Walleye

Characteristics

Large, whitish glossy eyes and strong canine teeth. A brassy olive-buff color, sometimes shadowing to yellowish sides and white beneath. The caudal fin has a silver or milk-white tip on the lower lobe. There are no distinct dark bars or mottlings on the sides of the body, but instead an overall mottling of brown or black. Spots on the anterior dorsal fin are lacking, but there is one large dark spot or blotch near the base on the last 2 to 3 spines of the posterior dorsal fin. There are 19 to 22 soft rays in the dorsal fin and 12 to 14 in the anal fin. The lateral line has 80 to 89 scales. The cheeks are sparsely scaled.

Distribution

Statewide; abundant throughout the Mississippi and Missouri rivers. Occasional to common in all of Iowa’s major interior river drainages including the Big Sioux, Cedar, Des Moines, Iowa, Little Sioux, Maquoketa and Wapsipinicon, as well as in Iowa’s natural lakes. It has been successfully stocked in the larger man-made lakes and river impoundments throughout Iowa.

Foods

Mostly fish such as Yellow Perch or Gizzard Shad; other aquatic animals such as crayfish, frogs, snails, and insect larvae

State Record

14 pounds, 8 ounces - Des Moines River, Polk County, September 1986 - Gloria Eoriatti, Ankeny, Iowa

Expert Tip

Backtrolling the upstream side of the Mississippi River wing dams using crankbaits can provide sizzling Walleye action. Fall fishing for Walleye on Iowa's interior rivers can be outstanding; cast a crankbait into shallow water and pull it back across the sand into deeper water - then hang on.

Details

The Walleye is the largest member of the perch family, weighing over 20 pounds. Its size, sporting qualities and delicious flesh make it one of the most important game species in North America.

Walleye are most abundant in large, cool, sandy-bottomed lakes, reservoirs or impoundments, but also lives in small lakes and large streams in smaller numbers. It is a highly migratory fish and can be found in lower reaches of small tributaries to large rivers. In rivers, Walleye are usually found at the bottom of deep pools with large boulders or submerged logs, but migrate to shallow waters at night. In large northern lakes, it spawns over bars or shoals.

Walleye reproduce in both streams and lakes in Iowa, but they are also hatchery-propagated in large numbers at the Spirit Lake and Rathbun Fish Hatcheries. Shortly after the ice melts from the lakes and rivers and the water temperature reaches 45 to 50 degrees, Walleye move into the shallows to spawn. Actual spawning takes place at night. The adult female moves to a spawning area where her arrival is awaited by males. The spawning area may be a smaller tributary stream, a shallow area in a river or a shoal in a lake. It is usually an area with clear water, 1 to 5 feet deep, and the bottom is covered with rubble or gravel. The area is likely to have current, the result of either flowing water or wave action. If such conditions do not exist, the adult fish use other spawning areas, but egg and young survival will suffer. Spawning activity takes place over about 3 weeks, with the peak last 7 to 10 days.

Generally, a large female is accompanied by several smaller males across the spawning ground in erratic and thrashing movements, with eggs and milt released at the same time. About 95 percent of the eggs are fertilized as they sink to the bottom. Individual eggs lodge in rubble or gravel crevices where they will be protected and  water can circulate, keeping them silt free and oxygenated. No protection is provided by the parents. Adults return to deep water after spawning is complete.

The number of eggs individual females produce varies according to body size and physical condition, but normally is 23,000 to 50,000 eggs per pound of fish weight. Incubation lasts 12 to 18 days, depending upon water temperature. Under the best of conditions, 5 to 20 percent of the eggs will hatch. Cold weather, which delays hatching, extremely heavy wind action or currents, which might wash the eggs ashore, and muddy water, which coats the eggs with silt, are prime factors that decrease hatching odds.

Upon hatching, the newborn fry is about 1/2 inch long and paper thin. For several days it will drift about, absorbing the yolk sac and gaining strength. Immediately after the yolk sac is absorbed, the fry starts to eat. At first, only the tiniest planktonic organisms are eaten, but as the fish grow, cladocerans and immature aquatic insects are eaten. Small fry are sometimes seen in schools on the spawning grounds, but soon disperse. After the fish reach about 2-inches long, they start to add small fish, minnows, Yellow Perch, suckers, and Bluegill to their diet. Adult Walleye eat large quantities of fish, sometimes feeding upon them almost entirely. Yellow Perch make up a big part of the Walleye diet in the natural lakes. Gizzard Shad are the most important forage source in the flood control reservoirs and the Great Border Rivers. Crayfish, frogs, snails, and insect larvae are also eaten at times.

Walleye are fairly easy to propagate and raise in hatcheries. Nearly 125 million walleye fry are produced each year to stock larger lakes and reservoirs throughout Iowa. A smaller number are also raised to fingerling size in shallow nursery lakes and concrete raceways before stocking. Walleye usually reach 5.5-inches long the first year and about 9.3, 12.4, 15.2, 17.4, 19.2, 20.6, 21.7, 22.1 and 23.2-inches in the next 8 years. Females grow faster and reach a larger maximum size than males. Larger fish have been reported in netting operations for brood fish from Rathbun Lake, Spirit Lake, West Okoboji Lake and Clear Lake.

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames

Illustration by Maynard Reece, from Iowa Fish and Fishing