Years ago hunters woke up and saw the link between healthy habitat and abundant wildlife. Now anglers are making the connection, noticing that lakes and streams with the best fishing usually have the healthiest fish habitat.
Unfortunately, that realization has come too late in many areas where habitat degradation has harmed fish populations. Pesticides, fertilizers, and soil from farm fields drain into lakes and rivers, killing aquatic insects, depleting dissolved oxygen, and smothering fish eggs. Leaves, grass, and fertilizer wash off urban and suburban lawns into sewers, then into lakes, where these excessive nutrients fuel massive algae blooms.
Even northern waters are losing fish habitat. The housing boom on fishing lakes is turning native lakeshore and shallow water vegetation into lawns, rocky riprap, and sand beaches. Few lakeshore owners realize that the native plants (the so-called "weeds") they Remove help sustain healthy fish populations. Within a few years, the water gets murkier from fertilizer runoff, and, lacking bulrushes and other emergent plants in shallows, fish have fewer places to hide and grow. The great fishing that drew people to the lake in the first place inevitably deteriorates.
Summing up the irony, one fisheries manager notes: "Lakeshore owners who don't see the connection between lakeshore habitat and fish populations too often end up wrecking the very thing they value.
But there is good news to report, too. Each year, we team up with a growing number of fishing clubs and lake associations to improve and protect fish habitat on dozens of lakes and streams statewide.
Aquatic plant restoration
To restore the natural features of lakeshores that provide fish habitat, fisheries managers work with local lakeshore owners on landscaping that's friendly to lakes. This new approach replaces some or all lakeside lawns and beaches with native wildflowers, shrubs, grasses, and aquatic plants. A growing number of lakeshore owners are learning that restoring natural vegetation can cut maintenance costs, prevent unwanted pests such as Canada geese, attract butterflies and songbirds, and improve fish habitat in shallow water.
In 1998, we established an Aquatic Plant Restoration Program. Working with local communities, program staff members have set up more than a dozen clearly marked demonstration sites near boat ramps and lakeside parks throughout the state. Here, lakeshore owners can see how their property might look with native vegetation. And they can learn where to get more information on habitat restoration. The program has also produced a "Save Your Shoreline" video available for loan to citizens and lake associations.
Spawning area improvement
Fisheries managers work to prevent eroding shorelines from sending sediment into the water, where it smothers fish eggs and the underwater insects that fish eat. They show willing landowners how state or federal conservation programs make it cost-effective to convert plowed land along the lake edge into grassy strips that filter runoff and stabilize banks. On some lakes, fisheries managers use backhoes to slope back steep banks and create a gentle contour less easily eroded. Then they restore the sloping bank with native grasses and trees that anchor the soil.
On some large reservoirs, such as Lake Winnibigoshish and Lake Lac qui Parle, fluctuating water levels can eat away at shorelines. Here fisheries managers install large boulders to shore up eroding banks. On Winni, more than 4.5 miles of the lakeshore has been reinforced since 1989. Walleyes are now spawning in the improved habitat.
Fisheries crews also alter water levels in marshy area used by northern pike for spawning to create more favorable conditions for reproduction.
River and stream habitat improvement
On large rivers, fisheries managers work with the staff of the DNR Ecological Resources Division to improve fish access to spawning habitat. On the Red River of the North, for example, several lowhead dams have been replaced with a series of rapids that allow fish to reach upstream spawning tributaries. On the Mississippi River near Lake City, fisheries managers have worked with the U.S. Army Corps of Engineers to alter water levels above and below lock and dams to improve habitat for northern pike and bluegills.
Working with other agencies and local units of government, we restore natural curves in river and stream stretches that have been straightened by artificial channels.
We also team up with anglers to make streams better places for trout by installing 20- to 40foot-long box frames, called lunker structures, where fish can hide from predators and grow larger. We also put boulders along eroding streambanks and add underwater rocks that force the current to deepen and scour streambeds.
Most stream habitat improvement occurs on private land stream easements. In exchange for a onetime payment, landowners allow us access to streams to do improvements and allow anglers access for fishing.
In southeastern Minnesota, we have secured stream easements on more that 40 percent of the trout stream miles flowing through private land.
Every few winters, most or all fish in many shallow lakes die for lack of oxygen. Called winterkill, this occurs when thick ice and snow block sunlight from reaching underwater plants. When the plants die, they decompose and use up dissolved oxygen needed by fish. Usually it takes three to four years for the lake's fish population to recover. The solution to this problem is remarkably simple: Add oxygen to the lake using an aeration system. One system uses a pump and baffle to draw water from the lake up onto shore, where it collects oxygen by cascading over boulders before returning to the lake. Another keeps an open area in ice where air can mix with water.
These and other aeration systems add enough oxygen to prevent winterkill. As a result, they provide fishing opportunities that otherwise wouldn't exist. Many southwestern Minnesota lakes that often lacked fish three years out of four now offer good angling year after year.
Most aeration systems are purchased by the DNR and installed and run by local conservation clubs and units of government in consultation with local fisheries managers. We help decide what types of systems would work best and where they should go, and we check them periodically to make sure the devices are working.
The first lake aeration systems were installed in the early 1960's. Today, roughly 270 of the systems are aerating shallow lakes. We approve approximately 12 new aerator permits each year, mostly in the Twin Cities Metro Region and southwestern Minnesota.
Fish habitat in many shallow lakes has been destroyed by carp and black bullheads. These fish root in the silty lake bottoms and stir up nutrient-laden sediment. The murky water blocks sunlight from reaching aquatic plants that stabilize the lake bottom and provide oxygen and habitat for game fish and water insects. Bluegills and bass numbers drop, while the seemingly indestructible bullheads and carp thrive in the gray-green soup.
The only way to begin restoring the ecological balance in these damaged lakes is to first remove all the offending fish. And the only proven method of doing that is to kill the entire fish population and restock the lake with game fish. This process is called lake rehabilitation.
The fish are killed by applying rotenone, a natural chemical derived from a South American tree. Rotenone kills gilled animals by preventing them from using dissolved oxygen. In the concentrations used by the DNR, it is harmless to humans or any wildlife that eat fish killed by the substance. Rotenone breaks down into carbon dioxide and water within a few weeks, rendering it completely harmless.
Lake rehabilitations aren't long-term solutions, however. Because the carp and bullheads eventually return to lakes through connected waters, many rehabilitated lakes return to their sorry state within 10 years.
The sediment that carp and bullheads stir up is loaded with nutrients from surrounding farm fields. And nutrients and other contaminated runoff flow into lakes from distant farms, parking lots, streets, and lawns. The nutrients fuel blooms of algae, which, when they die, consume oxygen needed by fish and underwater insects.
That's why fisheries managers increasingly focus on reducing the influx of this non-point-source pollution as part of a long-term solution to improving fishing in these lakes.
Aquatic Plant Restoration
Since 1991, we have been reestablishing emergent aquatic plants on Knife and Pokegama lakes in east-central Minnesota. High water, overabundant carp, and relentless waves had uprooted existing plants, which are important fish and wildlife habitat.
"The plants are taking hold," reports Jack Lauer, assistant fisheries supervisor at Hinckley, "but it's slow going."
Lauer and student workers have been transplanting hardstem bulrush, river bulrush, and giant bur red from nearby lakes to Pokegama and Knife. After obtaining a required DNR permit, the workers uproot the plants, transport them to the new lakes, and plant them in one- by three-meter plots. The plants are anchored with river stones and protected with windbreaks.
The emergent vegetation provides habitat for underwater insects that fish eat, nesting areas for crappies, sunfish, and bass, and spawning habitat for northern pike. They also protect windswept shorelines from wave erosion.
Sleepy Eye Lake
Before Sleepy Eye Lake near New Ulm as rehabilitated, its water in midsummer resembled pea soup. Biologists who lowered a black-and-white saucer-sized plate, called a secchi disc, into the lake watched it disappear from view just 2 feet below the surface. Anglers rarely caught anything but carp and bullheads. Swimming was not even considered.
Then, in 1993, we used rotenone to kill all the fish in Sleepy Eye and then restocked it with panfish, yellow perch, catfish, northern pike, and largemouth bass. With fewer carp and bullheads to stir up bottom sediment, the water has cleared. Today a secchi disc lowered 8 feet down is still visible. As a result of the clearer water, underwater plants are thriving and the fish population is booming. Northerns over 20 inches, bass and catfish up to 5 pounds, and good numbers of bluegills, bass, and crappies are caught regularly. Local kids say the swimming is awesome.
In 1992, the Minnesota Legislature created a new public land classification called aquatic management areas (AMAs). Modeled after wildlife management areas, AMAs are purchased from willing sellers to protect the environmentally vital shoreline and littoral (shallow water) edge of lakes, streams and rivers.
The focus of AMA acquisitions is critical shoreline habitat, muskellunge spawning areas, and walleye nurseries. Once purchased, the area are protected from development, pollution, and other damage.
Each year, we buy roughly 15 AMAs using money from the Environment and Natural Resources Trust Fund (state lottery), the Reinvest in Minnesota Critical Habitat match Program, and the Legislative Commission on Minnesota Resources. So far more that 100 AMAs have been purchased throughout the state.
Before the AMA acquisition program began, we had purchased more than 150 wetland fish spawning sites next to lakes and acquire more than 210 miles of easements along trout streams. In addition to providing access for angling and stream improvements, the brushy and grassy easements shade the water to keep it cold and filter out sediments flowing in from surrounding farmland.
Environmental review and watershed coordination.
It's far less expensive to protect fish habitat from harm beforehand than it is to repair the damage afterwards. That's the idea behind environmental review and watershed coordination. Fisheries managers and other DNR staff members scrutinize plans by developers, other agencies, and local governments to see if the proposed developments might damage nearby fisheries.
For example, a proposed golf course irritation system might suck away vital water from a trout stream, or a proposed resort expansion could irreparably damage a lake shoreline.
Each year, we review hundreds of development projects. By conducting these environmental reviews, we can head off potential disasters and offer suggestions to developers and others on how the plans might be revised to lessen harm to fish habitat and populations.
This "ounce-of-prevention" philosophy is also behind our decision to fund several DNR watershed coordinators, who work with citizens and local governments to protect water quality and fish habitat throughout Minnesota.
Moody and Gladstone Lakes AMA
In March 2000, we acquired a 195-acres parcel of land in Crow Wing County containing 3,700 feet of undeveloped shoreline on Gladstone Lake and an entire 40-acre pristine lake named Moody. The Moody and Gladstone Lakes AMA, says Brainerd area fisheries manager Tim Brastrup, "contains perhaps the last high-quality undeveloped shoreline of significant length in Crow Wing County." In addition to providing fish habitat, the aquatic management area provides bald eagle roosts, shore fishing access, "and a place to observe some of the most beautiful sunsets you've ever seen," says Brastrup.
The property was owned by Marie Malskeit, a lifelong landowner whose mother had been deeded most of the property from the Theodore Roosevelt administration in 1907. The elder Malskeit had instructed her daughter to eventually put the land into state ownership. Brastrup says Marie Malskeit, who had been a careful steward of the property, accepted less than the appraised value for the land, donating the $43,600 difference to the Reinvest in Minnesota (RIM) Critical Habitat Match Program, which was used to buy the property. Most RIM funds are generated by conservation license plates, which the state sells to buy important habitat for fish, wildlife, and native plants.