Muskellunge (Esox masquinongy)
        (Fertilized Egg)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
370             Wisconsin                 Temperature      Example                 ­               322                     109

Details
­ Hatching occurs in 8­14 days at 12°­17°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
371             Wisconsin               Temperature     Example                  ­               350                     109

Details
­ Hatching occurs in 13­21 days at 10°­21°C, and in 6 days at 20°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
372             Wisconsin               Temperature     Limit                   ­               322                     109
                                Water Level     Limit                   ­

Details
­ A factor limiting muskellunge reproduction is the presence of cold water 
  temperatures and fluctuating water levels at spawning time. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1158            ­                  Oxygen          Requirement     ­                     809                     798

Details
­ High DO levels are critical for developing embryos and larvae. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1159            ­                 Phys. Assoc.    Requirement     ­               822                     798

Details
­ If muskellunge spawn on vegetation, enough structure is provided to keep
  eggs off the bottom yet allow for the circulation of water (as with
  northern pike). 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1160            ­                  Phys. Assoc.    Lethal                   ­               807                     798 

Details
­ Eggs may be covered by detritus and silt, which can cause anoxic conditions.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1161            ­                 Oxygen          Lethal               ­               809                     798

Details
­ Some spawning habitats may have a high BOD, which may cause micro-
  stratification in the DO at the bottom­water interface.  This results 
  in anoxic conditions around the developing eggs.       
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1162            ­                  Hydrogen        Lethal                  ­               799                     798
                                  Sulphide

Details
­ Depletion of DO near the bottom limits muskellunge reproduction success.  
  Microstratification may also allow toxic substances such as hydrogen sulfide
  (H2S) to increase to toxic levels, causing mortality in developing embryos. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1165            ­                  Temperature     Example                 ­               322                     798

Details
­ Hatching occurs in 8­14 days at 12.2°­16.7°C water temperatures. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1181            ­               Water Level     Lethal                  ­               63                      798

Details
­ Decreasing springtime water level strands spawners and young and exposes
  eggs.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1208            ­                 Oxygen    Limit                      3.2 mg/l                808                     798

Details
­ Habitat rehabilitation measures are needed in muskellunge spawning substrate
  if the DO concentration falls below 3.2 mg/l. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1209            ­                 Depth      Characteristic  <1 m            798                     -
                                Water Level     Lethal                    ­

Details
­ Because muskellunge generally spawn in water <1 m deep, declining water
  levels can affect embryos, larvae, and, possibly, fingerlings and adults may
  be stranded.  Embryos and newly hatched larvae are immobile until the yolk
  sac is absorbed and are the most vulnerable to a decline in water level.
  As muskellunge larvae grow, they are more likely able to avoid receding
  water levels. 
                                                                                                                                                             

Muskellunge (Esox masquinongy)
Lake Huron      (Juvenile)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1170            Southern                Phys. Assoc.    Characteristic  ­               805                     798
                  Georgian Bay   Depth           Characteristic  1 m 
                                Temperature     Characteristic  24°C

Details
­ Typical nursery habitat in southern Georgian Bay, Lake Huron, for 50­mm
  (range 16­98 mm) muskellunge was composed of eight families of emergent 
  and floating vegetation and nine species of submergent vegetation.  Sedge 
  was the most abundant emergent family.  Bushy pondweed, Chara spp., 
  and variable pondweed were the predominant submergent species.
  Emergent and floating vegetation were most common near shore and
  decreased in density as mean depth increased.  Submerged vegetation 
  increased in density off shore.  These nursery areas were 1 m deep,
  and substrate consisted of sand, muck, and a silt­detritus mixture.
  In the nursery areas, 19 other fish species were found with largemouth
  bass, yellow perch, and pumpkinseed the most common.  The mean water
  temperature was 24°C in the nursery habitats.  
                                                                                                                                                             

Muskellunge (Esox masquinongy)
        (Juvenile)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
374             ­                   Temperature     Limit                >30°C           376                     109
                                Turbidity       Limit                     ­
                                Light             Characteristic  Night 

Details
­ Fingerling feeding drops off as water temperature exceeds 30°C.  Turbid 
  waters interfere with feeding.  There is probably little feeding after dark. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
523             ­                    Pred/Prey       Example                 ­               209                     110

Details
­ Introduction of muskellunge into a lake eliminated most young bass survival. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1171            ­                Movement        Example                  ­               818                     798

Details
­ Movements and habitat selection of stocked muskellunge averaging ~300 mm
  were documented.  Movements of stocked muskellunge across large expanses
  of open water were rare, and mean daily movements averaged ~100 m.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1172            Whitefish Lake, Movement        Characteristic  ­               818                     798
                  Wisconsin              Phys. Assoc.    Prefer                   ­
                Trego Lake,             Area of Water   Prefer                  ­
                  Wisconsin              Temperature     Tolerate                 32.2°C

Details
­ In Whitefish Lake, Wisconsin, fish established small home ranges, and
  preferred areas with bulrush and pondweed or areas with well­developed 
  structures (sand bars or rocky points).  In Trego Lake, Wisconsin, 
  stocked fish used areas near fallen trees, boat docks, and an offshore 
  shoal on which watermilfoil and wild celery were the dominant submerged
  vegetation.  Juvenile muskellunge can withstand water temperature as 
  high as 32.2°C. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1195            ­                Temperature     Limit                    32.5°C          820                     798

Details
­ Juvenile muskellunge have an upper lethal temperature of 32.5°C.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1196            -               Pred/Prey        Characteristic  ­                   830                     798

Details
­ Size selectivity of forage fish may start at a very early age. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1198            ­                 Oxygen   Tolerate                   <1 mg/l         816                     798

Details
­ Muskellunge avoid anoxic waters and concentrate in areas of higher oxygen 
  as DO diminishes in a lake.  Juveniles can survive, for short periods of
  time, at DO <1 mg/l.
                                                                                                                                                             

Muskellunge (Esox masquinongy)
        (Larva)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
372             Wisconsin                 Temperature     Limit                      ­               322                     109
                                Water Level     Limit                       ­

Details
­ Factors limiting muskellunge reproduction are the presence of cold water
  temperatures and fluctuating water levels at spawning time.  
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
373             Wisconsin                Pred/Prey        Characteristic  ­               322                     109

Details
­ Muskellunge fry feed on live zooplankton the first four feeding days.  If 
  forage fish are not present, they may continue on it for >30 days.  Live
  forage fish are preferred after four days and usually required after 
  muskellunge are >40 mm. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1131            ­               Pred/Prey       Characteristic  ­               798                     -

Details
­ Newly hatched muskellunge begin feeding on zooplankton soon after the yolk
  sac is absorbed and fry swim up. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1132            ­                         Pred/Prey         Characteristic  ­               1122                    798

Details
­ After reaching a length of ~40 mm, muskellunge switch to a piscivorous
  diet.  This switch may occur at ~30 mm in some individuals.  In a hatchery, 
  catostomid fry were consumed by muskellunge 30 mm long.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1158            ­                  Oxygen    Requirement     ­               809                     798

Details
­ High DO levels are critical for developing embryos and larvae. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1166            ­               Movement        Characteristic  ­               1132                    798

Details
­ Upon hatching, larval muskellunge remain quiescent for the first few days
  of life while the yolk sac is absorbed.  The same limitations on embryo
  survival also apply to larvae for ~7­14 days (depending on water
  temperatures). 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1167            ­               Hydrogen        Limit                   0.004­0.006 ppm 799                     798
                                  Sulfide
Details
­ Exposure to concentrations as low as 0.004­0.006 ppm H2S decreases
  survival and growth of sac-fry northern pike. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1168            ­                  Pred/Prey       Lethal             ­               812                     798
                                                                                        350
Details
­ Newly hatched muskellunge are eaten by predacious diving beetles, giant
  water bugs, and other predacious insect larvae.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1169            ­                  Depth            Characteristic  ­               798                     -
                                Pred/Prey       Limit                   -

Details
­ Young muskellunge lie just under the water surface waiting for forage to
  pass.  At this stage, they are subject to predation by fish and birds. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1204            ­                        Temperature     Limit           36.1°C          820                     798

Details
­ Larval muskellunge have an upper lethal temperature of 36.1°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1209            ­               Depth           Characteristic  <1 m            798                     -
                                Water Level     Lethal             ­

Details
­ Because muskellunge generally spawn in water <1 m deep, declining water
  levels can affect embryos, larvae, and, possibly, fingerlings and adults may
  be stranded.  Embryos and newly hatched larvae are immobile until the
  yolk sac is absorbed and are the most vulnerable to a decline in water
  level.  As muskellunge larvae grow, they are more likely able to avoid
  receding water levels.
                                                                                                                                                             

Muskellunge (Esox masquinongy)
        (Non-spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
366             Wisconsin                  Temperature      Example             20°C            322                     109

Details
­ Greatest growth occurs in June and September when available forage is at
  a maximum and water temperatures are more favorable (~20°C).
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
375             ­                   Pred/Prey       Characteristic  ­               109                     -

Details
­ Adults eat mostly fish.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
376             Wisconsin                 Pred/Prey          Example                    ­               209                     109
                                                                                        288
Details
­ Introduction of muskellunge into two Wisconsin lakes eliminated most of the
  yellow perch and largemouth bass >100 mm long.  Enough muskellunge
  remained, apparently in secure habitats, to reproduce successfully each 
  year.  Smallmouth bass were relatively secure from muskellunge 
  predation and increased in abundance as largemouth bass decreased.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
523             ­                Pred/Prey       Example                  ­               209                     110

Details
- Introduction of muskellunge into a lake eliminated most young bass survival. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
770             ­               Pred/Prey       Example                 ­               63                      -
                                                                                        112
Details
­ Almost all warm- to cold-water predatory fish will eat perch, including
  basses (Morone spp. and Micropterus spp.), sunfish, crappies, walleye,
  sauger, pike, muskellunge, and lake trout. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1133            ­                Pred/Prey        Characteristic  ­               804                     798
                                Depth            Characteristic  ­               813

Details
­ Two studies found that muskellunge were not significantly selective about
  prey selection (by species) and appeared to be midwater feeders. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1134            ­                  Pred/Prey          Example                 ­               798                     -

Details
­ Muskellunge consume catostomids, percids, coregonids, cyprinids,
  centrarchids, clupeids, and ictalurids.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1135            ­                 Pred/Prey        Example             ­               821                     798

Details
­ Gizzard shad is probably the best forage fish for esocids, but shad rarely
  occur in the muskellunge's native range.                                      
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1147            ­                     Water Level     Limit                   ­               808                     798
                                Competitors     Limit                   ­
                                Alkalinity      Limit                   ­

Details
­ A study that examined a variety of information on watershed characteristics, 
  water chemistry, hydrology, fish communities, and cultural perturbations
  found that nine variables (out of 94) accounted for 57% of the variability
  in muskellunge reproduction.  Conditions in identified lakes most strongly 
  promoting natural reproduction were limited northern pike abundance, 
  rising springtime water levels, high alkalinity, a high shoreline develop-
  ment factor, and drainage lake systems that increase lake area and allow 
  rising spring water levels.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1148            ­               Area of Water   Characteristic  ­               798                     -
                                Phys. Assoc.    Characteristic  ­
  
Details
­ Muskellunge are found in a variety of river and lake types throughout 
  their native range.  Muskellunge are often associated with aquatic
  vegetation or submerged structures (rock reefs, fallen trees). 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1149            ­                   Movement        Characteristic  ­               806                     798

Details
­ Muskellunge in lacustrine and riverine habitats have defined home ranges 
  that vary from 300­800 m in a stream to a lake with a 300-m diameter circle.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1150            Wisconsin               Movement         Characteristic  ­               807                     798

Details
­ Home range in lacustrine habitats varied from 0.2­27.7 ha in Black Lake 
  (52 ha) and Moose Lake (676 ha), Wisconsin.  Home ranges of these
  muskellunge were smaller during winter, intermediate during summer, and
  larger in May, September, and October. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1151            Stony Lake,             Movement         Characteristic  ­               827                     798
                  Nogies Creek,
                    Ontario

Details
­ In Nogies Creek (35 ha) and Stony Lake (3,725 ha), muskellunge had home
  ranges that varied from 1.1­7.2 ha.  These fish established both winter
  and summer home ranges, but the size of the home range correlates with 
  muskellunge size.   
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1152            West Okoboji            Movement         Characteristic  ­               826                     798
                  Lake, Iowa

Details
­ In West Okoboji Lake (1,540 ha), Iowa, muskellunge had home ranges that
  averaged 146 ha (range 39­443 ha).  Eight muskellunge used the same home
  range in consecutive summers.  Muskellunge home ranges in West Okoboji
  Lake were broadly overlapping, and, occasionally, two or more fish were
  found in close proximity to each other.  It was concluded that muskellunge
  in West Okoboji Lake were not territorial.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1153            Leech Lake,             Movement        Example                 ­               834                     798
                  Minnesota

Details
­ In Leech Lake (45,134 ha), Minnesota, home range size depended on the  
  basin of Leech Lake in which the muskellunge were located.  During summer,
  Leech Lake fish had large home ranges when compared to other studies
  (ranging from 200­3,390 ha).  Winter home ranges (50­1,840 ha) were smaller 
  than summer home ranges.  Muskellunge found in larger areas of the lake 
  had separate winter and summer home ranges.  Muskellunge in a smaller 
  bay had winter home ranges that were contained in the summer home ranges.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1154            ­                General             ­                              ­               798                     -

Details
­ Lake size, season, and size of the muskellunge all affect the location and 
  size of the home range selected by individual muskellunge.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1173            ­                 Temperature       Optimum                 25.6°C          63                      798

Details
­ Optimum water temperature for muskellunge is 25.6°C. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1174            ­                     Phys. Assoc.     Characteristic  ­               826                     798
                                                                                        834
Details
­ Adult muskellunge locations were correlated with physical structures 
  (weed beds, rock reefs, and changes in bottom contour) in Leech Lake,
  Minnesota. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1175            West Okoboji            Movement        Characteristic  ­               826                     798
                  Lake, Iowa             Phys. Assoc.    Characteristic  ­
                                Light           Characteristic  ­
Details
­ Muskellunge adjusted basic foraging patterns to maintain an optimal
  feeding strategy in response to seasonally changing environmental factors.
  After the spawning period and through midsummmer, fish behaved as
  searching predators shown by relatively high levels of activity, extensive
  movements, utilization of a variety of water depths and habitat types, and 
  pronounced crepuscular (twilight) activity.  By late summer, the fish
  exhibited behavioral characteristics of a sedentary ambush predator 
  (reduced activity, strong allegiance to activity centers associated with 
  vegetation, and little diel variation).
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1176            Kentucky                Phys. Assoc.    Characteristic  ­               825                     798
                                Area of Water   Example                    ­               800

Details
­ In streams, muskellunge are associated with pools, sections of river with
  low gradients, and fallen trees. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1178            ­                 Area of Water   Limit                    -               803                     798

Details
­ Stream impoundment eliminates riverine habitat.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1180            ­                Phys. Assoc.    Lethal               ­               836                     798

Details
­ Channelization eliminates habitat.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1182            ­                   Eutrophication  Limit                      ­               809                     798
                                Phys. Assoc.    Limit                      ­

Details
­ Eutrophication (excessive weed growth and buildup of organic substrates)
  affects muskellunge.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1183            -               Eutrophication  Limit                 ­               807                     798
                                Oxygen           Limit                 ­

Details
­ Eutrophication (low winter DO) affects muskellunge. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1185            ­                 Turbidity         Limit                     ­               814                     798
                                                                                        778
Details
­ Suspended solids level impairs sight feeding.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1186            ­                  Phys. Assoc.    Limit                    ­               802                     798
                                                                                        805
Details                                                                         836
­ Elimination of vegetation causes elimination of habitat. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1187            Kentucky                    Phys. Assoc.    Limit                      ­               800                     798

Details
­ Loss of woody cover affects muskellunge.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1188            Kentucky                pH                 Limit                 ­               800                     798 

Details
­ Acid mine drainage affects muskellunge.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1189            Kentucky                  Salinity          Limit                       ­               800                     798

Details
­ Brine drainage from oil wells affects muskellunge.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1190            Kentucky                 Phys. Assoc.    Limit                     ­               800                     798

Details
­ Gravel dredging affects muskellunge.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1191            Kentucky                     Phys. Assoc.    Limit                  ­                   800                     798
                                                                                        805
Details
­ Clearing trees in riparian zones for recreational use affects muskellunge.                                      
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1192            Lake Okoboji,   Clarity            Example                ­               826                     798
                  Iowa           Movement        Example                    ­ 

Details
­ Muskellunge activity is a positive association with water transparency.  As
  water transparency decreased, so did the percentage of active muskellunge, 
  but this relationship was confounded with other factors, such as water 
  temperature.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1193            Wisconsin                 Turbidity         Example                 ­               819                     798
                                Clarity            Example                  ­

Details
­ The density of legal­sized muskellunge in Wisconsin was positively 
  correlated with turbidity and negatively correlated with Secchi depth. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1194            ­                   Phys. Assoc.    Characteristic  ­               322                     798
                                Pred/Prey        Prefer                  ­  

Details
­ Good populations of muskellunge are most often associated with excellent
  populations of suckers, whitefish, and ciscoes.  Soft­finned forage fishes
  are preferred by muskellunge.  They appear to prosper where well­balanced
  populations of these species are abundant. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1197            ­                Pred/Prey        Prefer                    ­               830                     798

Details
­ Muskellunge size and preferred prey size are related by the following 
  equation (r2 = 0.5214).  Muskellunge length (in.) = 1.1513 (prey length 
  (in.)) + 26.4173.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1199            ­                  Oxygen       Limit                 3 mg/l          798                     -

Details
­ Muskellunge overwinter with no adverse effects in lakes that maintain at
  least 3.0 mg/l DO during ice­covered periods. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1200            ­                         Temperature      Optimum                 24°C            215                     798
                                                                                        832
Details
­ The optimum overall temperature for muskellunge is ~24°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1201            ­                Temperature     Optimum                  23°C            1133                    798

Details
­ The optimum temperature for growth is 23°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1202            ­                Temperature     Limit                       25.6°C          63                      798

Details
­ The upper limit of the preferendum is 25.6°C. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1203            ­                    Temperature      Tolerate                  32.2°C          798                     -

Details
­ Temperatures will be in the optimum range during the warming and cooling
  phases of a body of water if the maximum water temperature is slightly 
  higher than the optimal temperature.   Muskellunge can withstand water
  temperature as high as 32.2°C, but this is at the upper end of their 
  tolerance, so waters that warm more than this are less suitable. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1205            ­                 Temperature     Characteristic  ­               798                     -

Details
­ Adults are the most sensitive life stage to water temperature. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1206            ­                  Depth           Example             <2 m            807                     798
                                Temperature     Example                   24°­27°C 

Details
­ During the summer months, adult muskellunge were found in water <2 m 
  deep at temperatures of 24°­27°C.                                        
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1207            ­                Phys. Assoc.    Optimum                 ­               798                     -

Details
­ Optimal habitat has extensive submerged or emergent aquatic vegetation
  interspersed with open water. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1210            ­               Competitors     Limit                      ­               810                     798
                                                                                        823
Details
­ The invasion of native muskellunge lakes by northern pike is often
  followed by the establishment of pike and subsequent decline of muskellunge. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1211            ­                   Competitors     Limit                     ­               1132                    798

Details
­ Increased angling pressure may work in favor of northern pike and be
  detrimental to muskellunge. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1212            ­                        Competitors       Limit                       ­               823                     798
                                Pred/Prey       Lethal                   ­

Details
­ Earlier spring spawning, shorter generation time, a more-aggressive nature,
  and greater food-conversion efficiency have been suggested as possible
  advantages for northern pike.  Predation by YOY northern pike on YOY 
  muskellunge is the most viable hypothesis.  In lakes with viable populations
  of both species, there must be sufficient spawning habitat to permit spatial
  separation of the species.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1213            ­                 Competitors     Limit                     ­               798                     823

Details
­ Cultural development may be responsible for northern pike out­competing 
  muskellunge.  Northern pike may be favored by cooler temperatures and a
  more­lentic habitat.  Cultural development often results in the conversion 
  of lotic habitat to lentic habitat.  Since the muskellunge is more adapted
  to life in flowing waters, this phenomenon favors the more­lentic northern
  pike. 
                                                                                                                                                             

Muskellunge (Esox masquinongy)
Lake St. Clair  (Spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1141            ­                  Phys. Assoc.    Example             ­               817                     798
                                Depth            Example                 >9 m

Details
­ Muskellunge in Lake St. Clair, Michigan, also spawned in deep, open 
  water (>9 m) with little or no vegetation. 
                                                                                                                                                             

Muskellunge (Esox masquinongy)
        (Spawning Adult)

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
367             Wisconsin             Temperature     Optimum              13°C            322                     109

Details
­ Spawning may occur at 9.5°­15.5°C; 13°C is optimum.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
368             Wisconsin                  Area of Water   Characteristic  ­                  322                     109
                                Depth       Characteristic  ­
 
Details
­ Eggs are deposited indiscriminately over several hundred yards of
  shoreline in water 150-760 mm deep.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
369             Wisconsin                   Movement            Characteristic  ­               322                     109

Details
­ Adult spawners return to the same spawning ground in consecutive years.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1136            ­                   Temperature      Optimum            12.8°C             63                      798

Details
­ Muskellunge spawn in spring when water temperature is 9.4°­15.0°C.  
  Optimum spawning water temperature is 12.8°C. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1137            ­                  Movement            Characteristic  ­               807                     798
                                Temperature     Requirement     ­
 
Details
­ Muskellunge moved to spawning grounds when water temperature reached
  8°­10°C.  They remained for 5­10 days until water temperature reached ~14°C. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1138            Nogies Creek,   Movement         Characteristic   ­               827                     798
                  Ontario                    Temperature      Requirement      ­

Details
­ In Nogies Creek, Ontario, muskellunge moved to spawning grounds when 
  water temperature was 8.0°­10.5°C.  Spawning occurred in temperatures of 
  10.5°­15.5°C.  Males abandoned the spawning grounds when water
  temperature reached 16°C.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1139            Leech Lake,               Movement        Example             ­               834                     798
                  Minnesota               Temperature       Requirement     11.6°­14.0°C

Details
­ Muskellunge in Leech Lake, Minnesota, moved to spawning grounds shortly
  after ice­out, when water temperature was 8.3°­11.6°C.  Movement to
  spawning grounds (up to 21 km) was direct and often included crossing large
  expanses of open water.  Males were the first fish on the spawning
  grounds and remained there longer than females.  Spawning occurred 
  15­35 days after ice­out at water temperatures of 11.6°­14.0°C.  Both 
  sexes (especially females) were sensitive to drops in water temperature.
  Females moved into deeper waters when water temperature cooled.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1140            Leech Lake,        Phys. Assoc.    Example                   ­               834                     798
                  Minnesota               Depth      Example                   1-2 m
                                Oxygen       Example               ­

Details
­ In Leech Lake, spawning areas chosen were in open­water areas with depths
  of 1­2 m, over a soft calcareous substrate, with Chara spp. as the dominant
  vegetation.  There was no microstratification of DO at the substrate­water
  interface during the time of egg incubation.  Temperature was uniform 
  throughout the water column.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1142            ­                        Area of Water   Example                    ­               811                     798

Details
­ Muskellunge also spawn in tributary streams and shallow lake channels.
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1143            Wisconsin                  Depth        Characteristic  <1 m            807                     798
                                Phys. Assoc.    Characteristic  ­
                                Area of Water   Example                ­
Details
­ Radio­tagged muskellunge in Wisconsin spawned in water <1 m, on a
  substrate of muck or muck and sand covered with debris or dead 
  vegetation.  Three of four spawning areas identified were in bays with
  influent streams. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1144            Nogies Creek,   Phys. Assoc.    Characteristic  ­               827                     798
                  Ontario                 Depth        Characteristic   <1 m

Details
­ Spawning substrate consists of matted vegetation and tree leaves that
  fell the previous fall.  Substrate area was <1 m deep (mean depth = 0.65 m) 
  upstream of Nogies Creek, Ontario.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1145            Michigan                   Area of Water   Characteristic  ­               831                     798
                                Phys. Assoc.    Characteristic  ­

Details
­ One  muskellunge strain spawned at the edge of channels over detritus.
  Another muskellunge strain spawned in shallow bays in Michigan.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1146            ­                     Area of Water   Characteristic  ­               803                     798
                                Water Motion    Characteristic  ­

Details
­ Spawning habitat in rivers is usually associated with low­gradient pools.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1147            -               Water Level      Limit                      ­               808                     798 
                                Competitors      Limit                 ­
                                Alkalinity      Limit                     ­

Details
­ A study that examined a variety of information on watershed characteristics,
  water chemistry, hydrology, fish communities, and cultural perturbations
  found that nine variables (out of 94) accounted for 57% of the variability 
  in muskellunge reproduction.  Conditions in identified lakes most strongly
  promoting natural reproduction were limited northern pike abundance, 
  rising springtime water levels, high alkalinity, a high shoreline develop-
  ment factor, and drainage lake systems that increase lake area and allow
  rising spring water levels. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1155            ­                         Phys. Assoc.    Example             ­               63                      798
                                Depth           Example                 -               827     
                                                                                        807
Details                                                                         809
­ Some strains of muskellunge will spawn in <1 m of water on flooded
  vegetation, detritus, and woody debris. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1156            ­                    Depth           Example                 ­                      817                     798
                                    Phys. Assoc.    Example                    ­                   834       

Details
­ Muskellunge will spawn in deeper water (>1.5 m) on beds of Chara spp. or
  areas of little vegetation.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1157            ­                Phys. Assoc.     Characteristic  ­               798                     -
                                Depth            Characteristic  ­

Details
­ No type of vegetation, depth, or substrate is critical to reproduction, 
  but muskellunge spawning habitat varies.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1163            ­                    Water Level      Limit                 ­               1131                    798

Details
­ Low water levels during spawning will negatively impact muskellunge and
  produce poor year-classes. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1164            ­                         Water Level     Optimum            ­               808                     798

Details
- Rising spring water levels have been positively correlated with 
  muskellunge reproductive success.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1177            ­                        Phys. Assoc.     Limit                      -               836                     798
                                                                                        800
Details
­ Stream impoundment blocks spawning migration. 
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1179            ­                       Phys. Assoc.     Lethal               ­               801                     798
                                                                                        836
Details
­ Draining wetlands and filling marshes eliminate spawning areas. 
                                                                                                                                                             

                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1181            ­               Water Level     Lethal                    ­               63                      798

Details
­ Decreasing springtime water level strands spawners and young and 
  exposes eggs.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1184            ­                          Siltation           Lethal                ­               778                     798
                                                                                        800
Details
­ Sediments cause loss of spawning habitat.
                                                                                                                                                             
Ref. No.        Locality (Stock)        Factor(s)       Influence(s)    Data            Primary Ref. No.                Review No.
1209            ­                    Depth       Characteristic  <1 m            798                     -
                                Water Level     Lethal             ­

Details
­ Because muskellunge generally spawn in water <1 m deep, declining water
  levels can affect embryos, larvae, and, possibly, fingerlings and adults 
  may be stranded.  Embryos and newly hatched larvae are immobile until 
  the yolk sac is absorbed and are the most vulnerable to a decline in 
  water level.  As muskellunge larvae grow, they are more able to avoid
  receding water levels.