasures.

Fluid habitat, numerous niches

Unlike many rivers and lakes whose shorelines become paved, tamed or manicured as part of a suburban homeowner's view of nature, the Lower Wisconsin River's wild character and wildlife habitats have been and will continue to be preserved through a number of state and local programs. Enacted in 1989, Wisconsin Act 31 created the Lower Wisconsin State Riverway and a Riverway Board to preserve the scenic beauty and natural character of the river. This public-private partnership protects about 77,300 acres of land along the 92-mile river corridor. History, recreation, outstanding game fish populations and biodiversity are all preserved here. As a result, the Lower Wisconsin River has largely escaped manmade disturbances and sustains the intricate web of interdependent relationships woven over thousands of years. Importantly, this stretch of river never has been dammed, and that good fortune has both defined its nature and preserved its unique inhabitants.

Some of the most interesting and unusual fish species in the upper Midwest dwell within the dark river waters or in the many connected floodplain lakes. The Lower Wisconsin Riverway provides a safe haven for rare and unusual species at a time when researchers are discovering alarming declines in the numbers of fish species and other aquatic organisms around Wisconsin brought about by intensive agriculture, heavy development and urban sprawl along riverbanks and lakeshores. In our zeal to live our lives ever closer to the water's edge we are collectively loving it to death.

Not so here. The Lower Wisconsin River shorelines are still a mix of undeveloped woodlands and prairies. The river's free-flowing channel, braided by scores of islands and sandbars, has countless connections with off-channel sloughs and wetlands. These mostly intact habitats preserve scenic and historical values as well as the unique ecological character of this important river.

Abundant fish, mussels, turtles and aquatic insects thrive in this blend of river and off-channel habitats. Of the 147 native fish species found in Wisconsin, Lyons has documented 98 native species from the Lower Wisconsin Riverway alone.

"The Lower Reach is among the least disturbed parts of the Wisconsin River and is one of the highest quality large warmwater river reaches remaining in the United States," he says. "The high diversity of fishes we find here reflects the natural riverine and off-channel lake habitats that would be destroyed if this section of river were dammed." Included in his list of fishes are ancient forms such as the silver and chestnut lampreys, shark-like paddlefish, lake sturgeon and shovelnose sturgeon, and the air-breathing gars and bowfin. Based on fossil records, some of these "living fossils" are nearly identical to their 100 million-year-old ancestors. Other unique and interesting fish include blue suckers, mooneyes, shoal chubs and western sand darters. Lyons notes the rare blue sucker, one of many riverine species adversely affected by dams elsewhere, is commonly found in the Lower Reach; the species inhabits deep swift channels and little is known about its breeding habits. As its name suggests, the western sand darter lives on the broad sand flats and literally dives into the sand as an escape mechanism.

The off-channel sloughs contain a different fish assemblage better adapted to lakes or slow current. Each one is somewhat unique with different ratios of lake and riverine fish populations. Over the last few years, I have tried to build on the state's knowledge base of Lower Wisconsin Riverway fishes by sampling the off-channel floodplain lakes and sloughs. Two or three days at the end of each summer, we sample several of these backwater lakes; some that have not been sampled in decades while others have no sampling records. Using small-mesh seines and towed electroshocking gear, we find surprising populations of state-endangered starhead topminnow within the blankets of aquatic plants and woody snags. Other small rare species are frequently found, including least darters, pirate perch, mud darters and lake chubsuckers. These species simply don't survive in waterways with shores altered by development.

"Many of the rare fishes inhabiting both the main river channel and backwater sloughs are on the northern edge of their range where evolution is occurring," Lyons says. "We have a moral obligation to ensure our actions do not destroy these unique biological treasures so future generations can enjoy them. These 'invisible' fishes are generally off the public sonar screen but tell us important lessons about habitat and water quality. Habitat-sensitive species are usually the first casualty of highly manicured fussy shorelines, but they foreshadow declining gamefish growth rates and numbers."

© Robert Queen
Biologists collect samples of fish and other aquatic life in the river's marshes, bays and backwaters that provide a nursery to many rare fish species.

© Robert Queen

Living in close association with fish are numerous mussel species found in the Lower Wisconsin. DNR Fisheries and Freshwater Mussel Biologist Kurt Welke fires off a litany of mussel names like monkeyface, black sandshell and round pigtoe that frequent the Lower Reach.

"At least 10 state-threatened or endangered mussels are found in the Lower Wisconsin River," he says. "Their existence depends on the presence of specific fish hosts that complete their life cycle. The relative high diversity of mussels is directly linked to high fish diversity, and ultimately to the high-quality riverine habitat found in the Lower Reach." When mussels lay eggs, the small worm-like larvae that develop attach to the gills of specific fish species. Mussels are completely reliant on those fish to carry and deposit their larvae so mussel populations can grow in new areas. The fish-mussel association is just one example underscoring the importance of biodiversity, and how the loss or decline of a single species can have cascading effects on others.

In addition to fish and mussels, the Lower Wisconsin River hosts numerous rare mayflies and other aquatic insects. William Hilsenhoff, former University of Wisconsin aquatic entomology professor, described the Lower Wisconsin River as a "refugium for unusual and rare insects." His description could aptly apply to other animal groups, including mussels, fish and turtles.

The value of a wild river

The future of the Wisconsin River was not always bright. By the early 1970s, poorly treated wastewater from paper mills and sewage treatment plants in northern and central Wisconsin released more than 500,000 pounds of pollutants into the upper river each day. Large sections of the river were devoid of oxygen and fish. At times the river appeared more solid than liquid: dense clouds of paper fibers and rafts of fungi and bacteria, the "sewage slime growths" that thrive in severe pollution, choked its waters. Without witnessing the degraded conditions firsthand it is difficult to imagine just how polluted the upper Wisconsin River was. The federal Clean Water Act and state environmental protection programs came to the rescue. By the early 1980s, 95 percent of the pollution was reduced and the upper river greatly improved.

The Lower Wisconsin escaped the severe water quality problems the upper reaches experienced due to its remote location from industrial pollution sources. The Lower Wisconsin did ultimately benefit from the water pollution controls upstream, and improved water quality downstream was one of the main reasons recreational use of the river increased.

"As humans, we have the means to destroy or preserve this unique ecosystem," Lyons says. Thanks to these combined efforts – the Clean Water Act, Public Trust Doctrine, public lands management, and the Lower Wisconsin Riverway Board, the Lower Wisconsin and its biological diversity have been preserved so far. This stretch of river, in addition to offering important recreational opportunities, will continue to provide a vital link to Wisconsin's biological heritage – and serve as a benchmark for efforts to protect and restore other rivers.

Well after midnight that evening last September, Chuck and I headed back downstream as the others retired for the night on the sandbar. Navigating the river at night is indeed an adventure. Even the bright moon did little to help our visibility as mist rolled off the water and the river gave up its heat to the cold night air. As we carefully moved downstream, I thought about the growing popularity of places like the Boundary Waters and the Sylvania Tract as northern and rural Wisconsin become more developed. The Lower Wisconsin River may lack remoteness from civilization, part of the allure of these other places, but the river makes up for its nearby location with a rich diversity of fish and other organisms the northern climates can't support. Just a short distance from southern Wisconsin towns and cities, in the midst of bigger "attractions," the Lower Wisconsin State Riverway remains a slice of wilderness and adventure within tamer surroundings.

Dave Marshall is a fisheries biologist stationed at DNR's South Central headquarters in Fitchburg.