The Walleye (Sander vitreus vitreus, formerly Stizostedion vitreum vitreum) is a freshwater perciform fish native to most of Canada and to the northern United States. It is a North American close relative of the European pikeperch. However it should be noted that the walleye belongs to a family distinct from that of the perch. Walleye tend to be larger in size than perch and can distinguished from perch by their scale color. Furthermore, the walleye is sometimes also called the yellow walleye to distinguish it from the extinct blue walleye. In some parts of its range, the fish is known as the yellow pike or pickerel, although the use of these names should be discouraged since the fish is related neither to the pikes nor to the pickerels, both of which are members of the family Esocidae.
Genetically, walleyes show a fair amount of variation across watersheds. In general, fish within a watershed are quite similar and are genetically distinct from those of nearby watersheds. The species has been artificially propagated for over a century and has been planted on top of existing populations or introduced into waters naturally devoid of the species, sometimes reducing the overall genetic distinctiveness of populations.
Walleyes grow to about 75 cm (30 in) in length, and weigh up to about 7 kg (15 lb). The maximum recorded size for the fish is 107 cm (42 in) in length and 11.3 kg (25 lb) in weight. The growth rate depends partly on where in their range they occur, with southern populations often growing faster and larger. In general, females grow larger than males. Walleyes may live for decades; the maximum recorded age is 29 years. In heavily fished populations, however, few walleye older than 5 or 6 years of age are encountered.
Walleyes are largely olive and gold in colour (hence the French common name: dor - golden). The dorsal side of a walleye is olive, grading into a golden hue on the flanks. The olive/gold pattern is broken up by five darker saddles that extend to the upper sides. The colour shades to white on the belly. The mouth of a walleye is large and is armed with many sharp teeth. The first dorsal and anal fins are spinous as is the operculum. Walleyes are distinguished from their close cousin the sauger by the white colouration on the lower lobe of the tail.
The walleye is often considered to have the best tasting flesh of any freshwater fish, and, consequently, is fished recreationally and commercially. Because of its nocturnal feeding habits, it is most easily caught at night using live minnows or lures that mimic small fishes. Most commercial fisheries for walleye occur in the Canadian waters of the Great Lakes but there are other locations as well.
Because walleyes are popular with anglers, fishing for walleyes is regulated by most natural resource agencies. Management may include the use of quotas and length limits to ensure that populations are not over-exploited.