Animal Diversity Web

Ge­o­graphic Range

Walleyes are na­tive to fresh­wa­ter rivers and lakes of the north­ern United States and Canada. Their na­tive range makes a lop­sided tri­an­gle with the south­ern­most point on the Gulf of Mex­ico bor­der be­tween Mis­sis­sippi and Al­abama, ex­tend­ing up­wards (bound on both sides by the Ap­palachian and Rocky Moun­tains) to­wards the north­ern­most bor­der be­tween the provinces of Yukon and the North­west Ter­ri­to­ries, then back along the south­ern edge of the Hud­son Bay, peak­ing again at the At­lantic Coast, just north of Que­bec City. They stay safely in­land aside from river deltas and away from the salt wa­ters of the coast. Their range has ex­panded some­what over the years by in­tro­duc­ing them to var­i­ous parts of North Amer­i­can, es­pe­cially the United States, where they have greatly ex­panded their range via human means to in­clude large chunks of the North­east, from south­east Maine down to Vir­ginia, pass­ing lightly through North Car­olina to es­tab­lish a firm hold on in­land South Car­olina and Geor­gia. Their in­tro­duced range is equally vast in the west­ern United States, al­though much more spread out, and in­cludes large parts of nearly all the west­ern and south­west­ern states, branch­ing off very slightly into south­ern British Co­lum­bia. As a cool-wa­ter species, their nat­ural habi­tat is greatly skewed to­wards the north­ern United States and much of Canada. Their suc­cess in their in­tro­duced ranges likely de­pends in part on lat­i­tude and el­e­va­tion. Pre­dic­tions on the ef­fects of cli­mate change on wall­eye pop­u­la­tions sug­gest the more south­ern ranges will be­come less hab­it­able and the north­ern wall­eye pop­u­la­tions will be­come dom­i­nant. (Billing­ton, et al., 2011; Bozek, et al., 2011a)

• Biogeographic Regions
• nearctic
  • introduced
  • native

Habi­tat

Walleyes are be­lieved to have evolved in the North Amer­i­can river sys­tems, and moved only re­cently (in evo­lu­tion­ary terms) into lake en­vi­ron­ments. For this rea­son, many of the phys­i­cal re­quire­ments that char­ac­ter­ize op­ti­mal wall­eye habi­tat have qual­i­ties that closely re­sem­ble rivers, es­pe­cially those areas of rivers that form slow-mov­ing pools such as oxbows, sloughs, and em­bay­ment habi­tats. While walleyes live in both rivers and lakes in the mid­dle and north­ern end of their range, they live al­most ex­clu­sively in rivers far­ther south. Walleyes pre­fer shal­low to mod­er­ately deep lo­ca­tions with ex­ten­sive shal­low areas and shore­line. They live mainly in the lit­toral and sub­lit­toral lay­ers of lakes (al­though they make short, daily mi­gra­tions to the pelagic layer), mov­ing deeper into the sub­lit­toral lay­ers dur­ing the day­light hours in keep­ing with their noc­tur­nal lifestyles. These fish pre­fer murky water, with less than 2 me­ters of light pen­e­tra­tion. By day, walleyes rest on their pre­ferred sub­strate, sand and large gravel, with plenty of sub­merged veg­e­ta­tion in a mod­er­ate cur­rent. Walleyes tend to do well in large shal­low lakes with plenty of lit­toral and sub­lit­toral zones and min­i­mal sea­sonal strat­i­fi­ca­tion. These fish can still be found in many river sys­tems, but their pres­ence has de­clined in these habi­tats, likely due to the in­creased eu­troph­i­ca­tion of North Amer­i­can rivers. (Kitchell, et al., 1977)

As a cool water species, the cli­mate of a lo­ca­tion is im­por­tant to the well being of walleyes. The eggs have been shown to be par­tic­u­larly re­silient to fluc­tu­at­ing tem­per­a­tures, and are able to sur­vive rapid tem­per­a­ture changes of up to 20 to 21°C (68 to 70°F) in lab­o­ra­tory set­tings with no dis­cern­able in­crease in mor­tal­ity, al­though it did re­sult in an in­crease in ab­nor­mal fry. Tem­per­a­ture first af­fects wall­eye re­pro­duc­tion at the spawn­ing stage, with op­ti­mum egg fer­til­iza­tion tem­per­a­tures around 6 to 12°C (42 to 53°F), op­ti­mal egg in­cu­ba­tion tem­per­a­tures around 9 to 15°C (48 to 59°F), and the op­ti­mal hatch­ing tem­per­a­ture is around 15°C. Tem­per­a­ture af­fects growth rates by reg­u­lat­ing the me­tab­o­lism, food con­ver­sion abil­ity, and the abil­ity to se­cure food. Their pre­ferred tem­per­a­ture for max­i­mum growth is be­tween 20 to 24°C (68 to 75°F). This tem­per­a­ture may be higher for ju­ve­niles, to be­tween 27 to 31°C (80 to 88°F). As much as 21% of wall­eye re­cruit­ment is pos­i­tively cor­re­lated with spring water tem­per­a­tures, mak­ing tem­per­a­ture an ex­tremely im­por­tant fac­tor in early de­vel­op­ment and growth. Dis­solved Oxy­gen (DO) con­cen­tra­tions for wall­eye em­bryos is above 5 to 6 mg/L, al­though this num­ber is linked to tem­per­a­ture, since in­creased tem­per­a­ture can in­crease both meta­bolic func­tions in fish as well as de­crease the sol­u­bil­ity of oxy­gen. Walleyes do rel­a­tively well with DO fluc­tu­a­tions, they may sur­vive for ex­tended pe­ri­ods with only 3 mg/L of DO, and shorter pe­ri­ods with even less. How­ever, walleyes are more sen­si­tive than many other species of fish to­wards very high oxy­gen lev­els. They ex­pe­ri­enced a sud­den die off due to “Gas-Bub­ble Dis­ease” in a Wis­con­sin lake when the water be­came su­per­sat­u­rated with DO. Walleyes pre­fer pH lev­els be­tween 6.0 to 9.0. Lower, more acidic lev­els sub­stan­tially de­crease sur­vival and re­pro­duc­tive suc­cess. Due to their abil­ity to with­stand rel­a­tively low dis­solved oxy­gen lev­els, walleyes have been able to sur­vive under fairly harsh con­di­tions. How­ever, their eggs are more sus­cep­ti­ble to neg­a­tive en­vi­ron­men­tal con­di­tions. In ad­di­tion to sul­fides and am­mo­nia, re­search in­di­cates that cer­tain lev­els of heavy met­als and salin­ity can also af­fect wall­eye sur­vival, re­pro­duc­tion, and be­hav­ioral pat­terns. (Auer and Auer, 1990; Becker, 1983; Bozek, et al., 2011a; Has­nain, et al., 2010; Kitchell, et al., 1977; Maden­jian, et al., 1996; Pauley and Nakatani, 1967)

Walleyes sur­vival and re­pro­duc­tion, like most river­ine species, has been di­rectly im­pacted in many in­stances by the cre­ation of dams along their na­tive wa­ter­ways. Dams can dis­rupt their mi­gra­tions by ei­ther block­ing ac­cess to na­tive spawn­ing areas or by flood­ing these areas be­yond their use­ful­ness for spawn­ing. Un­like some species, how­ever, their re­ac­tions have been mixed. There are cer­tainly ex­am­ples of un­suit­able or con­t­a­m­i­nated reser­voirs pre­vent­ing suc­cess­ful wall­eye pop­u­la­tion num­bers, so long as all the con­di­tions for sur­vival and re­pro­duc­tion are pre­sent, walleyes have adapted very suc­cess­fully to life in reser­voirs, as well as ex­ten­sions of their range due to human in­tro­duc­tions. (Bozek, et al., 2011a)

• Habitat Regions
• temperate
• polar
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams

Phys­i­cal De­scrip­tion

Walleyes are rel­a­tively small for preda­tory fish, reach­ing an av­er­age adult size of 350mm among males and 450mm among fe­males. Walleyes are darkly col­ored on top, with col­ors rang­ing from brown, to olive, to dark yel­low with a paler un­der­side, rang­ing from white to pale yel­low. Walleyes have sil­very eyes that have a re­flec­tive un­der­layer, which causes it to re­flect in the dark. Their mouths con­tain a se­ries of very sharp teeth, spe­cial­ized for a pis­civ­o­rous lifestyle. Some sex­ual di­mor­phism ex­ists within this species in that fe­males grow con­sis­tently larger than males. (Becker, 1983; Bozek, et al., 2011b; Ohio De­part­ment of Nat­ural Re­sources, 2013)

• Other Physical Features
• ectothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

• Average mass

  11000 g

  387.67 oz

  AnAge

• Average length

  350-450 mm

  in

De­vel­op­ment

Like many fish, walleyes begin their de­vel­op­ment as an egg and progress into the lar­val and ju­ve­nile stages, be­fore be­com­ing an adult. In­di­vid­ual fe­male walleyes re­lease tens of thou­sands to hun­dreds of thou­sands of eggs dur­ing each spawn­ing pe­riod. These eggs are roughly 2mm in di­am­e­ter on av­er­age. The eggs begin their life cycle coated in an ad­he­sive for some­times sev­eral hours, which is be­lieved to in­crease the fer­til­iza­tion rate. Once fer­til­ized, the egg hard­ens, los­ing its ad­he­sive­ness and floats into safer pro­tec­tive sub­strate where, with proper pro­tec­tion, tem­per­a­ture, and oxy­gen, it even­tu­ally hatches. De­spite hatch­ing, lar­vae are still con­sid­ered em­bryos due to their un­der­de­vel­oped fins and fin rays. These begin to de­velop when the lar­vae reach ap­prox­i­mately 10mm in length (they range from 6 to 9mm at hatch­ing), with full os­si­fi­ca­tion at 18mm. Be­cause they are still un­der­de­vel­oped (which in­cludes an un­der­de­vel­oped swim blad­der, in­hibit­ing their buoy­ancy), the lar­vae con­tinue to sit on the sub­strate and are sub­ject to their lo­ca­tion’s cur­rent, being swept away (if the spawn­ing site was well cho­sen) into nurs­ery habi­tats. Due to the small size of the egg, lar­vae have very lit­tle yolk to con­sume upon hatch­ing and must begin feed­ing im­me­di­ately on var­i­ous zoo­plank­ton and chi­rono­mids. Prey den­sity can play a large role in sur­vival at this early stage, as does preda­tor den­sity, since both wall­eye eggs and lar­vae are com­mon sources of food for larger fish. In­deed, very few wall­eye make it to 1 year of age. Sur­vival rate es­ti­mates of lar­val wall­eye are in the order of 0.01%, due mainly to lack of fer­til­iza­tion of eggs, star­va­tion upon hatch­ing, and pre­da­tion. Upon sur­viv­ing their first year, how­ever, wall­eye growth is rapid. Both male and fe­male walleyes grow at the same rate prior to this time, but upon reach­ing the ju­ve­nile life stage, growth rates can begin to dif­fer, de­pend­ing on growth rates in a par­tic­u­lar lo­ca­tion. Walleyes in the south­ern part of their range, for in­stance, grow more quickly in gen­eral than walleyes in the north, with fe­male walleyes grow­ing larger than males. Be­cause adult­hood is de­ter­mined mostly by size, the ju­ve­nile stage can last any­where from two to eight years, de­pend­ing on ge­o­graphic lo­ca­tion and food avail­abil­ity. Av­er­age length at adult­hood (de­fined as reach­ing sex­ual ma­tu­rity) is con­sid­ered 350mm for males and 450mm for fe­males al­though this varies be­tween in­di­vid­u­als. As this size dif­fer­ence in­di­cates, males typ­i­cally reach sex­ual ma­tu­rity be­fore fe­males. (Bozek, et al., 2011b; Moore, 2011)

Re­pro­duc­tion

Walleyes are promis­cu­ous: fe­males and males spawn with mul­ti­ple part­ners with no in­di­ca­tion of last­ing re­la­tion­ships. Mat­ing takes place in a marsh­land. Male walleyes fre­quent the spawn­ing marsh­land for sev­eral weeks, how­ever, fe­male walleyes go only to spawn, which lasts ap­prox­i­mately one day. Nei­ther sex dis­plays ter­ri­to­r­ial be­hav­ior dur­ing this time. (Becker, 1983)

• Mating System
• polygynandrous (promiscuous)

Wall­eye spawn­ing oc­curs once an­nu­ally in early spring. Spawn­ing be­hav­ior is tem­per­a­ture de­pen­dent, with spawn­ing oc­cur­ring at 5°C (41°F). With the ex­ten­sive range of this species, the exact dates vary ac­cord­ing to cli­matic con­di­tions. Walleyes dis­play hom­ing be­hav­ior, re­turn­ing to the same site again and again to spawn. Fe­male and male walleyes reach sex­ual ma­tu­rity at dif­fer­ent ages and sizes. Fe­male walleyes ul­ti­mately re­lease tens of thou­sands to hun­dreds of thou­sands of eggs in a sin­gle spawn­ing ses­sion, which is it­self bro­ken up into ap­prox­i­mately five minute egg re­lease in­ter­vals for the du­ra­tion of spawn­ing. (Bar­ton and Barry, 2011; Becker, 1983; Bozek, et al., 2011b)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• fertilization
  • external
• broadcast (group) spawning
• oviparous

• Breeding interval

  Walleyes spawn once a year.

• Breeding season

  These fish spawn in early spring.

• Average number of offspring

  150000

  AnAge

• Range age at sexual or reproductive maturity (female)

  3 to 6 years

• Range age at sexual or reproductive maturity (male)

  2 to 4 years

There is no ev­i­dence of parental care of any kind tak­ing place among walleyes. (Becker, 1983)

• Parental Investment
• no parental involvement

Lifes­pan/Longevity

In­ter­est­ingly, the max­i­mum age and mor­tal­ity rate are strongly cor­re­lated with the growth rate of walleyes. Walleyes that grow big­ger faster tend to have shorter lifes­pans than walleyes that grow more slowly. While the max­i­mum lifes­pan of fast-grow­ing south­ern walleyes is 3 to 4 years, north­ern wall­eye have been known to live as long as 20 years, or pos­si­bly up to 30 years. Due to their enor­mous size and vari­abil­ity of their range, wall­eye mor­tal­ity rates are very dif­fi­cult to es­ti­mate, mak­ing av­er­ages and ranges nearly mean­ing­less. For ex­am­ple, nat­ural mor­tal­ity rates for lakes and rivers sam­pled in North Amer­ica range from 3 to 81%, an enor­mous dif­fer­ence which means lit­tle for wall­eye pop­u­la­tions in gen­eral. In ad­di­tion, walleyes are a pop­u­lar sport fish, mean­ing that mor­tal­ity rates must take into ac­count both nat­ural deaths and ex­ploita­tion num­bers. Total mor­tal­ity an­nual rates ranged from 13 to 84% across 14 dif­fer­ent lakes and rivers in North Amer­ica, most com­monly falling be­tween 40% and 55%. (Bozek, et al., 2011b; Nate, et al., 2011)

• Range lifespan
  Status: wild

  3 to 30 years

• Typical lifespan
  Status: wild

  3 to 30 years

Be­hav­ior

Once walleyes reach a cer­tain size (be­tween 51 and 100mm), they begin dis­play­ing more de­m­er­sal be­hav­ior, tend­ing to­wards deeper, cooler, darker depths dur­ing the day­light hours. This cor­re­sponds to cer­tain de­vel­op­men­tal mile­stones, in­clud­ing changes in the retina that allow walleyes to see more clearly in dim light. Walleyes are noc­tur­nal preda­tors with a high vi­sual acu­ity be­yond the abil­i­ties of many other vi­sual fish preda­tors, al­though they seem to have sac­ri­ficed lat­eral line sen­si­tiv­ity rel­a­tive to these other species in ex­change for the abil­ity. If ideal depths are not avail­able, walleyes have been known to seek out dense veg­e­ta­tion or other phys­i­cal cover dur­ing the day­light hours to re­duce their light ex­po­sure. Walleyes are more ac­tive at dusk and dawn. (Bozek, et al., 2011a)

• Key Behaviors
• natatorial
• nocturnal
• motile

Home Range

Wall­eye be­hav­ior tends to vary with age as well as lake ver­sus river lifestyles. Due to their lim­ited de­vel­op­ment upon hatch­ing, lar­val walleyes in rivers are found in all depths, from the sur­face to near the stream bot­tom, likely in­flu­enced more by cur­rent than any other con­sid­er­a­tions. In con­trast, lake wall­eye lar­vae tend to live a more pelagic lifestyle (stick­ing to deeper parts of the lake) al­though they, too, have been found in mul­ti­ple lo­ca­tions. As walleyes grow more de­vel­oped and as­sume more con­trol over their move­ment, they dis­play shoal­ing be­hav­ior with fish of their same size (though not al­ways of their same species). Walleyes do not show ter­ri­to­r­ial be­hav­ior, how­ever, these fish do seem to main­tain gen­eral home ranges when they are not in their spawn­ing grounds. These home ranges vary based on the in­di­vid­ual, as well as whether they in­habit a lake or river, in­di­vid­u­als in­hab­it­ing rivers typ­i­cally have a smaller home range size than those in lakes. Home range sizes do not ap­pear to vary based on gen­der. In one study, walleyes in the New River, Vir­ginia, main­tained a me­dian home range size of 4.7 km, al­though they moved fre­quently from week to week. (Becker, 1983; Bozek, et al., 2011a; Palmer, et al., 2005)

Com­mu­ni­ca­tion and Per­cep­tion

Al­though walleyes are a shoal­ing species, which means they move to­gether in a loose con­gre­ga­tion in open wa­ters, there is lit­tle ev­i­dence of ad­vanced com­mu­ni­ca­tion sys­tems be­tween mem­bers. Walleyes are not ter­ri­to­r­ial, nor do they keep mates or in­vest time in off­spring. The only ex­am­ple of ob­served com­mu­nica­tive move­ments by walleyes is dur­ing mat­ing, when male walleyes bump against the fe­males and, when she is ready to spawn, the fe­male sig­nals so by turn­ing on her side. (Becker, 1983)

• Communication Channels
• visual

• Perception Channels
• visual
• tactile
• chemical

Food Habits

While wall­eye eggs and lar­vae tend to be a fre­quent source of food for a large va­ri­ety of fishes, adult walleyes sit at the top of the food chain in many sys­tems. Walleyes be­come pis­civ­o­rous early in life, feed­ing on the lar­vae of other fish as soon as they get big enough. Adult walleyes feed on a large va­ri­ety of other fish species, in­clud­ing yel­low perch, giz­zard shads, emer­ald shin­ers, spot­tail shin­ers, and nu­mer­ous other species, de­pend­ing on what is avail­able in a given ecosys­tem. These fish have also been doc­u­mented con­sum­ing smaller con­specifics. In sit­u­a­tions in which fish species are not read­ily avail­able, walleyes may also eat cer­tain types of in­ver­te­brates. (Nate, et al., 2011)

• Primary Diet
• carnivore
  • piscivore
  • insectivore

• Animal Foods
• fish
• insects

Pre­da­tion

Walleyes are gen­er­ally top preda­tors in their habi­tat; how­ever, this high place in the food chain is not uni­ver­sal. Be­cause walleyes do not get overly large on av­er­age com­pared to other preda­tor species, they, too, can be­come prey in cer­tain eco­log­i­cal food­webs. Walleyes have fallen vic­tim to species such as large­mouth bass, small­mouth bass, muskel­lunges, yel­low perch, and other walleyes. Non-fish preda­tors such as cor­morants have also been known to eat subadult walleyes. In gen­eral, how­ever, walleyes usu­ally be­come prey in the early years of their de­vel­op­ment. Be­fore reach­ing adult sta­tus, wall­eye eggs, lar­vae, and ju­ve­niles can form a reg­u­lar food source for fish species of many sizes and va­ri­eties, in­clud­ing not only other pis­civ­o­rous fish such as white perch, stonecats, and white suck­ers, but also plank­ti­vores such as black crap­pies, white crap­pies, and alewives. In one Kansas reser­voir, white crap­pie pop­u­la­tion num­bers were in­versely cor­re­lated with wall­eye abun­dance, mean­ing this early pre­da­tion can have a very real ef­fect on the preda­tor’s longer term suc­cess. The enor­mous num­ber of eggs and lar­vae pro­duced by each fe­male, as well as the tem­per­a­ture re­quire­ments for spawn­ing, which is much colder than many fish species pre­fer, are both likely adap­ta­tions to egg and lar­val pre­da­tion. (Nate, et al., 2011; Quist, et al., 2003)

• Known Predators

  • Largemouth Bass Micropterus salmoides
  • Smallmouth Bass Micropterus dolomieu
  • Muskellunge Esox masquinongy
  • Yellow Perch Perca flavescens
  • White Perch Morone americana
  • Stonecat Noturus flavus
  • White Sucker Catostomus commersonii
  • Black Crappies Pomoxis nigromaculatus
  • White Crappies Pomoxis annularis
  • Alewife Alosa psuedoharengus
  • Cormorant: Family Phalacrocoracidae

Ecosys­tem Roles

As top preda­tors, walleyes have a pro­found role in the ecosys­tem, which is also mul­ti­fac­eted and com­plex. Like most preda­tor/prey re­la­tion­ships, the abun­dance of walleyes and their pre­ferred prey species are highly in­ter­re­lated. An in­crease in adult walleyes can lead to a de­crease in their prey. How­ever, de­spite adult walleyes being at the top of their food chain, their lar­vae, eggs, and some­times ju­ve­niles re­main near the bot­tom. For this rea­son, the preda­tor/prey re­la­tion­ship be­comes more dy­namic, as in­creases in species such as yel­low perch, can ad­versely af­fect wall­eye pop­u­la­tions as fewer and fewer lar­vae make it to adult sta­tus. Yel­low perch are the pre­ferred prey of adult walleyes in many cir­cum­stances. Since yel­low perch feed heav­ily on ju­ve­nile walleyes, a focus on yel­low perch as a prey species ac­tu­ally aids in ju­ve­nile sur­vival. This re­la­tion­ship ex­tends be­yond the sur­vival of these two species. It has, in some in­stances, dra­mat­i­cally in­creased the im­por­tance of the role that yel­low perch play in the ecosys­tem as a whole. If yel­low perch pop­u­la­tions begin to de­crease, walleyes must turn to other species for food (some­thing they do with lit­tle hes­i­ta­tion) caus­ing a rip­ple ef­fect across the ecosys­tem as prey from var­i­ous eco­log­i­cal niches begin to de­crease in num­bers. (Nate, et al., 2011)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Walleyes are one of the most pop­u­lar sports fishes in North Amer­ica. The species is prized by Cana­dian, Amer­i­can, and Na­tive Amer­i­can fish­eries alike and has a sub­stan­tial na­tional and in­ter­na­tional legal frame­work sur­round­ing their cap­ture. Fish­ing ranges from sub­sis­tence to recre­ational to com­mer­cial with mil­lions of kilo­grams har­vested an­nu­ally. Sur­pris­ingly, recre­ational fish­ing has proven the most lu­cra­tive in­vest­ment in wall­eye fish­ing. While Canada’s com­mer­cial wall­eye fish­eries on Lake Erie and var­i­ous other Cana­dian lakes total around CAN$60 mil­lion an­nu­ally, the wall­eye recre­ational fish­ing in­dus­try in Lake Erie alone total around $600 mil­lion an­nu­ally. Due to their ex­ten­sive range, wall­eye fish­ing is pop­u­lar through­out the United States and Canada. In ad­di­tion to lake and river pop­u­la­tions, walleyes also con­sti­tute the base of a thriv­ing aqua­cul­ture busi­ness, a prac­tice used pri­mar­ily for stock­ing, rather than as a food provider. (Bozek, et al., 2011a; Schmalz, et al., 2011)

• Positive Impacts
• food
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive ef­fects of walleyes on hu­mans.

Con­ser­va­tion Sta­tus

Due to their im­mense pop­u­lar­ity, walleyes are the sub­ject of in­tense scrutiny and study. Man­age­ment sys­tems of wall­eye stocks range from sim­ple to ex­tremely com­plex, usu­ally op­er­at­ing under the as­sump­tion that stock ex­ploita­tion plays a lead­ing role in fish pop­u­la­tions (as op­posed to other fac­tors, such as habi­tat and food avail­abil­ity) and man­ages ac­cord­ingly. These reg­u­la­tions are most reg­u­larly in the form of bag or length lim­its. There is ev­i­dence that these ef­forts can and have been ef­fec­tive in help­ing over­ex­ploited wall­eye pop­u­la­tions to re­cover. A po­ten­tial wall­eye sub­species, blue pike, were once en­demic to Lake Erie and Lake On­tario, but are now be­lieved to be ex­tinct. Blue pike were smaller than walleyes and pre­ferred to in­habit greater depths than walleyes. Al­though no blue pike are now known to exist, tis­sue stud­ies show no dis­cernible ge­netic dif­fer­ence be­tween the species. Blue pike might have been a sym­patric morph or species pair with walleyes. If this were the case, an­thro­pogenic habi­tat changes could have lead to blue pike and wall­eye habi­tat crossover, caus­ing blue pike to be ge­net­i­cally mixed back into the wall­eye gene pool. An­other ge­netic quirk of walleyes is their abil­ity to hy­bridize with saugers to form a fish known as a "saug­eye". This hy­bridiza­tion can occur nat­u­rally, al­though this is rare, as their mat­ing sea­sons rarely over­lap. This mix is bred ar­ti­fi­cially as a stock species, as saugeyes tol­er­ate warmer, more eu­trophic wa­ters than walleyes and have a faster growth rate than both species. The hy­brid's abil­ity to breed with saugers and walleyes may have the po­ten­tial to break down the ge­netic bar­rier be­tween the species should they be pre­sent in large enough num­bers in the same area. It has been ar­gued that even stock­ing saugeyes in lakes sep­a­rate from both species has the po­ten­tial to con­t­a­m­i­nate this ge­netic line, as high rains and flood­ing could re­sult in a mix­ing of the species. (Billing­ton, et al., 2011; Schmalz, et al., 2011)

• IUCN Red List

  Least Concern

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Other Com­ments

There has been some de­bate as to the ap­pro­pri­ate tax­on­omy of walleyes. Since the early 1800’s, walleyes were known as Sander vit­reus and their tax­o­nomic move­ment to Sander vit­reus is a re­cent change. The In­ter­na­tional Com­mis­sion of Zo­o­log­i­cal Nomen­cla­ture has de­clared Sander vit­reus the of­fi­cial sci­en­tific name of the species, al­though the de­bate con­tin­ues, with some sci­en­tists claim­ing that the com­mis­sion’s rules were not cor­rectly fol­lowed when the name was es­tab­lished. Searches for re­search on walleyes re­veal a great deal of re­search listed under both names. (Bruner, 2011)

Con­trib­u­tors

Betsy Riley (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Jeff Scha­ef­fer (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, Lau­ren Sal­lan (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, Leila Si­cil­iano Mar­tina (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Ref­er­ences

United States En­vi­ron­men­tal Pro­tec­tion Agency. Spa­tial Dis­tri­b­u­tion and Tem­per­a­ture Se­lec­tion of Fish near the Ther­mal Out­fall of a Power Plant dur­ing Fall, Win­ter and Spring. 600/3-80-008. Du­luth, MN: Uni­ver­sity of Min­nesota. 1980.

Auer, N., M. Auer. 1990. Chem­i­cal Suit­abil­ity of Sub­strates for Wall­eye Egg De­vel­op­ment in the Lower Fox River, Wis­con­sin. Trans­ac­tions of the Amer­i­can Fish­eries So­ci­ety, 119:5: 871-876.

Bar­ton, B., T. Barry. 2011. Re­pro­duc­tion and En­vi­ron­men­tal Bi­ol­ogy. Pp. 1-34 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.

Becker, G. 1983. Fishes of Wis­con­sin. Madi­son, WI: Uni­ver­sity of Wis­con­sin Press. Ac­cessed Oc­to­ber 09, 2013 at http://​digital.​library.​wisc.​edu/​1711.​dl/​EcoNatRes.​FishesWI.

Billing­ton, N., C. Wil­son, B. Sloss. 2011. Dis­tri­b­u­tion and Pop­u­la­tion Ge­net­ics of Wall­eye and Sauger. Pp. 1-28 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.

Bozek, M., D. Bac­cante, N. Lester. 2011. Wall­eye and Sauger Life His­tory. Pp. 1-70 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.

Bozek, M., T. Hax­ton, J. Raabe. 2011. Wall­eye and Sauger Habi­tat. Pp. 133-197 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.

Bruner, J. 2011. A Phy­lo­ge­netic Analy­sis of Per­ci­dae Using Os­te­ol­ogy. Pp. 1-80 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.

Has­nain, S., C. Minns, B. Shuter. 2010. Key Eco­log­i­cal Tem­per­a­ture Met­rics for Cana­dian Fresh­wa­ter Fishes. Cli­mate Change Re­search Re­port, 17: 1-51.

Kitchell, J., M. John­son, C. Minns, K. Lof­tus, L. Greig, C. Olver. 1977. Per­cid Habi­tat: The River Anal­ogy. Jour­nal of the Fish­eries Re­search Board of Canada, 34: 1936-1940.

Maden­jian, C., J. Tyson, R. Knight, M. Ker­sh­ner, M. Hansen. 1996. First-year Growth, Re­cruit­ment, and Ma­tu­rity of Walleyes in West­ern Lake Erie. Trans­ac­tions of the Amer­i­can Fish­eries So­ci­ety, 125: 821-830.

Moore, A. 2011. Ma­nip­u­la­tion of Fer­til­iza­tion Pro­ce­dures to Im­prove Hatch­ery Wall­eye Egg Fer­til­ity and Sur­vival. North Amer­i­can Jour­nal of Aqua­cul­ture, 65:1: 56-59.

Nate, N., M. Hansen, L. Rud­stam, R. Knight, S. New­man. 2011. Pop­u­la­tion and Com­mu­nity Dy­nam­ics of Wall­eye. Pp. 1-56 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.

Ohio De­part­ment of Nat­ural Re­sources, 2013. "A to Z Species Guide: Fish: Wall­eye." (On-line). ODNR Di­vi­sion of Wildlife. Ac­cessed Oc­to­ber 09, 2013 at http://​www.​dnr.​state.​oh.​us/​tabid/​6781/​Default.​aspx.

Palmer, G., B. Mur­phy, E. Haller­man. 2005. Move­ments of Walleyes in Clay­tor Lake and the Upper New River, Vir­ginia, In­di­cate Dis­tinct Lake and River Pop­u­la­tions. North Amer­i­can Jour­nal of Fish­eries Man­age­ment, 25: 1448-1455.

Pauley, G., R. Nakatani. 1967. Histopathol­ogy of 'Gas-Bub­ble" Dis­ease in Salmon Fin­ger­lings. Jour­nal of the Fish­eries Re­search Board of Canada, 24(4): 867-871.

Quist, M., C. Guy, J. Stephen. 2003. Re­cruit­ment dy­nam­ics of walleyes (Sander vit­reus) in Kansas reser­voirs: gen­er­al­i­ties with nat­ural sys­tems and ef­fects of a cen­trar­chid preda­tor. Cana­dian Jour­nal of Fish­eries and Aquatic Sci­ences, 60: 830-839.

Schmalz, P., A. Fayram, D. Is­er­mann, S. New­man. 2011. Har­vest and Ex­ploita­tion. Pp. 1-28 in B Bar­ton, ed. Bi­ol­ogy, Man­age­ment, and Cul­ture of Wall­eye and Sauger. Bethesda, MD: Amer­i­can Fish­eries So­ci­ety.