Walleye Habitat

Walleye are found in a variety of habitats across Wisconsin. They inhabit rivers, reservoirs and lakes. They were native to the major drainage systems of the state and were stocked into many land locked lakes. In some lakes they have spawned successfully and have developed self sustaining populations. Other lakes apparently have either poor spawning habitat or inadequate food supplies to spawn successfully. Walleye are most common in larger lakes (more than 500 acres) and the larger river systems of the state and are not common in lakes under 100 to 200 acres in size.

Spawning Habitat

Spawning habitat may be the most critical bottleneck in the life history of walleye. Walleyes spawn over a variety of habitats including, gravel, cobble rip-rap and flooded vegetation. The life history of walleye is that of a long-lived species which produces a large number of small eggs each year that are broadcast across suitable habitat with no further parental care. Habitat, weather, predation, and the availability of suitable food items for the young walleye affect the success of walleye reproduction each year. The most important spawning habitat in lakes is wind-swept gravel and cobble shorelines. Walleyes may spawn on rock reefs away from shore if the bottom surface consists of clean rock or gravel. Shallow water is preferred because wave action is able to keep the rock surface clean and many crevices form between rocks. The eggs initially stick to the rock surface until they become water hardened. The eggs then fall into crevices between rocks where they are protected from predation and abrasion. Water levels are critical during spawning and egg incubation for access to the rocky areas. The eggs perish on sand or silt bottoms. Walleyes sometime move into streams and rivers that flow into or out of lakes to spawn over gravel or rock bottoms. The eggs are deposited, harden and then drop into the crevices. The eggs are protected during incubation and the fry then move into the lake where they feed on zooplankton and small insect larvae.

Migration

Walleyes migrate up to 100 miles or more in larger river systems such as the Mississippi, Fox and Wolf Rivers to find suitable spawning habitat. Walleyes spawn in flooded marshes along the Fox and Wolf Rivers. They seek out marshes where water flows through the marsh providing adequate oxygen levels. Water levels must be high enough during the incubation period to allow the fry to hatch and quickly move into the river. Walleyes in the Mississippi River use both rocky areas and flooded vegetation. Dams can prevent spawning migration to prime habitat on some river systems.

Larval and Young Walleye

Survival of larval and young walleye also represents a critical bottleneck. The number of young that survive from eggs produced in a given year (a year class) is highly variable from year to year. Most years do not produce a large year class, in fact, only one year in four or five may be successful and contribute significantly to the adult population. Larval and young walleye must successfully avoid being eaten; their switch from yolk sac to feeding on their own much match the timing of the increase in plankton prey in the spring; later in the summer, small prey fishes must be available at the time when young walleye switch from a diet of plankton and insects to one of fish; and the young must avoid predators and have sufficient reserves built up by fall to survive the first winter. The odds of survival for any one walleye are very small.

Juvenile Habitat

Little is know about the habitat requirements of juvenile walleye. Food sources probably determine where they are found. Escapement cover may be important but, they are commonly found along shore areas at night.

Adult Habitat

Adult walleyes utilize a variety of habitats. Water clarity or light penetration probably determines where they are found during daylight hours. In very turbid waters they are sometimes found in very shallow areas during the day. In clear water they generally move to deeper water or in the shade of woody debris and vegetation. Divers have found walleyes laying in the shade of submerged structure and aquatic plants during daylight. At night they move to areas where food is available. Those areas include shallow shorelines, reefs, weed lines and mud-flats.

Water Quality

Water quality is important to walleye populations. While they can thrive in turbid waters, they must have adequate oxygen supplies to survive. They are generally considered a cool water species but also inhabit shallow reservoirs that have fairly high summer temperatures.

Improving Walleye Habitat

Efforts to improve walleye spawning habitat have had varying degrees of success. There are several methods including:

• placement of course gravel and cobble
• management of marsh vegetation
• water regulation laws.

The most common method of habitat improvement in lakes has been the placement of course gravel and cobble along windswept shorelines. The east shoreline is generally the best location because prevailing winds wash the shoreline and keep the rock and crevices clean. Rocks with high calcium content such as limestone should be avoided since algae tend to thrive on the surface of such rock. Granite type rocks are a better choice. Water level management is important to the success of such efforts.

Management of marsh vegetation is of great importance in those river systems where the walleyes spawn over flooded vegetation. The promotion of grasses rather than woody vegetation is one key element. The other key is to direct sufficient flow into the marshes so the eggs are well oxygenated and the fry can escape the marsh with the flowing water after hatching.

Protection of key spawning habitat throughwater regulation laws is an important aspect of walleye management. These laws protect the nature of the shoreline, water levels and wetlands. Shoreline protection efforts should be limited to the use of small rip-rap rather than sea-walls. Sand blankets can also destroy important rocky habitat. Wetlands in the watershed need to be protected so that water levels are sustained over a longer period of time rather than rising and falling quickly. The protection and enhancement of suitable habitat for spawning, growth, and survival are key factors for ensuring abundant walleye populations and balanced aquatic communities into the future.