Stizostedion vitreum
Walleye

Name:

• Stizostedion, "pungent throat"
• vitreum, from the Latin, "glassy", referring to the large eye
• Common name from the pearlescent eye, caused by the tapetum lucidum, a reflective layer of pigment that helps the fish to see and feed at night or in turbid water.
• Other common names include: Blue Pike, Core, doré (Fr), Dory, Glass-Eye, Grey Pike, Green Pike, Jack, Jackfish, Jack Salmon, Marble-Eye, Pickerel, Pike, Pike Perch, Sauger, Susquehanna Salmon, Walleye Pike, Wall-Eyed Pickerel, Wall-Eyed Pike, Wall-Eyed Perch, White Eye, Yellow Pickerel, Yellow Pike, Yellow Pike Perch, Yellow Walleye.

Taxonomy:

• Kingdom Animalia
• Phylum Chordata, animals with a spinal chord
• Subphylum Vertebrata, animals with a backbone
• Superclass Osteichthyes, bony fishes
• Class Actinopterygii, ray-finned and spiny rayed fishes
• Subclass Neopterygii
• Infraclass Teleostei
• Superorder Acanthopterygii,
• Order Perciformes, perch-like fishes
• Suborder Percoidei
• Family Percidae, true perch
• Genus Stizostedion, pike perch
• The perch family is a large one, with about 140 species in North America alone. The Walleye (Stizostedion vitreum) is a close relative of the Yellow Perch (Perca flavescens), Sauger (Stizostedion canadense), and the darters.

Description:

• Largest member of the perch family
• Length 13"-25"
• Weight
• averages 1-2 lbs in most waters
• occasionally exceeds 10 lbs
• females grow more rapidly and attain a larger maximum size than males
• Coloration
• highly variable, depending on habitat; usually paler with less obvious black markings in turbid waters, more strikingly marked in clear water.
• dark olive brown to yellowish gold sides, often marked with brassy flecks
• underside white
• no distinct dark bars or mottlings on the sides of the body, but instead an overall mottling of brown or black
• no spots on forward dorsal fin; one large dark spot or blotch near base on the last 2-3 spines of rearward dorsal fin.
• lower tip of the tail fin white
• young usually have dark blotches across their backs and down their sides, patterns usually absent in adults.
• Body
• torpedo-shaped
• dorsal fin of 19-22 rays
• anal fin of 12-14 rays
• lateral line of 80-89 scales
• Head
• eye pearlescent, a result of the tapetum lucidum, a reflective layer of pigment that helps the fish to see and feed at night or in turbid water.
• strong canine teeth
• cheeks sparsely scaled
• Lifespan
• about 7 years, most often caught as 1-3 lb three-year-olds
• maximum 10-12 years in south to perhaps over 20 years in the north.

Identification:

• unlike the sauger, the walleye lacks spots on its dusky dorsal fin, except for a dark splotch at the rear base of the fin, a marking the sauger does not have. The lower tip of the walleye's tail is white, unlike the all-dark lower lobe of the sauger.
• two distinct fins on its back, the first featuring large spines.

Distribution:

• Native to most of Minnesota, flourishing in large, shallow, windswept lakes with gravel shoals, such as Mille Lacs, Leech, Winnibigoshish, Upper and Lower Red Lake, Lake of the Woods and Lake Vermilion. It is also native to many smaller lakes and steams in all of Minnesota's major drainages. Because of its popularity as a game and food fish, the walleye was introduced to many other lakes, where it has become established. The walleye now occupies about 1,700 lakes totalling 2 million acres and 100 warm-water streams totalling 3,000 miles.
• Dominant in the fish fauna of central Canada, particularly the boreal forest zone. Inhabits tributaries of the St. Lawrence downstream to the Manicouagan, north to the east coast of James Bay; northwest from the Hudson Bay coast in Ontario and Manitoba to Athabasca, Great Slave and Great Bear lakes down to the Mackenzie River's delta; south through the Peace River drainage of northeastern British Columbia; and south, east of the Rocky Mountain foothills, to southern Alberta.

Habitat:

• A "cool-water" species, preferring warmer water than trout and cooler water than bass and panfish.
• usually over firm bottom such as sand, rock or gravel; occasionally near vegetation but not in it.
• The special layer in the retina of the eye tapetum ucidum, being extremely sensitive to bright daylight intensities, restricts feeding to twilight or dark periods. Walleye are tolerant of a great range of environmental situations, but appear to reach greatest abundance in large, shallow, turbid lakes. Large streams or rivers, provided they are deep or turbid enough to provide shelter in daylight, are also preferred habitat of the walleye. They use sunken trees, boulder shoals, weed beds, or thicker layers of ice and snow as a shield from the sun.

Food:

• Primarily other fish, such as Yellow Perch (Perca flavescens), Lake Whitefish (Coregonus clupeaformis), and minnows, as well as insects. If fish and insects are scarce, it also consumes snails, frogs, and small mammals.
• Diet shifts rapidly, from invertebrates to fishes, as the walleye increase in size. During the first six weeks of life their diet consists mostly of copepods, crustaceans, and very small fish. They can be cannibalistic, especially if small yellow perch or other forage fish are not readily available. Some populations, even as adults, feed amost exclusively on emerging larval or adult mayflies for part of the year.
• Yellow perch and cyprinids are particularly favoured when these species are present. Other food such as crayfish, snails, frogs, mudpuppies, and rarely small mammals may be taken, but usually only when forage fish and insects are scarce.
• Northern Pike (Esox lucius) is probably the dominant predator of the walleye over much of its range. Northern also an important competitor because it is the only other major, shallow-water predator in the north. Adult perch, other walleye, and the sauger prey on young walleye. Many fish-eating birds and mammals also take young walleye.
• The walleye's low-light vision and sensitivity to bright light play a large role in its behavior. They usually feed in shallow water at dawn and dusk. Walleye are fish-eaters, preying heavily on yellow perch, which cannot see as well as the walleye in low light and thus are easy prey at night.
• Yellow perch, sauger, and smallmouth bass are the walleye’s main competitors for food.

Immediately after the yolk sac is absorbed, the fry begins to feed. At first only the tiniest planktonic organisms can be utilized, but as the fish increase in size, cladocerans and immature aquatic insects are consumed. Small fry are sometimes observed in schools on the spawning grounds but soon disperse. After the fish reach approximately 2" in length, they begin to add small fishes, minnows, yellow perch, suckers, and bluegill to their diet. Adult walleye consume large quantities of fish, sometimes feeding upon them almost entirely. Yellow perch make up a substantial part of the walleye diet in the natural lakes. The next time you catch a walleye, or for that matter its first cousin a sauger, take a moment to carefully examine its eyes. Not only are these features the origin of its common name and a prominent part of their appearance, but their unique physiology permits this fish to adapt into an ecological niche that is occupied by few other species. Walleye are perfectly adapted for capturing prey in very low light, or even in total darkness. At the same time in most clear waters that they occupy, they forage most effectively at dawn and dusk when the prey fishes have limited vision but remain active. For this reason, walleye are termed low light condition feeders, and fishing success is traditionally best during these periods. Some of the most avid walleye fishermen never fish during daytime, finding catch success best in semi- or total darkness.
• The large, unusual eyes of the walleye are designed to help them easily find their prey.

In clear lakes the walleye often lie in contact with the bottom, seemingly resting. In these lakes, they usually feed from top to bottom at night. In more turbid water they are more active during the day, swimming slowly in schools close to the bottom.
• Walleye frequently are associated with other species such as yellow perch, northern pike, white suckers and smallmouth bass. White suckers, for example, orient themselves in walleye schools and behave as part of them. During the winter the walleye do not change their habitat except to avoid strong currents.

History:

• U.S. Record: 25lb, 0oz, from Old Hickory Lake, Tennessee, 8/1/60
• Minnesota Record: 17lb 8oz, from the Seagull River (Cook County).

Uses:

• One of the most important game fish in North America. Not a spectacular fighter when hooked, but quite tasty on the table. Second only to the Largemouth Bass (Micropterus salmoides) in popularity in the US, it reigns supreme in Canada.
• Taken commercially on the Great Lakes and in Canada. Probably the most economically valuable species of Canada's inland waters.

Reproduction:

• Begin moving toward spawning areas in streams and on lake bottoms in late winter and early spring. These are usually rocky areas in flowing water below impassible falls and dams in rivers and streams, coarse-gravel shoals, or along rubble shores of lakes at depths of less than 6'. Males move into spawning areas in early spring when the water temperature may be only a few degrees above freezing, the larger females arriving later. Spawning peaks at water temperatures of 42º-50º F.
• Spawns at night over rock, rubble, gravel and similar substrates in rivers or windswept shallows, 1'-6' deep, where current clears away fine sediment and will cleanse and aerate eggs. A 5 lb female deposits more than 100,000 eggs. Neither parent cares for the eggs in any way.
• Spawning success can vary greatly year to year, depending on weather. Rapidly warming water can cause eggs to hatch prematurely. Prolonged cool weather can delay and impair hatching. A cold snap after hatch can suppress production of microcrustaceans that fry eat. Year-class presence can vary 100-fold, depending on the success of the hatch and survival of the fry. One walleye year-class may dominate in a lake, while walleye a year older or a year younger are scarce.
• Individual eggs lodge in rubble or gravel crevices where they will be protected and where water can circulate, keeping them silt free and oxygenated. No protection is provided by the parents. Once spawning is completed, adults return to deep water.
• The number of eggs produced by individual females varies according to body size and physical condition, but normal fecundity ranges from 23,000 to 50,000 per pound of fish weight. Incubation lasts 12 to 18 days, depending upon water temperature. Under the best of conditions 5%-20% 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 which decrease hatching odds.
• Upon hatching, the newborn fry is about 1/2" long and paper thin. For several days it will drift about, absorbing the yolk sac and gaining strength.
• Eggs hatch in 12-18 days on the spawning grounds and by 10-15 days after hatching the young have dispersed into the upper levels of open water. By the latter part of the summer, young-ofthe-year move toward the bottom. Growth is fairly rapid in the south, but slower in more northerly latitudes. Females grow more quickly than males.
• The male walleye is not territorial, and does not build a nest. The fertilized eggs are heavier than the water and fall into crevices in the stream or lake bottom where they stick to stones and debris. The maximum number of eggs released by one female has been estimated at 612,000.
• The walleye is not a territorial fish at spawning time; they usually broadcast their eggs and exercise no parental care.
• But more important in controlling populations are water temperature, stream flow and wind at spawning time, and interference from other species which spawn over the walleye eggs. The major controlling factor of walleye populations appears to be mortality during the egg and fry stage.
• Males generally mature at two to four years of age and females at three to six years of age.

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Last updated on 13 November 1999