Esox lucius: Northern pike Shannon Hennessey FISH 423 Aquatic Invasion Ecology Fall, 2011
Esox lucius: Northern pike
Shannon Hennessey
FISH 423 Aquatic Invasion Ecology
Fall, 2011
Diagnostic information
Scientific name
Order: Esociformes
Family: Esocidae
Genus: Esox
Species: E. lucius
Common names: Northern pike, pike,
jackfish, grand brochet
Basic identification key
The Northern pike Esox lucius can
be characterized by a long body with a ‘duck
bill’ snout, a large mouth with many sharp teeth,
and cheeks that are completely scaled. The
dorsal and anal fins are set posteriorly on the
body with a narrow caudal peduncle and a
mildly forked caudal fin. E. lucius have greenish
dorsal and lateral surfaces with yellow bars or
rows of spots running along the sides, and a
whitish ventral surface (Figure 1). Body lengths
range from 46-51 cm on average, with an
average weight of 1.40 kg (Morrow 1980).
However, in the United States these fish can
grow to sizes up to 1.5 m long with weights up
to 35 kg.
Life history and basic ecology
Life cycle
Esox lucius has a relatively simple life
cycle, in which they have 4 life stages as defined
by Inskip (1982), all of which have specific
habitat requirements. The embryo stage is when
the fish has not yet emerged from the egg.
Immediately after hatching, these become fry
until they assume adult proportions at a size of
approximately 6.5 cm (Franklin and Smith
1960). Juveniles are defined as those fish from
6.5 cm in length to the onset of sexual maturity,
or the stage at which their gonads begin to
develop. Once these fish have reached sexual
maturity, they become adults until the end of
their life cycle. These fish are typically solitary
and highly aggressive (Craig 2008).
Spawning occurs during the spring flood soon
after ice-out, when water temperatures are 8-
12°C and can last from a few days to more than
a month (Franklin and Smith 1963, Inskip 1982,
Casselman and Lewis 1996). E. lucius migrate
up tributaries and spawns in calm, shallow
waters of wetlands or flooded marshes where
there are mats of submerged vegetation. This
Figure 1: Northern pike Esox lucius color image (top) and black
and white image with diagnostic information (bottom) (Montana
State Government’s Field Guide).
vegetation is essential not only to the survival of
the eggs, but will also become important nursery
habitat once the juveniles have emerged
(Casselman and Lewis 1996, Mingelbier et al.
2008). Eggs are deposited where they then stick
to the vegetation mats, which suspend them off
of the potentially anoxic sediments until
hatching approximately two weeks later
(Franklin and Smith 1963, Casselman and Lewis
1996). Water level is a very important factor in
embryo survival, due to the fact that E. lucius
usually spawn in water as shallow as 0.1 – 0.2 m
deep (Inskip 1982). High water levels during
spawning can also be associated with larger
juveniles as the high waters bring an influx of
nutrients, increasing the productivity in areas
where larval fish are growing (Johnson 1957,
Casselman and Lewis 1996).
Once the eggs hatch, young-of-the-year fish
remain among the submerged vegetation, which
provides important nursery habitat. At hatching,
these fish are 7-9 mm in length on average
(Frost and Kipling 1967, Forney 1968, Inskip
1982). During the first few days, fry remain
attached to the vegetation until their yolk sac
was absorbed (Frost and Kipling 1967, Inskip
1982). The juveniles grow rapidly, increasing
their size and activity, and the shelter provided
by the vegetative cover helps enhance survival
(Casselman and Lewis 1996). As they grow,
juveniles move to more floating and submergent
vegetation, rather than the emergent vegetation
preferred by fry, but remain in shallow waters
(Casselman and Lewis 1996, Craig 2008).
Maturation is highly dependent on growth rate,
with males typically maturing at 34-42 cm total
length and females at 40-48 cm (Frost and
Kipling 1967; Priegel and Khron 1975). In the
US, both males and females typically mature at
about 2 years of age, although there is variation
due to differential growing conditions (Inskip
1982). E. lucius can live as long as 24 years, but
longevity is also strongly correlated with growth
rate (Miller and Kennedy 1948). At the more
southern end of their distribution, these fish may
only live up to 4 years. (Buss and Miller 1961,
Schryer et al. 1971, Inskip 1982). Adults are
also strongly associated with vegetation and
shallow waters, showing a preference for
submergent vegetation as it facilitates optimum
foraging efficiency (Casselman and Lewis 1996,
Craig 2008).
Feeding habits
E. lucius is characterized as a keystone
piscivore that can shape the composition,
abundance and distribution of fish communities
(Craig 2008). They are visual predators that are
primarily active during the day, feeding on a
wide variety of prey from invertebrates to fishes
(Polyak 1957, Carlander and Cleary 1949,
Casselman and Lewis 1996, Craig 2008). As
opportunistic feeders E. lucius will feed on prey
that is seasonally abundant, although the size of
their prey is limited by both their size and the
size of their prey (Craig 2008). They can
consume a wide range of prey sizes, but have
also been shown to be size-selective predators
(Nilsson and Bronmark 2000, Craig 2008).
Although they can be cannibalistic, this has not
been shown to comprise a large portion of their
diet (Frost 1954, Lawler 1965, Mann 1976).
Aquatic vegetation is particularly important for
feeding as these fish utilize and ‘ambush’ style
of predation (Inskip 1982, Casselman and Lewis
1996). Intermediate vegetation densities have
been associated with optimum predation
efficiency (Craig and Black 1986), and calm,
clear waters provide better visibility associated
with more efficient prey capture (Craig 2008).
Fry begin feeding once they reach a length of
approximately 10-12 mm in length, about 10
days after hatching (Franklin and Smith 1963).
They initially feed on zooplankton, but soon
begin to feed on aquatic insect larvae and fish,
marking the start of piscivory very early in their
life (Hunt and Carbine 1951, Frost 1954, Inskip
1982). Within 4-5 weeks after hatching, at a
length of approximately 50-60 mm, their diet is
comprised mostly of fish, and fry as small as 21
mm have been shown to be cannibalistic (Hunt
and Carbine 1951). As they continue to grow,
their prey is predominantly fish, although they
have been known to prey on crayfish, waterfowl
and even small mammals (Frost 1954, Lagler
1956, Seaburg and Moyle 1964, Lawler 1965,
Mann 1976, Inskip 1982).
Reproductive strategies
E. lucius is an iteroparous species,
undergoing multiple reproductive events, with a
relatively high fecundity. These fish form
spawning groups, usually consisting of one
female and either one or several males. 5-60
eggs are released at any one spot, where they are
then fertilized by males (Svardson 1949, Clark
1950). The gametes are broadcasted, with no
parental care provided post-spawning (Eddy and
Underhill 1974, Inskip 1982). Any one
spawning group can release gametes over a large
area of spawning habitat (Koshinsky 1979).
Franklin and Smith (1963) found the number of
eggs produced to be highly dependent on female
body size, described by the equation y = 4401.4x
– 66245, with y equal to the number of eggs
produced, and x as the total length of the fish in
inches. Females weighing 0.75 lbs may produce
from 9,000 to 10,000 eggs, while a female
weighing 10 lbs may produce 100,000 eggs
(Lagler 1956).
Environmental optima and tolerances
Northern pike are a cool water species,
but have a wide range of environmental
tolerances including water temperature,
dissolved oxygen concentration, and water
clarity, which, in part, can be attributed to their
success as an invasive species (Casselman 1978,
Steinberg 1992, Casselman and Lewis 1996).
These optima and tolerances, however, vary
among life-cycle stages (Inskip 1982).
E. lucius embryos are tolerant of temperatures
up to 19°C (Siefert et al. 1973), with maximum
hatching success occurring at temperatures from
9-15°C and severe mortality at temperatures
near 5°C (Hassler 1970). Dissolved oxygen
concentrations of 4.5 mg/L is optimal for
embryo development, while concentrations of
3.2 mg/L or less result in high embryo mortality
(Siefert et al. 1973). Embryos are particularly
sensitive to high rates of siltation (≥1 mm/day)
(Hassler 1970), and exposure to hydrogen
sulfide of concentrations greater than 0.014-
0.018 ppm for 96 hours decreases hatching
success (Adelman and Smith 1970a).
Fry survival and growth is greatest at
temperatures from 18.0-20.8°C, with poor
survival at temperatures lower than 5.8°C and
higher than 25.6°C (Lillelund 1966, Hokanson et
al. 1973). Hydrogen sulfide concentrations
greater than 0.004-0.006 ppm for 96 hours
significantly decreased survival of yolk sac fro
(Adelman and Smith 1970a).
Juvenile E. lucius reach maximum growth rates
at temperatures ranging from 19-21°C, with
significantly decreased survival at temperatures
lower than 3°C and above 28°C (Casselman
1978). Growth rates were hindered at dissolved
oxygen concentrations below 7 ppm, and very
low juvenile survival occurred at concentrations
below 3 ppm (Adelman and Smith 1970b).
Feeding ceased at less than 2 ppm and no fish at
dissolved oxygen concentrations of 1 ppm
survived more than 20 hours in a study by Petit
(1973).
Adults have the greatest environmental
tolerances of the life-cycle stages, with a
maximum temperature tolerance of over 30°C
(Ridenhour 1957). Optimum growth occurs at
approximately 20-21°C, but adult E. lucius have
shown no apparent stress at temperatures as low
as 0.1°C prior to freezing in a shallow lake
(Casselman 1978). Despite these wide
temperature tolerances, sudden drops in
temperature can be lethal (Ash et al. 1974,
Inskip 1982). A significant decrease in feeding
has been observed in adults exposed to dissolved
oxygen concentrations around 2-3 mg/L, and
feeding has been shown to stop altogether at
concentrations less than 2 mg/L (Adelman and
Smith 1970b, Casselman and Lewis 1996). E.
lucius can inhabit areas with pHs ranging from
6.1-8.6 (Margenau et al. 1998), and can tolerate
some salinity, having been found frequently in
the Baltic Sea (Crossman 1979).
Biotic associations
Biotic associations of E. lucius vary
across the native and introduced range of the
species, although there are numerous pathogens
and parasites that can be associated with this
species. One notable ectocommensal organism
associated with E. lucius is the ciliate
Capriniana piscium, also known as Trichophyra
piscium. C. piscium attaches to the lamellar
epithelia of the gill surface of E. lucius using
microfobrils that connect to the host cell
membrane (Lom 1971, Hofer et al. 2005; Figure
2). It was previously thought that high densities
of these organisms could cause tissue damage in
the host, however, there is no evidence of C.
piscium feeding on the host cells (Lom and
Dykova 1992). Instead, this commensal uses its
tentacles to feed on ciliates that are in the water
that passes through the fish gill lamellae (Lom
1971, Dovgal 2002, Hofer et al. 2005).
Current geographic distribution
Distribution in the United States
and the PNW
In the United States, the native
range of Esox lucius includes the
Great Lakes and Mississippi
River basins as well as Alaska,
Pennsylvania, Missouri and
Nebraska (Page and Burr 1991),
and the South Saskatchewan
River Drainage in Montana
(Holton and Johnson 1996).
However, E. lucius has been
reported to have non-native
populations in 41 states, including Washington,
Oregon and Idaho (Figures 3 and 4).
In the Pacific Northwest, E. lucius has an
established population in Coeur d'Alene Lake,
Idaho, and has been reported to have established
populations in the Spokane River in both Idaho
and Washington, as well as Lake Pend Oreille,
Idaho, and the Pend Oreille River in Washington
and Idaho. There have also been general reports
of the presence of established E. lucius
populations in the Columbia River in Oregon as
well as Washington (Fuller 2011) (Figure 4).
History of invasiveness
Esox lucius has a long history of
introduction and subsequent invasions, both in
the United States and elsewhere. This species is
historically absent from Mediterranean France,
Figure 2: C. piscium in the interlamellar space of fish
gills. The tentacles protrude from the gill surface where
they can capture prey (Hofer et al. 2005).
Figure 3: Native and invaded ranges of E. lucius in the United States (US
Geological Survey 2011).
central Italy, southern and western Greece, and
northern Scotland, but has been widely
translocated throughout Europe (Kottelat and
Freyhof 2007), introduced to Spain, Portugal,
and Ireland (Welcomme 1988), among other
locations. E. lucius has also been introduced to
Algeria, Ethiopia, Madagascar, Morocco,
Tunisia, and Uganda (Welcomme 1988, Lever
1996).
As an important game fish, the introduction
history of E. lucius outside of its native range in
the United States dates back to the 1800’s. The
first recorded introduction of Esox lucius in the
United States outside of its native range was in
the 1840’s when the United States Fish
Commission intentionally introduced the fish
into the Hudson River Basin, where it
subsequently spread to the lower Hudson River
by 1976 (Mills et al. 1997). Widespread
stocking of E. lucius in the Chesapeake Basin
began in the 1960’s in Pennsylvania, followed
by stocking in Maryland and Virginia
(Denoncourt et al. 1975). In 1992, 4000 E.
lucius fingerlings were released in the District of
Columbia, although the survival of these fishes
is unknown (Christmas et al. 2000). In
Colorado, E. lucius was introduced to the Elk-
head Reservoir of the Yampa River drainage in
1977, where they subsequently invaded the
Green River basin of Colorado and Utah in 1981
(Wick et al. 1985), with similar introduction
histories for other states with established E.
lucius populations.
Figure 4: Native and invaded range of E. lucius in the Pacific Northwest with general ranges as well as point
occurrences of populations (Adapted from the US Geological Survey 2011).
E. lucius was first introduced to the Pacific
Northwest in the early 1950’s (Brown 1971) and
now occurs throughout the Columbia River
basin. It was illegally stocked into Coeur
d'Alene Lake, Idaho, in the early 1970’s (Rich
1993), where it then spread into several other
lowland lakes in northern Idaho (McMahon and
Bennett 1996). Although E. lucius is native to
Montana in the Saskatchewan River drainage, it
has now spread throughout the state (DosSantos
1991), and has also spread to Idaho, Washington
and Oregon.
Invasion process
Pathways, vectors and routes of introduction
The primary introduction pathway of Esox
lucius is the intentional stocking of the fish for
recreational purposes (Fuller 2011). As an
important sport fish, E. lucius has been
intentionally introduced across the country
initially by the United States Fish Commission,
and later by various state agencies, to stimulate
fishing opportunities in various parts of the
country (Jenkins and Burkhead 1993; Scott and
Crossman 1973). Intentional introductions still
occur due to public pressures for fishing
opportunities, despite the risks associated with
introductions (McMahon and Bennett 1996).
Illegal stocking, or bait-bucket transfer, also
frequently occurs, in which E. lucius are
intentionally introduced to an ecosystem without
authorization. This is typically done to promote
fishing opportunities in the recipient ecosystem
for those stocking the water body, but this
unregulated introduction of E. lucius can play a
large role in facilitating the spread of this
species (McMahon and Bennett 1996).
In the Pacific Northwest, one of the initial
introductions of E. lucius was via illegal
stocking with Coeur d’Alene Lake, Idaho (Rich
1993), resulting in the subsequent spread of this
species across northern Idaho. E. lucius
populations in Washington are a result of illegal
stocking in the Flathead, Bitterroot and Clark
Fork River systems in Montana. These fish then
migrated into Lake Pend Orielle, through Idaho
by way of the Pend Orielle River, into
Washington (Washington Department of Fish
and Wildlife). In the past few years, these fish
have spread from Boundary Reservoir into the
Columbia River, and can now be found in
Oregon as well, most likely though downstream
migration in the Columbia River (McMahon and
Bennett 1996).
Factors influencing establishment and spread
The establishment and spread of a species
is determined by the environmental tolerances of
that species, as well as certain life-history
characteristics. E. lucius can withstand a wide
range of environmental conditions (Casselman
1978, Steinberg 1992, Casselman and Lewis
1996), increasing the likelihood of establishment
and spread of this species due to the fact that
there is a large amount of habitat with tolerable
environmental conditions available. E. lucius is
also a relatively fecund species (Casselman and
Lewis 1996), which may allow for rapid
establishment of populations and subsequent
spread to new areas.
The main factor that may restrict the ability of E.
lucius to establish and spread, however, is the
availability of shallow habitat with submerged
vegetation (DosSantos 1991) vital in spawning
as well as adult foraging, as well as the presence
of suitable fluctuation of water levels during the
spawning period (see life-cycle section) (Inskip
1982). The nature of these specialized habitat
requirements therefore serve to limit the
distribution and likelihood of spread (Jones
1990). Because these fish are highly predatory,
an abundant prey base in the recipient
community is also necessary to support E. lucius
populations (McMahon and Bennett 1996),
which may further constrain the amount of
suitable habitat available for colonization.
Potential ecological and/or economic impacts
There are many potential ecological and
economic impacts associated with the
introduction of E. lucius outside of its native
range. As a keystone piscivore, this fish can
shape the composition, abundance and
distribution of fish communities (Craig 2008),
which has important implications when
considering the native fish communities, as well
as sport fisheries. In places where E. lucius is
overpopulated, there is a resultant overfeeding
on their prey base, which impedes the growth of
these fish. Stunted growth, however, does not
result in lower reproduction, so overabundant E.
lucius populations can not only severely
decrease prey fish abundances (He and Kitchell
1990), but also create undesirable fisheries due
to their small size. If E. lucius populations were
left unchecked, they could cause a loss of
revenue from sport fisheries as well as have
drastic impacts on native fish populations
(Washington Department of Fish and Wildlife).
The effects that E. lucius can have on native
fishes have very important implications,
especially when considering the native fishes of
the Pacific Northwest. One of the main concerns
associated with the spread of E. lucius is the
impact this species can have on local salmon
populations (McMahon and Bennett 1996). E.
lucius have been shown to have drastic negative
impacts on salmon populations as they feed on
salmon smolts migrating to sea (Larson 1985,
Petrvozvanskiy et al. 1988) and these fish have
been associated with the extinction of local
salmonid populations (Bystrom et al. 2007,
Spens 2007, Spens and Ball 2008), making their
invasion a serious threat.
While the introduction of E. lucius threatens to
cause serious declines in a popular Pacific
Northwest sport fish, E. lucius in itself is also an
important sport fish, and there are strong
economic benefits associated with the
introduction of this species. Stocking of these
fish can generate popular sport fisheries, which
can create important revenue that enhances local
economies (McMahon and Bennett 1996).
However, this economic benefit can to lead to an
increase in the frequency of illegal stocking
(Vashro 1990, 1995), further contributing to the
continued spread of E. lucius and the harmful
effects that can follow.
Management strategies and control methods
There are several different management
strategies and control methods for Esox lucius
populations, the most effective of which,
however, is prevention. Once established, these
fish can spread to neighboring habitats,
drastically affecting the recipient biotic
communities (He and Kitchell 1990, Craig
2008), making a preemptive response the best
approach. One of the main prevention strategies
is education, allowing for an early-warning
system for new introductions in which a quick
response can be enacted, as well as increasing
awareness of the impacts of E. lucius, hopefully
deterring the intentional introduction of the
species.
However, in the cases where introduction has
already occurred, primary strategies for the
control of E. lucius include the suppression of E.
lucius populations, the prevention of spread to
other waterways, and removal of as many
organisms as possible using a variety of
methods. Prevention of spread to other
waterways is particularly important in
attempting to control E. lucius populations,
because by limiting their access to habitat it
constrains their ability to spread and establish
subsequent populations. Electrofishing, trapping
and the use of rotenone, a fish toxicant, are
common strategies for fish population
suppression and removal, although they tend to
be costly and/or labor intensive, with tradeoffs
associated with each strategy (CDF&G et al.
2006).
An important management strategy in
preventing the spread of E. lucius is regulation
of illegal introductions. Many states have laws
that prevent the transport of live fish from a
waterbody (e.g., Idaho, Oregon, and western
Montana), but there is strong opposition from
the public and it is difficult to closely manage
the actions of individuals stocking fish illegally
(McMahon and Bennett 1996). In Montana, the
legislature stiffened penalties associated with the
illegal stocking of fish, such as fines, suspension
of fishing privileges, and liability for cost of
restoring a fishery, and they have even offered
rewards for reporting such activity (McMahon
and Bennett 1996). Following the actions of the
Montana legislature in creating public incentive
seems to be a good place to start in terms of
finding better ways to raise awareness and
prevent the introduction of invasive species.
Literature cited
Adelman, I.R., and Smith, L.L. 1970a. Effect of
hydrogen sulfide on northern pike eggs and
sac fry. Trans. Am. Fish. Soc. 99:501-509.
Adelman, I.R., and Smith, L.L. 1970b. Effect of
oxygen on growth and food conversion
efficiency of northern pike. Prog. Fish-Cult.
32:93-96.
Ash, G.R., Chymko, N.R., and Gallup, D.N.
1974. Fish kill due to "cold shock" in Lake
Wabamun, Alberta. J. Fish. Res. Board
Can. 31: 1822-1824.
Brown, C. J. D. 1971. Fishes of Montana. Big
Sky Books, Bozeman, MT.
Buss, K., and Miller, J. 1961. The age and
growth of northern pike. Penn. Angler
30(3): 6-7.
Bystrom, P., Karlsson, J., Nilsson, P., Ask, J.,
and Olofsson, F. 2007. Substitution of top
predators: effects of pike invasion in a
subarctic lake. Freshw. Biol. 52: 1271–
1280.
California Department of Fish and Game, U.S.
Department of Agriculture, and the U.S.
Forest Service. 2006. Lake Davis pike
eradication project. Draft EIS/EIR.
http://www.dfg.ca.gov/northernpike/EIR-
EIS/index.html.
Carlander, K.D., and Cleary, R.E. 1949. The
daily activity pattern of some freshwater
fishes. Am. Midi. Nat. 41: 447-452.
Casselman, J.M. 1978. Effects of environmental
factors on growth, survival, and
exploitation of northern pike. Am. Fish.
Soc. Spec. Publ. 11: 114-128.
Casselman, J.M. and Lewis, C.A. 1996. Habitat
requirements of northern pike (Esox lucius).
Canadian Journal of Fisheries and Aquatic
Sciences 53(Suppl. 1): 161–174.
Christmas, J., Eades, R., Cincotta, D., Shiels,
A., Miller, R., Siemien, J., Sinnott, T., and
Fuller, P. 1998 History, management, and
status of introduced fishes in the
Chesapeake Bay basin. Proceedings of
Conservation of Biological Diversity: A
Key to the Restoration of the Chesapeake
Bay Ecosystem and Beyond. pp. 97-116.
Clark, C.F. 1950. Observations on the spawning
habits of northern pike, Esox lucius, in
northwestern Ohio. Copeia 1950(4): 258-
288.
Craig, J.F. 2008. A short review of pike ecology.
Hydrobiologia 601: 5-16.
Craig, R.A., and Black, R.M. 1986. Nursery
habitat of muskellunge in southern
Georgian Bay, Lake Huron, Canada. Am.
Fish. Soc. Spec. Publ. 15: 79–86.
Crossman, E.J. 1978. Taxonomy and
distribution of North American esocids.
Am. Fish. Soc. Spec. Publ. 11: 13-26.
Denoncourt, R.F., Robbins, T.W. and Hesser, R.
1975. Recent introductions and
reintroductions to the Pennsylvania fish
fauna of the Susquehanna River drainage
above Conowingo Dam. Proceedings of the
Pennsylvania Academy of Science 49: 57-
58.
Dickson, T. 2003. Breakthrough at Milltown
Damn. The Magazine of Montana Fish,
Wildlife, and Parks. May/June 2003 Issue.
DosSantos, J. M. 1991. Ecology of a riverine
pike population. Pages 155-159 in J. L.
Cooper, ed. Warmwater Fisheries
Symposium I. U.S. For. Serv. Gen. Tech.
Rep. RM-207.
Dovgal, I.V. 2002. Evolution, phylogeny and
classification of suctoria (Celiphora).
Protistol. 2: 194 – 270.
Eddy, S., and Underhill, J.C. 1974. Northern
fishes. Univ. Minn. Press, Minneapolis,
MN. 414 pp.
Forney, J.L. 1968. Production of young northern
pike in a regulated marsh. N.Y. Fish Game
J. 15:143-154.
Franklin, D.R., and Smith, L.L. 1960. Notes on
the early growth and allometry of the
northernpike, Esox lucius L. Copeia
1960(2): 143-144.
Frost, W.E. 1954. The food of pike, Esox lucius
L., in Windermere. J. Anim. Ecol. 23: 339-
360.
Frost, W.E., and Kipling, C. 1967. A study of
reproduction, early life, weight-length
relationship and growth of pike, Esox lucius
L., in Windermere. J. Anim. Ecol . 36: 651-
693.
Hassler, T.J. 1970. Environmental influences on
early development and year-class strength
of northern pike in Lakes Oahe and Sharpe,
South Dakota. Trans. Am. Fish. Soc. 99:
369-375.
He, X., and Kitchell, J.F. 1990. Direct and
indirect effects of predation on a fish
community: a whole lake experiment.
Transactions of the American Fisheries
Society 119: 825-835
Hofer, R., Salvenmoser, W., and Fried, J. 2005.
Population dynamics of Capriniana
piscium (Ciliophora, Suctoria) on the gill
surface of Arctic char (Salvelinus alpinus)
from high mountain lakes. Arch. Hydrobiol
162(1): 99-109.
Hokanson, K.E.F., McCormick, J.H., and Jones,
B.R. 1973. Temperature requirements for
embryos and larvae of the northern pike,
Esox lucius (Linnaeus). Trans. Am. Fish.
Soc. 102: 89-100.
Holton, G.D. and Johnson, H.E. 1996. A field
guide to Montana fishes, second edition.
Montana Department of Fish, Wildlife and
Parks. Helena, MT. 104pp.
Hunt, B.P. and Carbine, W.F. 1950. Food of
young pike, Esox lucius, L., and associated
fishes in Peterson's ditches, Houghton
Lake, Michigan. Trans. Am. Fish. Soc. 80:
67-83.
Inskip, P.D. 1982. Habitat suitability index
models: northern pike. U.S. Fish Wildl.
Serv. FWS/OBS–82/10.17.
Jenkins, R. E., and Burkhead. N.M. 1994.
Freshwater fishes of Virginia. American
Fisheries Society, Bethesda, MD.
Johnson, F.H. 1957. Northern pike year-class
strength and spring water levels. Trans.
Am. Fish. Soc. 86: 285-293.
Jones, T. S. 1990. Floodplain distribution of
fishes of the Bitterroot River, with
emphasis on introduced populations of
northern pike. Master's thesis. University of
Montana, Missoula.
Koshinsky, G.D. 1979. Northern pike at Lac La
Ronge. Part 1. Biology of northern pike.
Part 2. Dynamics and exploitation of the
northern pike population. Saskatchewan
Fish. Lab. Tech. Rep. 79-80. Dept. Tourism
Renewable Resour., Saskatoon,
Sakatchewan, Canada. 303 pp.
Kottelat, M. and Freyhof , J. 2007 Handbook of
European freshwater fishes. Publications
Kottelat, Cornol, Switzerland. 646 p.
Lagler, K.F. 1956. The pike, Esox lucius
Linnaeus, in relation to waterfowl, Seney
National Wildlife Refuge, Michigan. J.
Wildl. Manage. 20: 114-124.
Larson, K. 1985. The food of northern pike
Esox lucius in trout streams. Medd. Danm.
Fiskeri-og Havunders. (NySer.) 4: 271-326.
Lawler, G.H. 1965. The food of pike Esox
lucius, in Heming Lake Manitoba. J. Fish.
Res. Bd. Canada 22:1357-1377.
Lever, C. 1996. Naturalized fishes of the
world.. Academic Press, California, USA.
408 p.
Lillelund, V.K. 1966. Versuche zur erbrutung
der Eier vom Hecht, Exos lucius L., in
Abhängigkeit von Temperatur und Licht.
Arch. Fishereiwiss. 17: 95-113. (English
summary)
Lom, J. 1971. Trichophrya piscium: a pathogen
or an ectocommensal? An ultrastructural
study. Folia Parasitologica (Praha) 18: 197–
205.
Lom, J. and Dykovà, I. 1992. Protozoan
parasites of fishes. Development in
Aquaculture and Fisheries Sciences 26: 250
– 252.
Mann, R.H.K. 1976. Observations on the age,
growth, reproduction and food of the pike
Esox lucius (L.) in two rivers in southern
England. J. Fish Biol. 8: 179-197.
Margenau, T.L., Rasmussen, P.W., and Kampa,
J.M. 1998. Factors affecting growth of
northern pike in small northern Wisconsin
lakes. North American Journal of Fisheries
Management 18: 625-639.
McMahon, T.E., and Bennett, D.H. 1996.
Walleye and northern pike: boost or bane to
northwest fisheries? Fisheries 21(8): 6-13.
Miller, R. B., and Kennedy, W.A. 1948. Pike
(Esox lucius) from four northern Canadian
lakes. J. Fish. Res. Board Can. 7: 176-189.
Mills, E.L., Scheuerell, M.D., Carlton, J.T. and
Strayer, D. 1997. Biological invasions in
the Hudson River: an inventory and
historical analysis. Trade paperback,
University of State of New York. 51 pp.
Mingelbier, M., Brodeur, P., and Morin, J. 2008.
Spatially explicit model predicting the
spawning habitat and early stage mortality
of Northern pike (Esox lucius) in a large
system: the St. Lawrence River between
1960 and 2000. Hydrobiologia 601: 55–69.
Morrow, J.E. 1980. The freshwater fishes of
Alaska. University of. B.C. Animal
Resources Ecology Library. 248p.
Nilsson, P.A. and Bronmark, C. 2000. Prey
vulnerability to a gape-size limited
predator: behavioural and morphological
impacts on northern pike piscivory. Oikos
88: 539–546.
Page, L.M., and Burr, B.M. 1991. A field guide
to freshwater fishes of North America north
of Mexico. The Peterson Field Guide
Series, volume 42. Houghton Mifflin
Company, Boston, MA.
Petit, G.D. 1973. Effects of dissolved oxygen on
survival and behavior of selected fishes of
western Lake Erie. Bull. Ohio Biol. Surv.
New Ser. 4: 1-76.
Petrozvanskiy, V.Y., Bugaev, V.F., Shustov,
Y.A., and Shchurov, I.L. 1988. Some
ecological characteristics of northern pike,
(Esox lucius), of the Keret’, a salmon river
in the White Sea basin. Journal of
Ichthyology, Volume 28: 136-140.
Polyak, S.L. 1957. The vertebrate visual system.
University of Chicago Press. 1390 pp.
Priegel, G.R., and Krohn. D.C. 1975.
Characteristics of a northern pike spawning
population. Wis. Dept. Nat. Resour. Tech.
Bull. 86. 18 pp.
Rich, B. A. 1993. Population dynamics, food
habits, movement and habitat use of
northern pike in the Coeur d'Alene River
system. Master's thesis. University of
Idaho, Moscow.
Ridenhour, R.L. 1957. Northern pike, Esox
lucius L. , population of Clear Lake, Iowa.
Iowa State Coll. J. Sei. 32(1): 1-18.
Schryer, F., Ebert, V., and Dowlin, L. 1971.
Statewide fisheries surveys. Determination
of conditions under which northern pike
spawn naturally in Kansas reservoirs.
Dingell-Johnson Proj. F-15-R-6, Job C-3.
Final Res. Rep., Kan. Forestry, Fish Game
Comm. 37 pp.
Scott, W. B. and Crossman, E.J. 1973.
Freshwater Fishes of Canada. Department
of Fisheries and Oceans Scientific
Information and Publications Branch.
Ottawa, Canada. 966 pp.
Seaburg, K.G., and Moyle, J.B. 1964. Feeding
habits, digestive rates and growth of some
Minnesota warmwater fishes. Trans. Am.
Fish. Soc. 93: 269-285.
Siefert, R.E., Spoor, W.A. and Syrett, R.F. 1973.
Effects of reduced oxygen concentrations
on northern pike (Esox lucius) embryos and
larvae. J. Fish. Res. Board Can. 30: 849-
852.
Spens, J. 2007. Can historical names and fishers’
knowledge help to reconstruct the
distribution of fish populations in lakes? In
Fishers’ knowledge in fisheries science and
management. Edited by N. Haggan, B.
Neis, and I. Baird. Coastal Management
Sourcebooks 4. Chap. 16. UNESCO, Paris,
France. pp. 329–349.
Spens, J., and Ball, J.P. 2008. Salmonid or
nonsalmonid lakes: predicting the fate of
northern boreal fish communities with
hierarchical filters relating to a keystone
piscivore. Can. J. Fish. Aquat. Sci. 65:
1945–1955.
Sternberg, D.1992. Northern Pike and Muskie.
CY DeCrosse Inc.
Svardson, G. 1949. Notes on spawning habits of
Leuciscus erythrophthalmus (L.), Abramis
brama (L.). and Esox lucius L. Fish. Board
Sweden, Inst. Freshwater Res.,
Drottningholm 29: 102-107.
Vashro, J. 1990. Illegal aliens. Montana
Outdoors 21(4): 35-37.
Vashro, J. 1995. The "bucket brigade" is ruining
our fisheries. Montana Outdoors 26(5): 34-
37.
Welcomme, R. L. 1988. International
Introductions of Inland Aquatic Species.
FAO Fisheries Technical Paper No. 294.
Food and Agriculture Organization of the
United Nations, Rome, Italy. 318pp.
Wick, E.J., and Hawkins, J.A. 1989. Colorado
squawfish winter habitat study, Yampa
River, Colorado, 1986-1988. Final report.
Contribution 43, Larval Fish Laboratory,
Colorado State University. Fort Collins,
Colorado. 96 pp.
Other key sources of information and bibliog
raphies
California Department of Fish and Game
http://www.dfg.ca.gov/lakedavis/biology.html
FishBase
http://www.fishbase.org/summary/Esox-
lucius.html
USGS Nonindigenous Aquatic Species
Database. Pam Fuller. 2011. Esox lucius.
http://nas.er.usgs.gov/queries/FactSheet.aspx?Sp
eciesID=676 Revision Date: 6/21/2010
Washington Department of Fish and Wildife
http://wdfw.wa.gov/ais/esox_lucius/
Expert contact information in PNW
David H. Bennett
Fish and Wildlife Resources Department
University of Idaho, Moscow, ID 83844-1136
Thomas E. McMahon
Biology Department, Fish and Wildlife Program
Montana State University, Bozeman, MT 59717-
0346
Deane Osterman
Executive Director for Natural Resources
Kalispel Tribe
Kalispel Tribal Headquarters
P.O. Box 39
Usk, WA 99180
Phone: (509) 445-1147
Fax: (509) 445-1705
Current research and management efforts
Currently, there are numerous ongoing
efforts to control the spread of Esox lucius, with
a focus on eradicating populations that have
been introduced illegally. In Montana, E. lucius
removal programs have been implemented in the
Milltown Dam Reservoir to help restore native
cutthroat and bull trout. The dam impedes
salmonid migration causing them to concentrate
in the reservoirs, providing easy prey for the E.
lucius that reside there (Dickson 2003). The
Montana Department of Fish, Wildlife, and
Parks have temporarily lowered the later levels
of the reservoir each year to kill yearling E.
lucius that occupy the back channels, resulting
in reduced fish populations, although the process
is labor intensive. Montana has also recruited
angler organizations to help control E. lucius
populations, as well as prevent illegal
introductions (McMahon and Bennett 1996).
The California Department of Fish and Game
(CDF&G) has been treating a lake with an E.
lucius population with rotenone, a common fish
toxicant, in an attempt to eradicate the fish. The
first time this was done, E. lucius were found
two years later, so another eradication attempt is
planning to be undertaken (CDF&G et al. 2006).
Experimental control measures such as the use
of net barriers, electrofishing, and encircling
nets are also being used to control E. lucius
populations, as well as the blockage of spawning
areas, reducing food availability, increasing
public awareness and implementing a
comprehensive fish monitoring program.
In Washington, management efforts are being
directed towards minimizing the impacts of E.
lucius on native fish species and reducing E.
lucius abundances in the Box Canyon Reservoir.
The Washington Department of Fish and
Wildlife (WDFW) is working with the Kalispel
Tribe Natural Resources Department (KNRD) to
devise an appropriate management strategy for
the Pend Orielle River. Surveys are being
conducted to determine the relative abundances
of E. lucius, the structure of the overall fish
community, and the timing of E. lucius
spawning activities. The WDFW is attempting to
learn more about the impacts of E. lucius on
native salmonid populations, using events that
occurred in south-central Alaskan watersheds as
a model to attempt to prevent similar damage to
Washington salmonid populations, and has
proposed to remove E. lucius’s classification as
a game fish, causing it to be listed solely as a
prohibited species.