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Walleye (Sander vitreus, formerly Stizostedion vitreum) is a freshwater perciform fish native to most of Canadamarker and to the northern United Statesmarker. It is a North American close relative of the European pikeperch. The walleye is sometimes also called the yellow walleye to distinguish it from the Blue walleye, which is now extinct in the Great Lakes and critically endangered elsewhere.

In some parts of its range, the walleye is also mistakenly known as the colored pike, yellow pike or pickerel (esp. in English-speaking Canada), although the fish is related neither to the pikes nor to the other 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.

Meaning of the name

The common name, "walleye," comes from the fact that their eyes, like those of cats, reflect light. This eyeshine is the result of a light-gathering layer in the eyes called the tapetum lucidum which allows the fish to see well in low-light conditions. In fact, many anglers look for walleyes at night since this is when most major feeding patterns occur. Their eyes also allow them to see well in turbid waters (stained or rough, breaking waters) which gives them an advantage over their prey. Thus, walleye anglers will commonly look for days and locations where there is a good "walleye chop" (i.e., rough water). This excellent vision also allows the fish to populate the deeper regions in a lake and they can often be found in deeper water, particularly during the warmest part of the summer.

Physical description

Walleye, Sander vitreus
Walleyes are largely olive and gold in colour (hence the French common name: doré—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 caudal fin which is absent on the sauger. In addition, the two dorsals and the caudal fin of the sauger are marked with distinctive rows of black dots which are absent from or indistinct on the same fins of walleyes.

Length and Weight

Walleyes grow to about in length, and weigh up to about . The maximum recorded size for the fish is in length and 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. In North America, where they are heavily prized, their typical size when caught is on the order of 18-25 inches, substantially below their potential size.

As walleye grow longer, they increase in weight. The relationship between length and weight is not linear. The relationship between total length (L, in inches) and total weight (W, in pounds) for nearly all species of fish can be expressed by an equation of the form:
W = cL^b\!\,


Invariably, b is close to 3.0 for all species, and c is a constant that varies among species. For walleye, b = 3.180 and c = 0.000228.

The relationship described in this section suggests that a 20-inch walleye will weigh about 3 pounds, while a 25-inch walleye will likely weigh at least 6 pounds.

Reproduction

In most of the species' range, the majority of male walleyes have 3 testicles and mature at age 3 or 4. Females normally mature about a year later. Adults migrate to tributary streams in late winter or early spring to lay eggs over gravel and rock, although there are open water reef or shoal spawning strains as well. Some populations are known to spawn on sand or on vegetation. Spawning occurs at water temperatures of . A large female can lay up to 500,000 eggs and no care is given by the parents to the eggs or fry. The eggs are slightly adhesive and fall into spaces between rocks. The incubation period for the embryos is temperature-dependent but generally lasts from 12 to 30 days. After hatching, the free-swimming embryo spends about a week absorbing the relatively small amount of yolk. Once the yolk has been fully absorbed, the young walleye begins to feed on invertebrates such as fly larvæ and zooplankton. After 40 to 60 days, juvenile walleyes become piscivorous. Thenceforth, both juvenile and adult walleyes eat fish almost exclusively, frequently yellow perch or ciscoes, moving onto bars and shoals at night to feed. Walleye also feed heavily on crayfish, minnows, leeches, and earthworms.

As food

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 fish. Most commercial fisheries for walleye are situated in the Canadian waters of the Great Lakesmarker, but there are other locations as well.

Fishing

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. As one example, in the state of Michiganmarker, walleye of under 15" may not be legally kept, except in Lake St. Clair and the St. Clair River where fish of 13" may be legally taken.

Since walleyes have excellent visual acuity under low illumination levels, they tend to feed more extensively at dawn and dusk, on cloudy or overcast days and under choppy conditions when light penetration into the water column is disrupted. Although anglers interpret this as light avoidance, it is merely an expression of the walleye's competitive advantage over its prey under those conditions. Similarly, in darkly stained or turbid waters, walleye tend to feed throughout the day.

"Walleye chop" is a term used by walleye anglers for rough water typically with winds of , and is one of the indicators for good walleye fishing due to the walleye's increased feeding activity during such conditions.

Minnesota



The walleye is the state fish of Minnesotamarker and South Dakota. Its popularity with Minnesota residents means that the residents of that state consume more of the fish than in any other jurisdiction.

In 2004, it was revealed that some restaurants in the Minneapolis-St. Paulmarker region had been substituting the less expensive, imported zander for the walleye indicated on the menu. Zander (pikeperch) is a closely-related species and is almost impossible to tell apart by taste, so the television station that did the exposé had to send samples of food for DNA testing. Though sold as "walleye," several samples were found to be zander, which is considered an illegal practice by the U.S. Food and Drug Administration. Zander is native to the Danube Basin and rivers in southern Russiamarker.

Saskatchewan

On January 4, 2005 Father Mariusz Zajac from Carrot River caught a 18.30 lbs. Walleye while ice fishing. This walleye stands as the world record for ice fishing and had a girth of 22.5 inches and measured 36.5 inches in length.

In 2008 the government of Saskatchewanmarker declared the Walleye to be the province's official fish.

References



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