Walleye (Stizostedion vitreum)
Lake Ontario    (Fertilized Egg)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
711             Bay of Quinte   Pred/Prey         Example                  ­               9                       111

Details
­ High predation on walleye eggs by white bass was observed in the Bay of
  Quinte, Lake Ontario. 
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Erie       (Fertilized Egg)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
642             -               Temperature     Example             ­               473                     111

Details
­ In years of good-to-excellent year­class success in Lake Erie, the rate
  of water warming during the spawning and incubation periods was steady
  and rapid (>0.28°C/day) while in years of poorest year­class success,
  the rates of water warming were low. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
710             ­                Pred/Prey        Example               -               492                     111

Details
­ Stomachs of yellow perch, spottail shiners, stonecats, and white suckers
  contained walleye eggs in Lake Erie. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1549            ­                 Temperature     Optimum                  ­                1068                    1066

Details  
­ Steady spring warming rates of ³0.28°C/day have been positively correlated
  with embryo and fry production. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1550            ­               Temperature     Limit                     ­                1068                    1066

Details
- Poor survival of embryos is associated with cold water temperatures due to
  slow, spring warming rates (<0.18°C/day).
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1551            -               Temperature     Limit                       ­                         1068                    1066

Details
­ Poor survival of embryos is associated with cold weather fronts.
                                                                                                                                                             

Walleye (Stizostedion vitreum)
        (Fertilized Egg)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
586             ­                Depth         Characteristic  ­               111

Details
­ Walleye eggs are deposited in relatively shallow waters varying in depth from
  a few centimeters to several m. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
632             Minnesota                 Hydrogen        Example                 -               437                     111
                                   Sulphide
                                Oxygen   Example                 ­  
                                Wood Fiber      Example                  ­
                                Phys. Assoc.    Example                 ­

Details
­ Oxygen concentrations drop to low levels near the mud and water interface.
  Hydrogen sulphide concentrations are high over wood-fiber sludge deposits
  and are inimical to walleye eggs. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
635             Minnesota                 Phys. Assoc.    Example                 ­               464                     111

Details
­ Survival of eggs was poorest on soft muck detritus bottom, intermediate
  on fine sand bottom, and best on gravel rubble bottom.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
636             ­               Temperature      Example                 -               471                     111

Details
­ Incubation periods were:  33 days at 4.5°C, 10 days at 12.8°C and 14.4°C,
  8 days at 16.1°C, 8.5 days at 17.8°C, 6 days at 19.4°C, 5 days at 21.7°C,
  and 4 days at 23.9°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
637             Genoa, Wisconsin        Temperature     Optimum             17.8°­19.5°C    471                     111
                  (Hatchery)

Details
­ Experiments at the Genoa, Wisconsin, hatchery indicated that at constant 
  incubation temperatures, the optimum range for survival of walleye eggs is 
  17.8°­19.5°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
638             Genoa, Wisconsin        Temperature     Optimum         ­               1104                    111
                  (Hatchery)                                                                     450

Details
­ Optimum temperatures were 6°­12°C for fertilization and 9°­15°C for incubation. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
639             ­                          Water Level      Lethal               ­               487                     111

Details
­ Eggs spawned in shallow marshes often are left stranded above the water 
  level during times of low water.  High winds have also been known to blow
  significant numbers of eggs onto shore.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
707             ­                         Water Motion    Lethal                  -               111                     -

Details
­ Wave action may cause considerable egg mortality by washing viable eggs
  up on shore, or by moving them onto poor substrates where survival is
  reduced.  Wind is important in generating adequate circulation of oxygenated
  waters in and around incubating eggs.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.  708          ­               Water Level      Lethal             -               487                     111

Details  
­ Rainfall may be a critical survival factor in lakes where spawning beds
  are in very shallow water or in shallow marshes.  Eggs may be left dry
  when water levels recede or stagnation of the water may result in reducing
  the oxygen exchange rates to critical levels. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No. 
709             ­                  Pred/Prey       Example              -               111                     -

Details
­ Yellow perch, carp, suckers, minnows, bullheads, and yellow bass have been
  known to eat walleye eggs.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No. 
712             ­               Pred/Prey       Example             ­                   111                     -

Details
­ Northern pike, saugers, bullheads, burbot and yellow bass have been
  known to feed on walleye YOY.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1536            Minnesota               Phys. Assoc.     Optimum                   ­               464                     1066

Details
­ Highest embryo production and survival has been observed on clean gravel
  or rubble substrate (2.5-15.0 cm diam.). 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1537            Wisconsin               Phys. Assoc.     Example                 ­               487                     1066

Details
­ Survival is good on dense mats of vegetation with adequate water circulation. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1538            Minnesota                 Phys. Assoc.    Lethal                  -               464                     1066
                                                                                        487
Details
­ The survival percent of embryos is greatly reduced on sand.  Survival of eggs
  deposited on soft muck and detritus is negligible. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1539            ­                       Water Level     Optimum                  ­               464                     1066
                                                                                        1078
Details                                                                         475
­ Years of highest embryo production in lakes are associated with rising
  or stable spring water levels that increase the amount of littoral area 
  available for spawning and prevent stranding of embryos.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1540            ­                   Oxygen       Requirement     ³5 mg/l         1094                    1066

Details
­ DO levels ³5 mg/l are considered necessary for high survival and growth. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1541            Minnesota                  Oxygen     Limit                   £3.4 mg/l       437                     1066

Details
­ DO levels £3.4 mg/l resulted in delayed hatching and significant
  reduction in size at hatching.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1542            ­               Water Motion    Optimum             ­               866                     1066
                                                                                        462
Details
­ Positive correlations between spring river discharge and walleye year-class
  strength have been reported for several rivers. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1546            ­                       Temperature      Optimum            -               450                     1066

Details
- Optimum temperatures are 6°-9°C for fertilization and 9°-15°C for
  incubation. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1547            ­                         Temperature      Lethal                  ~19°C           1104                    1066

Details
­ Upper lethal (TL50) temperatures for embryos are ~19°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1548            ­                     Temperature     Example                    ­               1093                    1066

Details
­ Eggs hatch in 14-21 days at temperatures 8°-15°C. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1552            ­                Temperature      Limit                    ­               1095                    1066

Details
­ Poor survival of embryos is associated with the release of cold reservoir water 
  into tailwaters during spawning and incubation. 
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Erie       (Juvenile)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
676             ­                   Pred/Prey         Example                  ­                 493                     111

Details
- YOY walleye at the extreme western end of Lake Erie displayed their size
  preference by consuming alewives and gizzard shad during the summer and
  changing to rainbow smelt in the autumn (when alewives and shad became
  too large).
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
683             ­                Movement           Example                 ­               445                     111

Details
­ Tagging studies indicated that adults and juveniles from the Thames River
  (Lake St. Clair) stock moved in opposite directions during periods of
  migration.  Through late spring and summer, adults moved north from their
  spawning grounds on the Thames  River in the St. Clair River and southern
  Lake Huron, while juveniles moved south through the Detroit River into the 
  western basin of Lake Erie.  Through autumn, winter, and early spring these
  migrations were reversed.  Similar migration patterns were observed in Lake Erie.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
754             ­                    Pred/Prey       Example                    ­               529                     112

Details
­ 0+ walleye fed primarily on 0+ perch in Lake Erie until July when surviving
  perch grew out of the length range of fry preferred by walleye.  In June,
  they made up to 93% of identifiable food in walleye stomachs.  By September
  or October, they were reaching the size preferred by 1+ walleye.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
756             ­                Pred/Prey        Example             ­               73                      112
                                Oxygen   Example                   -

Details
­ In the case of the central basin of Lake Erie, perch and smelt fry are 
  protected from walleye predation due to hypolimnial oxygen depletion
  which excludes the walleye from their foraging base. 
                                                                                                                                                              Ref. No.      Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
795             ­               Pred/Prey          Example                   ­               73                      19

Details
­ Dominant year-classes of yellow perch can exert (three years after hatching)
  a predatory pressure on YOY walleye that forces walleye abundance into a
  three­year cycle.

Walleye (Stizostedion vitreum)
Lake Huron      (Juvenile)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
683             ­                    Movement         Example               ­               445                     111

Details
­ Tagging studies indicated that adults and juveniles from the Thames River
  (Lake St. Clair) stock moved in opposite directions during periods of
  migration.  Through late spring and summer, adults moved north from their
  spawning grounds on the Thames River in the St. Clair River and southern 
  Lake Huron, while juveniles moved south through the Detroit River into the
  western basin of Lake Erie.  Through  autumn, winter, and early spring these
  migrations were reversed.  Similar migration patterns were observed in Lake Erie.
                                                                                                                                                             

Walleye (Stizostedion vitreum)
        (Juvenile)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
588             ­                       Movement          Characteristic  ­               111                     -
                                Area of Water   Characteristic  ­

Details
­ At 25­30 mm long, fry become benthic and move back inshore.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
589             -               Movement            Characteristic  ­               111                     -
                                Depth       Characteristic  ­

Details
­ As summer progresses all age groups move to deeper waters.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
590             Minnesota                  Movement            Characteristic  -               465                     111     
                                Area of Water   Characteristic  -               481

Details
­ Adults and sub­adults moved back inshore in early autumn.  
                                                                                                                                                              Ref. No.      Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
591             ­                Movement        Characteristic  ­               111                     -
                                Depth     Characteristic  ­

Details
­ By late autumn and through winter all age groups moved into deeper waters.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
621             ­                     Pred/Prey       Optimum             ­               111                     -

Details
­ Lakes lacking suitable forage fishes maintain low stocks of walleye.
  Highest-standing stocks occur in lakes with abundant small percids,
  cyprinids, osmerids, percopsids, or coregonines.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
646             ­                             Pred/Prey            Characteristic  ­                 111                     -

Details
­ A number of fish species feed on walleye fry.  These include yellow perch,
  white bass, yellow bass, smallmouth bass, rainbow smelt, saugers, bullheads,
  burbot, and (most importantly) northern pike.                                              
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
650             ­                        Temperature      Optimum                 22°C              1104                    111
                                                                                        450
Details                                                                         449
- The optimum temperature for growth of juveniles (65.0­86.5 mm) is 22°C,
  but the range may include 19­25°C. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
651             ­                 Pred/Prey          Characteristic  ­                   111                     -

Details
­ During adolescence, walleyes change from a predominantly insect and
  crustacean diet to one consisting mainly of fishes (unless these are
  scarce).  During this period, diet and feeding habits are essentially
  the same as those of adults. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
654             Minnesota              Oxygen     Limit                      <5 ppm          486                     111
                (Hatchery)

Details
­ Oxygen concentrations <5 ppm result in poor survival of stocked walleye fry
  in Lake Traverse, Minnesota.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
655             ­                 Wood Fiber      Limit                       ­               436                     111
                                Temperature      Example                   ­
                                Oxygen       Example              ­

Details
­ Conifer and groundwater fiber at concentrations 50-150 ppm act as a loading
  and limiting stress, and reduced the scope for activity of walleye fingerlings.
  Under added environmental stresses (high temperature or low DO) these results
  suggest that suspended fiber loaded may decrease survival rates or reduce fish
  production in natural habitats. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
656             -               Hydrogen         Tolerate                        0.018­0.020 ppm 460                     111
                                   Sulphide

Details
­ The 96­hour median tolerance limit of H2S was 0.018­0.020 ppm. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
670             ­                   Pred/Prey           Limit                   ­               1104                    111
                                Temperature     Limit                   <15°C                 

Details
- Laboratory studies indicate that walleye fry feed infrequently at water
  temperatures <15°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
672             ­                Pred/Prey          Characteristic  ­               111                     -

Details
­ Adult and juvenile walleye are largely piscivorous and feed on a large
  variety of prey fishes.  In many lakes, invertebrates form a large part of
  the diet in late spring and early summer.  Invertebrate food is gradually 
  displaced by a diet consisting mainly of fish later in the summer when
  most of immature insect forms have metamorphosed and YOY prey fish are
  pelagic and readily available.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
673             ­                          Pred/Prey         Example                  ­               111                     -

Details
­ In many lakes in the northern and central regions of walleye distribution,
  YOY perch (when available) are the predominant prey fish.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
677             ­                      Temperature     Optimum                  19°­25°C        461                     111
                                                                                        1104
Details
­ The temperature range for optimum growth of juvenile walleye (84.2­
  86.5 mm long) is 19°-25°C. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
690             Minnesota               Movement            Example                  ­               465                     111
                                Depth          Example              ­

Details
­ Adults (age 2) were observed in Little Cutfoot Sioux Lake, Minnesota, to
  move from depths from 1.2­3.0 m to 3.7­4.3 m during mid­August.  Juveniles
  (age 1 and age 2) moved little during this time suggesting a differential
  movement by size or year­class.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
691             ­                Movement         Example                 ­               461                     111
                                Depth        Example                   ­               483
                                Temperature       Avoid                    ­

Details
­ YOY also moved from shore to deeper waters during midsummer to early autumn. These
  summer movements may be an avoidance reaction in response to rising temperatures.
                                                                                                                                                             

                                                                                                                                                              Ref. No.      Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
692             ­                         Movement          Characteristic  Schooling       111                     -

Details
­ Yearlings, sub­adults, and adults are usually closely similar in movement
  and schooling.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
693             ­                Movement            Characteristic  Schooling       439                     111

Details
- Yearlings, sub­adults, and adults have schooled together.  Underwater observations
  revealed the size of schools may range from 3-4 to several hundred or more fish.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
694             Minnesota            Movement          Characteristic  Schooling        474                     111
                                                                                        537
Details                                                                         465
­ YOY walleye show stronger schooling tendencies and are often associated
  with schools of YOY perch.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
702             ­                Light              Characteristic  Phototaxis      439                     111
                                                                                        457
Details
­ At precisely what time walleye become negatively phototaxic is not known.
  By age 1, walleyes are negatively phototaxic.
                                                                                                                                                              Ref. No.      Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
712             ­                Pred/Prey           Example                   ­               111                     -

Details
­ Northern pike, saugers, bullheads, burbot, and yellow bass have fed on
  walleye YOY.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
713             ­                  Pred/Prey         Lethal                  Cannabalism     111                     -

Details
­ Cannabalism is one of the most important sources of predation.  In some
  situations among fry, it may be the principal mortality factor.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
757             ­                   Pred/Prey           Example                  ­               503                     112
                                                                                        498
Details                                                                         513
­ Parallel fluctuations in year­class strengths of perch and walleye have been
  recorded in many American lakes.   
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
758             -               Pred/Prey       Example             ­               498                     112

Details
- The density of young perch fluctuated the same as growth increments of walleye.
  Therefore, walleye depended on young perch.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1509            ­                     Pred/Prey         Characteristic  -               1096                    1066
                                                                                        121
Details                                                                         1083
­ The diet of juvenile and adult walleye consists primarily of fish.
  Aquatic invertebrates (particularly mayfly larvae and crayfish) may be 
  locally or seasonally important.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1510            ­               Pred/Prey           Characteristic  ­               1077                    1066
                                                                                        857
Details
­ In northern areas, age O+ and 1+ yellow perch account for a large 
  portion of the diet in classic large, shallow perch­walleye lakes. 
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Erie       (Larva)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
642             ­                         Temperature     Example               ­               473                     111

Details
­ In years of good-to-excellent year­class success in Lake Erie, the rate of
  water warming during the spawning and incubation periods was steady and 
  rapid (>0.28°C/day) while in years of poorest year­class success, the
  rates of water warming were low.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
647             ­                         Competitors      Example                 ­               73                      111

Details
­ Rainbow smelt are implicated as serious competitors with walleye fry
  for food items in Lake Erie. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1549            ­                       Temperature      Optimum                   ­               1068                    1066

Details
­ Steady spring warming rates ³0.28°C/day have been positively correlated
  with embryo and fry production. 
                                                                                                                                                             

Walleye (Stizostedion vitreum)
        (Larva)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
587             -               Movement             Characteristic  ­               111                     -

Details
­ Upon hatching, fry leave spawning beds within a few hours and are carried
  by currents into limnetic waters.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
640             ­               Oxygen     Limit                      3.4 ppm         490                     111

Details
­ Larval size at hatching is reduced at 35% saturation levels of DO 3.4 ppm
  or less (flow rate 60 ml/min).
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
641             ­                       Oxygen        Limit                      ­               490                     111
                                Movement          Limit                    ­

Details
­ Larvae raised at 20% DO (1.9 ppm) and 25% DO (2.4 ppm) were noticeably
  weak swimmers.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
643             ­                Temperature      Optimum              15°­21°C          1104                    111

Details
­ The optimum temperature range for fry survival was 15°­21°C (test range
  6°­21°C).
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
644             ­                   Oxygen    Optimum                 4.8 ppm         490                     111
                                Temperature     Example                 17°C 

Details
- Optimum oxygen concentrations occur at 50% saturation (4.8 ppm at 17°C, flow
  rate 60 ml/min).                                   
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
645             ­               Pred/Prey          Example                 Daphnia              454                     111
                                                                                        453
Details
- There is some evidence of a positive correlation between Daphnia 
  abundance and fry survival.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
646             ­                       Pred/Prey         Characteristic   ­               111                     -

Details
­ A number of fish species feed on walleye fry.  They include yellow perch,
  white bass, yellow bass, smallmouth bass, rainbow smelt, saugers, bullheads,
  burbot, and (most importantly) northern pike. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
648             Michigan                     Competitors      Example                    ­               489                     111

Details
­ Alewife have been implicated as serious competitors with walleye fry for
  food items in Lake Michigan. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
649             ­                       Pred/Prey         Limit                    Cannabalism      111                     -

Details
­ Cannabalism may be the most important source of fry mortality especially
  when food is scarce.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
684             Oneida Lake       Movement           Characteristic  ­               448                     111

Details
­ When the yolk sac is completely resorbed, fry swim continuously at the
  surface. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
685             ­                    Movement           Characteristic  ­               111                     -

Details
­ Although currents are important in early dispersal from spawning grounds,
  young walleye were capable of regulating their distribution within 1­2 weeks
  after hatching.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
686             Oneida Lake          Movement          Characteristic   ­               446                     111

Details
­ Transition from a pelagic to an inshore, demersal mode by fry at a mean
  length of 35 mm was observed. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
687             ­                       Movement           Characteristic   ­               439                     111
                                Area of Water   Example             ­

Details
­ Walleye fry 25­30 m long become benthic and move toward shore into shallow,
  sheltered bays.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
688             Minnesota                  Movement          Characteristic   ­               465                     111
                                Depth     Example                  ­

Details
­ At 24 mm long walleye fry were observed close to shore in water 0.3­1.2 m deep.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
701             Oneida Lake       Light        Characteristic  + Phototaxis    448                     111

Details
­ Walleye larvae are positively phototaxic from hatching to the post­larval stage. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
706             ­                         Temperature      Example                    ­               1104                    111

Details
­ Laboratory­reared fry fed poorly at temperatures <15°C, but fed well at 21°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
707             ­                      Water Motion    Lethal                    ­               111                     -

Details
­ Wave action may cause considerable egg mortality by washing viable eggs
  up on shore, or by moving them onto poor substrates where survival is
  reduced.  Wind is important in generating adequate circulation of oxygenated
  waters in and around incubating eggs.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
752             ­                   Pred/Prey          Example             ­               528                     112

Details
­ Predation on perch fry by older perch and walleye seldom occurred before
  were 1.8 cm long. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
753             Oneida Lake       Pred/Prey             Example                    ­                    523                     112

Details
­ Walleye 9 mm long were feeding on 0+ perch.  These perch became more important
  as a food item when walleye reached 19 mm long.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1508            ­                  Pred/Prey        Characteristic  ­               1076                    1066
                                                                                        1067
Details
­ Walleye fry eat zooplankton and aquatic insects and start feeding on fish at
  1.5-2.5 cm long. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1518            ­                  Light           Prefer                  ­               1093                    1066

Details
­ Walleye fry are photopositive until becoming demersal at lengths of 25-40 mm. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1519            ­                 Light              Limit                   ­               439                     1066
                                                                                        457
Details
­ Demersal fry, juveniles, and adults are very photosensitive.  They actively
  seek the shelter of dim light during periods of strong light intensities in
  clear waters.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1520            ­                         Phys. Assoc.     Characteristic  ­               439                     1066

Details
­ They are found in deep or turbid water or in contact with the substrate
  under cover of boulders, log piles, brush, and dense beds of submerged
  vegetation during the day. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1553            Wisconsin                  Water Motion    Requirement       ­               487                     1066

Details
­ Stream velocities in spawning tributaries must be sufficient to transport
  fry downstream to lakes within the period of yolk­sac absorption (3-5 days)
  or fry perish from lack of food. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1554            ­               Temperature      Limit                    <15°C           1104                    1066

Details
­ Fry will not begin to feed at temperatures <15°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1555            ­                   Pred/Prey         Optimum                 ­               1090                    1066

Details
­ Stocked walleye fry exhibited greater survival when there was a high
  availability of newly hatched gizzard shad at stocking time.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1556            ­                 Temperature     Optimum            ~22°C           482                     1066

Details
­ Optimum temperatures for walleye growth are ~22°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1557            ­               Temperature      Limit                    £12°C or        482                     1066
                                                                           ³29°C  479

Details
­ No growth occurs at temperatures £12°C or ³29°C. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1558            ­                    Temperature      Lethal         31°­33°C            1104                    1066
                                                                                        1107

Details
­ Upper lethal temperatures for fry are 31°-33°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1559            ­                 Oxygen     Optimum                ³5 mg/l         490                     1066

Details
­ Optimum DO concentrations for fry are ³5 mg/l.    
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1560            ­                 Oxygen       Lethal              <5 mg/l         486                     1066

Details
­ DO levels <5 mg/l resulted in poor survival of stocked fry.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1561            ­                         Water Motion    Tolerate            ­               854                     1066

Details
­ Fry can withstand only slight current velocities. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1562            ­                 Water Motion    Lethal             ­               1138                    1066
                                                                                        1078
Details
­ High velocities near a reservoir outlet can result in significant fry
  losses, particularly if spawning occurs at the dam face.
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Erie       (Non-spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
607             ­                  Depth        Characteristic   ­               73                      111
                                Light            Example                 ­
                                Water Color     Example                  ­

Details
­ Fish are found in moderately shallow waters where sufficient shelter,
  turbidity or color occurs to shield eyes from ambient daytime light 
  intensities. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
614             ­                  Dissolved         Optimum             40­80 mg/l      73                      111
                                   Solids
Details
­ Optimum range for dissolved solids is ~40­80 mg/l.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
647             ­                       Competitors     Example               ­               73                      111

Details
­ Rainbow smelt are serious competitors with walleye fry for food items
  in Lake Erie.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
683             ­                         Movement           Example                    ­                445                     111

Details
­ Tagging studies indicated that adults and juveniles from the Thames River 
  (Lake St. Clair) stock moved in opposite directions during periods of
  migration.  Through late spring and summer, adults moved north from their
  spawning grounds on the Thames River in the St. Clair River and southern
  Lake Huron, while juveniles moved south through the Detroit River into the 
  western basin of Lake Erie.  Through autumn, winter, and early spring, these
  migrations were reversed.  Similar migration patterns were observed in
  Lake Erie.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
 710            ­                     Pred/Prey       Example             ­               492                     111

Details
­ Stomachs of yellow perch, spottail shiners, stonecats, and white suckers
  contained walleye eggs in Lake Erie.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
756             ­                     Pred/Prey        Example                  ­               73                      112
                                Oxygen       Example                  ­  

Details
­ In the central basin of Lake Erie, perch and smelt fry are protected
  from walleye predation because of hypolimnial oxygen depletion which
  excludes the walleye from their foraging base.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
793             ­                     Pred/Prey          Lethal             Overfishing     73                      19
                                Pred/Prey        Limit                       Benthos         426
                                Oxygen      Limit                       ­
                                Siltation          Limit                       Spawning Area

Details
­ Severe declines of walleye in Lake Erie was from overfishing and degradation of
  the environment via siltation of spawning areas, destruction of oxygen regimes
  in the western and central basins, and major changes in the benthos in these basins.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
794             ­                           Competitors      Example                   ­               73                      19

Details
­ Pressure from the rapidly increasing smelt population placed significant
  additional stress (especially in the central basin) on the walleye
  population, in addition to exploitation and eutrophication.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
795             ­                            Pred/Prey          Example             -               73                      19

Details
­ Dominant year-classes of yellow perch can exert (three years after hatching)
  a predatory pressure on YOY walleye that forces walleye abundance into a
  three­year cycle.
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Huron      (Non-spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
663             Georgian Bay         Pred/Prey        Lethal               Lamprey           491                     111

Details
­ Lamprey scars have been observed in <1% in Lake Huron. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
683             ­                        Movement             Example               ­                       445                     111

Details
­ Tagging studies indicated that adults and juveniles from the Thames River
  (Lake St. Clair) stock moved in opposite directions during periods of
  migration.  Through late spring and summer, adults moved north from their 
  spawning grounds on the Thames River in the St. Clair River and southern Lake
  Huron, while juveniles moved south through the Detroit River into the 
  western basin of Lake Erie.  Through autumn, winter, and early spring,
  these migrations were reversed.  Similar migration patterns were observed
  in Lake Erie.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
689             ­                        Movement            Example               ­               462                     111
                                Area of Water   Example                    ­

Details
­ The movement of walleye from large tributaries into Lake Huron was observed
  during periods at high water temperature in late summer.
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Michigan   (Non-spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
662             ­                          Pred/Prey           Lethal               Lamprey            459                     111

Details
­ Lamprey scars have been observed in <1% in Lake Michigan. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
675             ­                         Pred/Prey          Example             ­               121                     111

Details
­ Lake Michigan walleye fed mainly on alewives and rainbow smelt although 
  yellow perch were abundant and available. 
                                                                                                                                                             

Walleye (Stizostedion vitreum)
Lake Superior   (Non-spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
664             Nipigon Bay              Pred/Prey           Lethal              Lamprey         438                     111

Details
­ Lamprey scars have been observed in <1% in Lake Superior.
                                                                                                                                                             

Walleye (Stizostedion vitreum)
        (Non-spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
468             ­                          Competitors     Example                    ­                206                     110

Details
­ Although smallmouth bass eat many of the same items as walleyes, the
  bass's major use of crayfish made competition minimal.
                                                                                                                                                              Ref. No.       Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
585             ­                          Area of Water   Prefer                     ­               111                     -
                                Turbidity       Prefer                     ­
                                Clarity              Prefer                   ­
                                Depth      Prefer                    ­

Details
­ Walleye prefer large, semi­turbid waters.  Suitable lakes are >400 h although
  smaller waters may contain natural populations (particularly if they form part
  of a larger contiguous system).  Clear­water lakes (if sufficiently large and deep)
  may also be inhabitated by walleye.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
589             ­                    Movement           Characteristic   ­               111                     -
                                Depth      Characteristic   ­ 

Details
- As summer progresses, all age groups move to deeper waters.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
 590            Minnesota                   Movement             Characteristic  -               465                     111
                                Area of Water   Characteristic  ­               481

Details
­ Adults and sub­adults moved back inshore in early autumn.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
591             ­                      Movement          Characteristic   ­               111                     -
                                Depth      Characteristic  ­

Details
­ By late autumn and through winter, all age groups moved into deeper waters. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
592             ­                 Depth         Characteristic   ­               111                     -
                                Phys. Assoc.    Characteristic  -                                                                               Light           Example                    ­

Details
- Adult walleye generally occur in moderately-shallow waters near boulder
  shoals or rock outcrops during the daytime.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
593             ­                       Depth         Characteristic   ­               111                     -
                                Phys. Assoc.    Characteristic  ­
                                Light         Example             ­
                                Pred/Prey          Characteristic   ­
                                Movement             Characteristic   ­

Details
­ Diurnal feeding migrations occur in the morning and evening into shoal areas
  or toward the surface as light intensity reaches relatively low levels of
  illumination. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
594             ­                         Depth      Characteristic   ­               439                     111
                                Phys. Assoc.     Characteristic  ­
                                Light       Example                  ­
                                Movement            Characteristic   ­

Details
­ A large number of daylight hours may be spent in contact with the substrate
  or concealed under boulders, log piles, or brush shelters. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
595             ­                    Temperature      Characteristic   ­               111                     -
                                Clarity             Characteristic   ­
                                Movement          Characteristic   ­ 
                                Pred/Prey         Characteristic   ­ 
                                Light         Example                    ­
 
Details
­ They are usually found above the thermocline in thermally-stratified lakes.
  The hypolimnion may be penetrated for feeding forays or to seek shelter in 
   extremely clear lakes. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
597             ­                    Depth       Characteristic   ­               111                     -
                                Water Motion    Characteristic   ­

Details
­ Walleye occupy a wider depth range during winter months although fast
  currents and turbulent areas are avoided. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
598             ­                   Temperature     Prefer                  20°­23°C        215                     111

Details
­ The preferred temperature is ~20°­23°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
599             ­                              Temperature       Tolerate            0°­30°C,         111                     -
                                                                          20°­23°C
Details
- A wide range of water temperatures from 0°­30°C is tolerated.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
601             ­                       Temperature     Lethal             33°­34°C            479                     111

Details
­ Total population mortality occurred when minimum temperatures >33°­34°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
602             ­                        Light         Characteristic    Phototaxis       458                     111

Details
­ The adult walleye is negatively phototatic. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
603             ­                        Light         Characteristic   ­               470                     111
                                Pred/Prey       Characteristic   Nocturnal       439

Details
­ The adult walleye is crepuscular or nocturnal in its feeding habits.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
604             ­                        Light         Characteristic  ­               457                     111
                                Oxygen    Limit                      ­

Details
­ Where DO levels are too low to satisfy respiratory requirements, the
  reaction to light levels diminishes. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
605             ­                       Turbidity          Characteristic   ­               439                     111
                                Light       Example               ­
                                Movement          Example                    ­
 
Details
­ Walleye are tolerant of a wide range in turbidity, and are more active
  in the daytime in extremely turbid lakes.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
606             ­                       Water Colour     Characteristic   ­                 111                     -
                                Light       Example                  -
                                Movement          Example                  ­
 
Details
­ Walleye frequently occurs in humic acid­stained lakes where the dark color
  facilitates daytime activity.  They apparently tolerate a broad range of true
  water color.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
608             ­                         Oxygen       Characteristic   >3 ppm  224                     111 
Details
­ Walleyes in natural conditions generally achieve greatest abundance at DO
  concentrations >3 ppm. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
609             ­                      Oxygen      Limit                 2 ppm      457                     111

Details
- Walleye may tolerate DO concentrations in the laboratory as low as 2 ppm.
  Oxygen levels 1.0­1.5 ppm cause walleye to rise to the surface.  At 0.6 ppm,
  a loss of coordination and equilibrium occurs.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
610             ­                  CO2             Avoid                 ­               457                     111

Details
­ Increases in CO2 tension 3-10 mm Hg caused walleye to move upward into 
  surface waters. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
611             ­                        pH                Tolerate                        6­9             457                     111

Details
­ A pH range 6-9 probably has no significant effect. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
613             ­                          Dissolved           Tolerate                  ­               456                     111
                                   Solids
Details
­ Walleye tolerate a wide range in dissolved solids up to 15,000 mg/l.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
615             ­                    Organics             Tolerate                   ­               111                     -

Details
­ Walleye are tolerant of relatively large amounts of suspended and dissolved
  organic compounds if they do not create an oxygen deficit below preferred
  levels.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
616             ­                          Pollution          Tolerate                 ­               434                     111
                                                                                        435     
Details                                                                         436
­ Walleye are reasonably tolerant of moderate levels of domestic pollution.     437
  Generally intolerant of industrial effluents releasing toxic ions or           438
  creating sedimentation on the substrates from Kraft mills (sulphate) may 
  inhibit spawning and alter migration routes.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
617             ­                Phys. Assoc.    Characteristic   ­               111                     -
                                Light        Example              ­
                                Depth      Example              ­

Details
­ Preference is for a clean, hard substratum where daylight hours are
  spent with the walleye resting in contact with the bottom:  Deep, organic
  substrate is usually avoided. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
618             ­                           Phys. Assoc.     Characteristic  Vegetation       111                     -

Details
- Walleye tend to avoid dense submergent vegetation.  Sparse vegetation offers
  favorable feeding or resting areas.  Isoetes (a small submergent plant
  forming dense bottom growths 1­5 cm high) form suitable resting areas. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
619             ­                          Phys. Assoc.     Characteristic  ­               439                     111
                                Light          Example             ­

Details
­ Large boulder shoals, sunken trees, or brush shelters are sought for
  daytime shelter from high light intensities.  Resting walleyes obscure
  themselves from ambient illumination levels in the daytime by seeking 
  shelter.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
620             ­                      Ice                   Example                ­                     111                     -

Details
­ Ice is not a limiting factor unless winter kill conditions are created.
  Walleye thrive in lakes at the northern end of their range >2 m of ice. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
621             ­                   Pred/Prey          Optimum             ­               111                     -

Details
­ Lakes lacking suitable forage fishes maintain low stocks of walleye.
  Highest-standing stocks occur in lakes with abundant small percids,
  cyprinids, osmerids, percopsids, or coregonines. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
623             ­                    Pred/Prey           Characteristic  ­               111                     -
                                Water Motion    Characteristic  ­
                                Light              Characteristic   ­
 
Details
­ Feeding is restricted by ambient  light conditions.  Most active feeding 
  periods occur during the greatest percentage changes in subsurface
  illumination (usually at dusk and dawn or prior to rainstorms).  Nocturnal
  feeding is common, particularly in clear­water lakes.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
624             ­                           General            Characteristic   ­               111                     -
                                Light         Characteristic  ­
 
Details
­ The walleye is eurybiotic and tolerant of a wide range of natural abiotic
  and biotic conditions.  Extreme light sensitivity limits most of its active
  period to dim­light conditions.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
646             ­                      Pred/Prey            Characteristic   ­               111                     -

Details
­ A number of fish species feed on walleye fry.  These include yellow perch,
  white bass, yellow bass, smallmouth bass, rainbow smelt, saugers, bullheads, 
  burbot, and (most importantly) northern pike.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
648             Michigan                     Competitors     Example              ­               489                     111

Details
­ Alewife have been implicated as serious competitors with walleye fry for
  food items in Lake Michigan.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
652             ­                         Oxygen         Limit                    1.6 ppm          447                     111

Details
­ Mortalities during experiments of oxygen drawdown occurred <1.6 ppm 
  160-250 min. after oxygen drawdown began.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
653             ­                    Oxygen   Tolerate             1 ppm        457                     111

Details
­ Walleye in aquaria were able to survive oxygen drawdown to 1 ppm (150­
  200 min. after drawdown) without mortality. Loss of coordination 
  and equilibrium first occurred at 0.6 ppm.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
657             ­                 Movement            Characteristic  ­               111                     -
                                Light           Characteristic   ­
                                Pred/Prey         Characteristic   ­

Details
­ Diurnal vertical migrations of fish at dawn and dusk reflect periods of 
  optimum illumination levels for feeding.  Above and below these levels,
  feeding is reduced or non­existent. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
658             ­                          Competitors       Example             ­               63                      -

Details
­ Walleye compete with such piscivorous fish as northern pike, yellow perch,
  sauger, and smallmouth bass.  Northern pike is the most important.               
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
659             Minnesota                 Competitors       Example                   ­               480                     111

Details
­ After smallmouth were introduced into some northeastern Minnesota walleye 
  lakes, bass became the dominant species (over walleye) in the boulder/
  rubble­lined lakes with high shoreline development factors and low 
  populations of minnows and small fish.  In lakes with little shoreline 
  irregularity, moderate to extensive shoreline, shoal areas of gravel, sand
  and muck, and sizeable populations of forage fish, walleyes remained
  dominant. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
660             ­                 Pred/Prey          Example                 ­                63                      -

Details
­ Large carnivore, the adult walleye is not usually preyed upon by 
  other fish species.  Northern pike is the most important predator on
  adult walleye over much of its range.  Muskellunge prey on walleye in
  more restricted areas.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
661             ­                  Pred/Prey           Lethal         Lamprey             111                     -

Details
­ Sea lamprey predation on adult walleye is of little importance in 
  most waters.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
665             ­                          Water Motion    Example                    ­               *                       111
                                Light        Example             ­
                                Pred/Prey          Example                ­
                                Phys. Assoc.     Example             ­

Details
- Wind action on shallow reefs and the approach of storms decrease light
  intensities and stimulate daytime feeding activity of walleye.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
666             Iowa                      Phys. Assoc.    Characteristic  Bottom      441                     111
                                Depth      Characteristic   ­
                                Pred/Prey           Example                    ­

Details
­ Feeding usually occurs near or at the bottom.  During feeding periods,
  walleye may move into shallower waters to feed. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
667             ­                         Pred/Prey         Example             ­               443                     111
                                Light