Quick viewing(Text Mode)

Esox Lucius: Northern Pike

Esox Lucius: Northern Pike

Esox lucius:

Shannon Hennessey

FISH 423 Aquatic Invasion Ecology

Fall, 2011

Diagnostic information

Scientific name : Family: : : E. lucius

Common names: Northern pike, pike, jackfish, grand brochet Figure 1: Northern pike Esox lucius color image (top) and black and white image with diagnostic information (bottom) ( Basic identification key State Government’s Guide).

The Northern pike Esox lucius can by Inskip (1982), all of which have specific be characterized by a long body with a ‘ habitat requirements. The embryo stage is when bill’ snout, a large mouth with many sharp teeth, the has not yet emerged from the egg. and cheeks that are completely scaled. The Immediately after , these become fry dorsal and anal fins are set posteriorly on the until they assume adult proportions at a size of body with a narrow caudal peduncle and a approximately 6.5 cm (Franklin and Smith mildly forked caudal fin. E. lucius have greenish 1960). Juveniles are defined as those fish from dorsal and lateral surfaces with yellow bars 6.5 cm in length to the onset of sexual maturity, rows of spots running along the sides, and a or the stage at which their gonads begin to whitish ventral surface (Figure 1). Body lengths develop. Once these fish have reached sexual range from 46-51 cm on average, with an maturity, they become adults until the end of average weight of 1.40 kg (Morrow 1980). their life cycle. These fish are typically solitary However, in the these fish can and highly aggressive (Craig 2008). grow to sizes up to 1.5 m long with weights up Spawning occurs during the spring flood soon to 35 kg. after ice-out, when water temperatures are 8- 12°C and can last from a few days to more than Life history and basic ecology a month (Franklin and Smith 1963, Inskip 1982, Casselman and Lewis 1996). E. lucius migrate Life cycle up tributaries and spawns in calm, shallow Esox lucius has a relatively simple life waters of wetlands or flooded marshes where cycle, in which they have 4 life stages as defined there are mats of submerged vegetation. This vegetation is essential not only to the survival of Maturation is highly dependent on growth rate, the eggs, but will also become important nursery with males typically maturing at 34-42 cm total habitat once the juveniles have emerged length and females at 40-48 cm (Frost and (Casselman and Lewis 1996, Mingelbier et al. Kipling 1967; Priegel and Khron 1975). In the 2008). Eggs are deposited where they then stick US, both males and females typically mature at to the vegetation mats, which suspend them off about 2 years of age, although there is variation of the potentially anoxic sediments until due to differential growing conditions (Inskip hatching approximately two weeks later 1982). E. lucius can live as long as 24 years, but (Franklin and Smith 1963, Casselman and Lewis longevity is also strongly correlated with growth 1996). Water level is a very important factor in rate (Miller and Kennedy 1948). At the more embryo survival, due to the fact that E. lucius southern end of their distribution, these fish may usually in water as shallow as 0.1 – 0.2 m only live up to 4 years. (Buss and Miller 1961, deep (Inskip 1982). High water levels during Schryer et al. 1971, Inskip 1982). Adults are spawning can also be associated with larger also strongly associated with vegetation and juveniles as the high waters bring an influx of shallow waters, showing a preference for nutrients, increasing the productivity in areas submergent vegetation as it facilitates optimum where larval fish are growing (Johnson 1957, foraging efficiency (Casselman and Lewis 1996, Casselman and Lewis 1996). Craig 2008). Once the eggs hatch, young-of-the-year fish remain among the submerged vegetation, which Feeding habits provides important nursery habitat. At hatching, E. lucius is characterized as a keystone these fish are 7-9 mm in length on average piscivore that can shape the composition, (Frost and Kipling 1967, Forney 1968, Inskip abundance and distribution of fish communities 1982). During the first few days, fry remain (Craig 2008). They are visual predators that are attached to the vegetation until their yolk sac primarily active during the day, feeding on a was absorbed (Frost and Kipling 1967, Inskip wide variety of prey from invertebrates to 1982). The juveniles grow rapidly, increasing (Polyak 1957, Carlander and Cleary 1949, their size and activity, and the shelter provided Casselman and Lewis 1996, Craig 2008). As by the vegetative cover helps enhance survival opportunistic feeders E. lucius will feed on prey (Casselman and Lewis 1996). As they grow, that is seasonally abundant, although the size of juveniles move to more floating and submergent their prey is limited by both their size and the vegetation, rather than the emergent vegetation size of their prey (Craig 2008). They can preferred by fry, but remain in shallow waters consume a wide range of prey sizes, but have (Casselman and Lewis 1996, Craig 2008). also been shown to be size-selective predators (Nilsson and Bronmark 2000, Craig 2008). spawning groups, usually consisting of one Although they can be cannibalistic, this has not female and either one or several males. 5-60 been shown to comprise a large portion of their eggs are released at any one spot, where they are diet (Frost 1954, Lawler 1965, Mann 1976). then fertilized by males (Svardson 1949, Clark Aquatic vegetation is particularly important for 1950). The gametes are broadcasted, with no feeding as these fish utilize and ‘ambush’ style parental care provided post-spawning (Eddy and of (Inskip 1982, Casselman and Lewis Underhill 1974, Inskip 1982). Any one 1996). Intermediate vegetation densities have spawning group can release gametes over a large been associated with optimum predation area of spawning habitat (Koshinsky 1979). efficiency (Craig and Black 1986), and calm, Franklin and Smith (1963) found the number of clear waters provide better visibility associated eggs produced to be highly dependent on female with more efficient prey capture (Craig 2008). body size, described by the equation y = 4401.4x Fry begin feeding once they reach a length of – 66245, with y equal to the number of eggs approximately 10-12 mm in length, about 10 produced, and x as the total length of the fish in days after hatching (Franklin and Smith 1963). inches. Females weighing 0.75 lbs may produce They initially feed on zooplankton, but soon from 9,000 to 10,000 eggs, while a female begin to feed on aquatic larvae and fish, weighing 10 lbs may produce 100,000 eggs marking the start of piscivory very early in their (Lagler 1956). life (Hunt and Carbine 1951, Frost 1954, Inskip 1982). Within 4-5 weeks after hatching, at a Environmental optima and tolerances length of approximately 50-60 mm, their diet is Northern pike are a cool water species, comprised mostly of fish, and fry as small as 21 but have a wide range of environmental mm have been shown to be cannibalistic (Hunt tolerances including water temperature, and Carbine 1951). As they continue to grow, dissolved oxygen concentration, and water their prey is predominantly fish, although they clarity, which, in part, can be attributed to their have been known to prey on , waterfowl success as an (Casselman 1978, and even small (Frost 1954, Lagler Steinberg 1992, Casselman and Lewis 1996). 1956, Seaburg and Moyle 1964, Lawler 1965, These optima and tolerances, however, vary Mann 1976, Inskip 1982). among life-cycle stages (Inskip 1982). E. lucius embryos are tolerant of temperatures Reproductive strategies up to 19°C (Siefert et al. 1973), with maximum E. lucius is an iteroparous species, hatching success occurring at temperatures from undergoing multiple reproductive events, with a 9-15°C and severe mortality at temperatures relatively high fecundity. These fish form near 5°C (Hassler 1970). Dissolved oxygen concentrations of 4.5 mg/L is optimal for shown no apparent stress at temperatures as low embryo development, while concentrations of as 0.1°C prior to freezing in a shallow lake 3.2 mg/L or less result in high embryo mortality (Casselman 1978). Despite these wide (Siefert et al. 1973). Embryos are particularly temperature tolerances, sudden drops in sensitive to high rates of siltation (≥1 mm/day) temperature can be lethal (Ash et al. 1974, (Hassler 1970), and exposure to hydrogen Inskip 1982). A significant decrease in feeding sulfide of concentrations greater than 0.014- has been observed in adults exposed to dissolved 0.018 ppm for 96 hours decreases hatching oxygen concentrations around 2-3 mg/L, and success (Adelman and Smith 1970a). feeding has been shown to stop altogether at Fry survival and growth is greatest at concentrations less than 2 mg/L (Adelman and temperatures from 18.0-20.8°C, with poor Smith 1970b, Casselman and Lewis 1996). E. survival at temperatures lower than 5.8°C and lucius can inhabit areas with pHs ranging from higher than 25.6°C (Lillelund 1966, Hokanson et 6.1-8.6 (Margenau et al. 1998), and can tolerate al. 1973). Hydrogen sulfide concentrations some salinity, having been found frequently in greater than 0.004-0.006 ppm for 96 hours the (Crossman 1979). significantly decreased survival of yolk sac fro (Adelman and Smith 1970a). Biotic associations Juvenile E. lucius reach maximum growth rates Biotic associations of E. lucius vary at temperatures ranging from 19-21°C, with across the native and introduced range of the significantly decreased survival at temperatures species, although there are numerous pathogens lower than 3°C and above 28°C (Casselman and parasites that can be associated with this 1978). Growth rates were hindered at dissolved species. One notable ectocommensal organism oxygen concentrations below 7 ppm, and very associated with E. lucius is the ciliate low juvenile survival occurred at concentrations Capriniana piscium, also known as Trichophyra below 3 ppm (Adelman and Smith 1970b). piscium. C. piscium attaches to the lamellar Feeding ceased at less than 2 ppm and no fish at epithelia of the gill surface of E. lucius using dissolved oxygen concentrations of 1 ppm microfobrils that connect to the host cell survived more than 20 hours in a study by Petit membrane (Lom 1971, Hofer et al. 2005; Figure (1973). 2). It was previously thought that high densities Adults have the greatest environmental of these organisms could cause tissue damage in tolerances of the life-cycle stages, with a the host, however, there is no evidence of C. maximum temperature tolerance of over 30°C piscium feeding on the host cells (Lom and (Ridenhour 1957). Optimum growth occurs at Dykova 1992). Instead, this commensal uses its approximately 20-21°C, but adult E. lucius have tentacles to feed on ciliates that are in the water populations in 41 states, including , Oregon and (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 , Idaho, and the 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).

Figure 2: C. piscium in the interlamellar space of fish gills. The tentacles protrude from the gill surface where History of invasiveness they can capture prey (Hofer et al. 2005). Esox lucius has a long history of that passes through the lamellae (Lom introduction and subsequent invasions, both in 1971, Dovgal 2002, Hofer et al. 2005). the United States and elsewhere. This species is historically absent from Mediterranean France, 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 basins as well as , , and (Page and Burr 1991), and the South River Drainage in Montana (Holton and Johnson 1996).

However, E. lucius has been Figure 3: Native and invaded ranges of E. lucius in the United States (US reported to have non-native Geological Survey 2011). 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).

into the Hudson River Basin, where it central , southern and western Greece, and subsequently spread to the lower Hudson River northern Scotland, but has been widely by 1976 (Mills et al. 1997). Widespread translocated throughout (Kottelat and stocking of E. lucius in the Chesapeake Basin Freyhof 2007), introduced to Spain, Portugal, began in the 1960’s in Pennsylvania, followed and (Welcomme 1988), among other by stocking in and Virginia locations. E. lucius has also been introduced to (Denoncourt et al. 1975). In 1992, 4000 E. Algeria, Ethiopia, Madagascar, , lucius fingerlings were released in the District of Tunisia, and Uganda (Welcomme 1988, Lever Columbia, although the survival of these fishes 1996). is unknown (Christmas et al. 2000). In As an important fish, the introduction , E. lucius was introduced to the Elk- history of E. lucius outside of its native range in head Reservoir of the Yampa River drainage in the United States dates back to the 1800’s. The 1977, where they subsequently invaded the first recorded introduction of Esox lucius in the Green River basin of Colorado and in 1981 United States outside of its native range was in (Wick et al. 1985), with similar introduction the 1840’s when the United States Fish histories for other states with established E. Commission intentionally introduced the fish lucius populations. E. lucius was first introduced to the Pacific for those stocking the water body, but this Northwest in the early 1950’s (Brown 1971) and unregulated introduction of E. lucius can play a now occurs throughout the Columbia River large role in facilitating the spread of this basin. It was illegally stocked into Coeur species (McMahon and Bennett 1996). d'Alene Lake, Idaho, in the early 1970’s (Rich In the Pacific Northwest, one of the initial 1993), where it then spread into several other introductions of E. lucius was via illegal lowland lakes in northern Idaho (McMahon and stocking with Coeur d’Alene Lake, Idaho (Rich Bennett 1996). Although E. lucius is native to 1993), resulting in the subsequent spread of this Montana in the drainage, it species across northern Idaho. E. lucius has now spread throughout the state (DosSantos populations in Washington are a result of illegal 1991), and has also spread to Idaho, Washington stocking in the Flathead, Bitterroot and Clark and Oregon. Fork River systems in Montana. These fish then migrated into Lake Pend Orielle, through Idaho Invasion process by way of the Pend Orielle River, into Washington (Washington Department of Fish Pathways, vectors and routes of introduction and Wildlife). In the past few years, these fish The primary introduction pathway of Esox have spread from Boundary Reservoir into the lucius is the intentional stocking of the fish for Columbia River, and can now be found in recreational purposes (Fuller 2011). As an Oregon as well, most likely though downstream important sport fish, E. lucius has been migration in the Columbia River (McMahon and intentionally introduced across the country Bennett 1996). initially by the United States Fish Commission, and later by various state agencies, to stimulate Factors influencing establishment and spread opportunities in various parts of the The establishment and spread of a species country (Jenkins and Burkhead 1993; Scott and is determined by the environmental tolerances of Crossman 1973). Intentional introductions still that species, as well as certain life-history occur due to public pressures for fishing characteristics. E. lucius can withstand a wide opportunities, despite the risks associated with range of environmental conditions (Casselman introductions (McMahon and Bennett 1996). 1978, Steinberg 1992, Casselman and Lewis Illegal stocking, or bait-bucket transfer, also 1996), increasing the likelihood of establishment frequently occurs, in which E. lucius are and spread of this species due to the fact that intentionally introduced to an ecosystem without there is a large amount of habitat with tolerable authorization. This is typically done to promote environmental conditions available. E. lucius is fishing opportunities in the recipient ecosystem also a relatively fecund species (Casselman and Lewis 1996), which may allow for rapid lucius populations can not only severely establishment of populations and subsequent decrease prey fish abundances (He and Kitchell spread to new areas. 1990), but also create undesirable fisheries due The main factor that may restrict the ability of E. to their small size. If E. lucius populations were lucius to establish and spread, however, is the left unchecked, they could cause a loss of availability of shallow habitat with submerged revenue from sport fisheries as well as have vegetation (DosSantos 1991) vital in spawning drastic impacts on native fish populations as well as adult foraging, as well as the presence (Washington Department of Fish and Wildlife). of suitable fluctuation of water levels during the The effects that E. lucius can have on native spawning period (see life-cycle section) (Inskip fishes have very important implications, 1982). The nature of these specialized habitat especially when considering the native fishes of requirements therefore serve to limit the the Pacific Northwest. One of the main concerns distribution and likelihood of spread (Jones associated with the spread of E. lucius is the 1990). Because these fish are highly predatory, impact this species can have on local an abundant prey base in the recipient populations (McMahon and Bennett 1996). E. community is also necessary to support E. lucius lucius have been shown to have drastic negative populations (McMahon and Bennett 1996), impacts on salmon populations as they feed on which may further constrain the amount of salmon smolts migrating to sea (Larson 1985, suitable habitat available for colonization. Petrvozvanskiy et al. 1988) and these fish have been associated with the extinction of local Potential ecological and/or economic impacts salmonid populations (Bystrom et al. 2007, There are many potential ecological and Spens 2007, Spens and Ball 2008), making their economic impacts associated with the invasion a serious threat. introduction of E. lucius outside of its native While the introduction of E. lucius threatens to range. As a keystone piscivore, this fish can cause serious declines in a popular Pacific shape the composition, abundance and Northwest sport fish, E. lucius in itself is also an distribution of fish communities (Craig 2008), important sport fish, and there are strong which has important implications when economic benefits associated with the considering the native fish communities, as well introduction of this species. Stocking of these as sport fisheries. In places where E. lucius is fish can generate popular sport fisheries, which overpopulated, there is a resultant overfeeding can create important revenue that enhances local on their prey base, which impedes the growth of economies (McMahon and Bennett 1996). these fish. Stunted growth, however, does not However, this economic benefit can to lead to an result in lower reproduction, so overabundant E. increase in the frequency of illegal stocking (Vashro 1990, 1995), further contributing to the common strategies for fish population continued spread of E. lucius and the harmful suppression and removal, although they tend to effects that can follow. be costly and/or labor intensive, with tradeoffs associated with each strategy (CDF&G et al. Management strategies and control methods 2006). An important management strategy in There are several different management preventing the spread of E. lucius is regulation strategies and control methods for Esox lucius of illegal introductions. Many states have laws populations, the most effective of which, that prevent the transport of live fish from a however, is prevention. Once established, these waterbody (e.g., Idaho, Oregon, and western fish can spread to neighboring habitats, Montana), but there is strong opposition from drastically affecting the recipient biotic the public and it is difficult to closely manage communities (He and Kitchell 1990, Craig the actions of individuals stocking fish illegally 2008), making a preemptive response the best (McMahon and Bennett 1996). In Montana, the approach. One of the main prevention strategies legislature stiffened penalties associated with the is education, allowing for an early-warning illegal stocking of fish, such as fines, suspension system for new introductions in which a quick of fishing privileges, and liability for cost of response can be enacted, as well as increasing restoring a fishery, and they have even offered awareness of the impacts of E. lucius, hopefully rewards for reporting such activity (McMahon deterring the intentional introduction of the and Bennett 1996). Following the actions of the species. Montana legislature in creating public incentive However, in the cases where introduction has seems to be a good place to start in terms of already occurred, primary strategies for the finding better ways to raise awareness and control of E. lucius include the suppression of E. prevent the introduction of invasive species. lucius populations, the prevention of spread to other waterways, and removal of as many Literature cited organisms as possible using a variety of methods. Prevention of spread to other Adelman, I.R., and Smith, L.L. 1970a. Effect of waterways is particularly important in hydrogen sulfide on northern pike eggs and attempting to control E. lucius populations, sac fry. Trans. Am. Fish. Soc. 99:501-509. because by limiting their access to habitat it constrains their ability to spread and establish Adelman, I.R., and Smith, L.L. 1970b. Effect of subsequent populations. Electrofishing, trapping oxygen on growth and food conversion and the use of rotenone, a fish toxicant, are efficiency of northern pike. Prog. Fish-Cult. 32:93-96. Soc. Spec. Publ. 11: 114-128.

Ash, G.R., Chymko, N.R., and Gallup, D.N. Casselman, J.M. and Lewis, C.A. 1996. Habitat 1974. Fish kill due to "cold shock" in Lake requirements of northern pike (Esox lucius). Wabamun, . J. Fish. Res. Board Canadian Journal of Fisheries and Aquatic Can. 31: 1822-1824. Sciences 53(Suppl. 1): 161–174.

Brown, C. J. D. 1971. Fishes of Montana. Big Christmas, J., Eades, R., Cincotta, D., Shiels, Sky Books, Bozeman, MT. A., Miller, R., Siemien, J., Sinnott, T., and Fuller, P. 1998 History, management, and Buss, K., and Miller, J. 1961. The age and status of introduced fishes in the growth of northern pike. Penn. Angler Chesapeake Bay basin. Proceedings of 30(3): 6-7. Conservation of Biological Diversity: A Key to the Restoration of the Chesapeake Bystrom, P., Karlsson, J., Nilsson, P., Ask, J., Bay Ecosystem and Beyond. pp. 97-116. and Olofsson, F. 2007. Substitution of top predators: effects of pike invasion in a Clark, C.F. 1950. Observations on the spawning subarctic lake. Freshw. Biol. 52: 1271– habits of northern pike, Esox lucius, in 1280. northwestern . Copeia 1950(4): 258- 288. Department of Fish and Game, U.S. Department of Agriculture, and the U.S. Craig, J.F. 2008. A short review of pike ecology. Forest Service. 2006. Lake Davis pike Hydrobiologia 601: 5-16. eradication project. Draft EIS/EIR. http://www.dfg.ca.gov/northernpike/EIR- Craig, R.A., and Black, R.M. 1986. Nursery EIS/index.html. habitat of in southern Georgian Bay, Lake Huron, . Am. Carlander, K.D., and Cleary, R.E. 1949. The Fish. Soc. Spec. Publ. 15: 79–86. daily activity pattern of some freshwater fishes. Am. Midi. Nat. 41: 447-452. Crossman, E.J. 1978. and distribution of North American esocids. Casselman, J.M. 1978. Effects of environmental Am. Fish. Soc. Spec. Publ. 11: 13-26. factors on growth, survival, and exploitation of northern pike. Am. Fish. Denoncourt, R.F., Robbins, T.W. and Hesser, R. 1975. Recent introductions and Frost, W.E. 1954. The food of pike, Esox lucius reintroductions to the Pennsylvania fish L., in Windermere. J. Anim. Ecol. 23: 339- fauna of the Susquehanna River drainage 360. above Conowingo Dam. Proceedings of the Pennsylvania Academy of Science 49: 57- Frost, W.E., and Kipling, C. 1967. A study of 58. reproduction, early life, weight-length relationship and growth of pike, Esox lucius Dickson, T. 2003. Breakthrough at Milltown L., in Windermere. J. Anim. Ecol . 36: 651- Damn. The Magazine of Montana Fish, 693. Wildlife, and Parks. May/June 2003 Issue. Hassler, T.J. 1970. Environmental influences on DosSantos, J. M. 1991. Ecology of a riverine early development and year-class strength pike population. Pages 155-159 in J. L. of northern pike in Lakes Oahe and Sharpe, Cooper, ed. Warmwater Fisheries . Trans. Am. Fish. Soc. 99: Symposium I. U.S. For. Serv. Gen. Tech. 369-375. Rep. RM-207. He, X., and Kitchell, J.F. 1990. Direct and Dovgal, I.V. 2002. Evolution, phylogeny and indirect effects of predation on a fish classification of suctoria (Celiphora). community: a whole lake experiment. Protistol. 2: 194 – 270. Transactions of the American Fisheries Society 119: 825-835 Eddy, S., and Underhill, J.C. 1974. Northern fishes. Univ. Minn. Press, Minneapolis, Hofer, R., Salvenmoser, W., and Fried, J. 2005. MN. 414 pp. Population dynamics of Capriniana piscium (Ciliophora, Suctoria) on the gill Forney, J.L. 1968. Production of young northern surface of Arctic char (Salvelinus alpinus) pike in a regulated marsh. N.Y. Fish Game from high mountain lakes. Arch. Hydrobiol J. 15:143-154. 162(1): 99-109.

Franklin, D.R., and Smith, L.L. 1960. Notes on Hokanson, K.E.F., McCormick, J.H., and Jones, the early growth and allometry of the B.R. 1973. Temperature requirements for northernpike, Esox lucius L. Copeia embryos and larvae of the northern pike, 1960(2): 143-144. Esox lucius (Linnaeus). Trans. Am. Fish. Soc. 102: 89-100. northern pike population. Saskatchewan Fish. Lab. Tech. Rep. 79-80. Dept. Tourism Holton, G.D. and Johnson, H.E. 1996. A field Renewable Resour., Saskatoon, guide to Montana fishes, second edition. Sakatchewan, Canada. 303 pp. Montana Department of Fish, Wildlife and Parks. Helena, MT. 104pp. Kottelat, M. and Freyhof , J. 2007 Handbook of European freshwater fishes. Publications Hunt, B.P. and Carbine, W.F. 1950. Food of Kottelat, Cornol, Switzerland. 646 p. young pike, Esox lucius, L., and associated fishes in Peterson's ditches, Houghton Lagler, K.F. 1956. The pike, Esox lucius Lake, . Trans. Am. Fish. Soc. 80: Linnaeus, in relation to waterfowl, Seney 67-83. National Wildlife Refuge, Michigan. J. Wildl. Manage. 20: 114-124. Inskip, P.D. 1982. Habitat suitability index models: northern pike. U.S. Fish Wildl. Larson, K. 1985. The food of northern pike Serv. FWS/OBS–82/10.17. Esox lucius in streams. Medd. Danm. Fiskeri-og Havunders. (NySer.) 4: 271-326. Jenkins, R. E., and Burkhead. N.M. 1994. Freshwater fishes of Virginia. American Lawler, G.H. 1965. The food of pike Esox Fisheries Society, Bethesda, MD. lucius, in Heming Lake . J. Fish. Res. Bd. Canada 22:1357-1377. Johnson, F.H. 1957. Northern pike year-class strength and spring water levels. Trans. Lever, C. 1996. Naturalized fishes of the Am. Fish. Soc. 86: 285-293. world.. Academic Press, California, USA. 408 p. Jones, T. S. 1990. Floodplain distribution of fishes of the Bitterroot River, with Lillelund, V.K. 1966. Versuche zur erbrutung emphasis on introduced populations of der Eier vom Hecht, Exos lucius L., in northern pike. Master's thesis. University of Abhängigkeit von Temperatur und Licht. Montana, Missoula. Arch. Fishereiwiss. 17: 95-113. (English summary) Koshinsky, G.D. 1979. Northern pike at Lac La Ronge. Part 1. Biology of northern pike. Lom, J. 1971. Trichophrya piscium: a pathogen Part 2. Dynamics and exploitation of the or an ectocommensal? An ultrastructural study. Folia Parasitologica (Praha) 18: 197– spawning habitat and early stage mortality 205. of Northern pike (Esox lucius) in a large system: the St. Lawrence River between Lom, J. and Dykovà, I. 1992. Protozoan 1960 and 2000. Hydrobiologia 601: 55–69. parasites of fishes. Development in Aquaculture and Fisheries Sciences 26: 250 Morrow, J.E. 1980. The freshwater fishes of – 252. Alaska. University of. B.C. Resources Ecology Library. 248p. Mann, R.H.K. 1976. Observations on the age, growth, reproduction and food of the pike Nilsson, P.A. and Bronmark, C. 2000. Prey Esox lucius (L.) in two rivers in southern vulnerability to a gape-size limited England. J. Fish Biol. 8: 179-197. predator: behavioural and morphological impacts on northern pike piscivory. Oikos Margenau, T.L., Rasmussen, P.W., and Kampa, 88: 539–546. J.M. 1998. Factors affecting growth of northern pike in small northern Page, L.M., and Burr, B.M. 1991. A field guide lakes. North American Journal of Fisheries to freshwater fishes of north Management 18: 625-639. of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin McMahon, T.E., and Bennett, D.H. 1996. Company, Boston, MA. and northern pike: boost or bane to northwest fisheries? Fisheries 21(8): 6-13. Petit, G.D. 1973. Effects of dissolved oxygen on survival and behavior of selected fishes of Miller, R. B., and Kennedy, W.A. 1948. Pike western Lake Erie. Bull. Ohio Biol. Surv. (Esox lucius) from four northern Canadian New Ser. 4: 1-76. lakes. J. Fish. Res. Board Can. 7: 176-189. Petrozvanskiy, V.Y., Bugaev, V.F., Shustov, Mills, E.L., Scheuerell, M.D., Carlton, J.T. and Y.A., and Shchurov, I.L. 1988. Some Strayer, D. 1997. Biological invasions in ecological characteristics of northern pike, the Hudson River: an inventory and (Esox lucius), of the Keret’, a salmon river historical analysis. Trade paperback, in the White Sea basin. Journal of University of State of . 51 pp. Ichthyology, Volume 28: 136-140.

Mingelbier, M., Brodeur, P., and Morin, J. 2008. Polyak, S.L. 1957. The visual system. Spatially explicit model predicting the University of Chicago Press. 1390 pp. Fish. Soc. 93: 269-285.

Priegel, G.R., and Krohn. D.C. 1975. Siefert, R.E., Spoor, W.A. and Syrett, R.F. 1973. Characteristics of a northern pike spawning Effects of reduced oxygen concentrations population. Wis. Dept. Nat. Resour. Tech. on northern pike (Esox lucius) embryos and Bull. 86. 18 pp. larvae. J. Fish. Res. Board Can. 30: 849- 852. Rich, B. A. 1993. Population dynamics, food habits, movement and habitat use of Spens, J. 2007. Can historical names and fishers’ northern pike in the Coeur d'Alene River knowledge help to reconstruct the system. Master's thesis. University of distribution of fish populations in lakes? In Idaho, Moscow. Fishers’ knowledge in fisheries science and management. Edited by N. Haggan, B. Ridenhour, R.L. 1957. Northern pike, Esox Neis, and I. Baird. Coastal Management lucius L. , population of Clear Lake, . Sourcebooks 4. Chap. 16. UNESCO, Paris, Iowa State Coll. J. Sei. 32(1): 1-18. France. pp. 329–349.

Schryer, F., Ebert, V., and Dowlin, L. 1971. Spens, J., and Ball, J.P. 2008. Salmonid or Statewide fisheries surveys. Determination nonsalmonid lakes: predicting the fate of of conditions under which northern pike northern boreal fish communities with spawn naturally in reservoirs. hierarchical filters relating to a keystone Dingell-Johnson Proj. F-15-R-6, Job C-3. piscivore. Can. J. Fish. Aquat. Sci. 65: Final Res. Rep., Kan. Forestry, Fish Game 1945–1955. Comm. 37 pp. Sternberg, D.1992. Northern Pike and Muskie. Scott, W. B. and Crossman, E.J. 1973. CY DeCrosse Inc. Freshwater Fishes of Canada. Department of Fisheries and Oceans Scientific Svardson, G. 1949. Notes on spawning habits of Information and Publications Branch. Leuciscus erythrophthalmus (L.), Abramis Ottawa, Canada. 966 pp. brama (L.). and Esox lucius L. Fish. Board Sweden, Inst. Freshwater Res., Seaburg, K.G., and Moyle, J.B. 1964. Feeding Drottningholm 29: 102-107. habits, digestive rates and growth of some warmwater fishes. Trans. Am. Vashro, J. 1990. Illegal aliens. Montana Outdoors 21(4): 35-37. Washington Department of Fish and Wildife http://wdfw.wa.gov/ais/esox_lucius/ Vashro, J. 1995. The "bucket brigade" is ruining our fisheries. Montana Outdoors 26(5): 34- Expert contact information in PNW 37. David H. Bennett Welcomme, R. L. 1988. International Fish and Wildlife Resources Department Introductions of Inland Aquatic Species. University of Idaho, Moscow, ID 83844-1136 FAO Fisheries Technical Paper No. 294. [email protected] Food and Agriculture Organization of the United Nations, Rome, Italy. 318pp. Thomas E. McMahon Biology Department, Fish and Wildlife Program Wick, E.J., and Hawkins, J.A. 1989. Colorado Montana State University, Bozeman, MT 59717- squawfish winter habitat study, Yampa 0346 River, Colorado, 1986-1988. Final report. [email protected] Contribution 43, Larval Fish Laboratory, Colorado State University. Fort Collins, Deane Osterman Colorado. 96 pp. Executive Director for Natural Resources Kalispel Tribe Other key sources of information and bibliog Kalispel Tribal Headquarters raphies P.O. Box 39 Usk, WA 99180 California Department of Fish and Game Phone: (509) 445-1147 http://www.dfg.ca.gov/lakedavis/biology.html Fax: (509) 445-1705

FishBase Current research and management efforts http://www.fishbase.org/summary/Esox- lucius.html Currently, there are numerous ongoing efforts to control the spread of Esox lucius, with USGS Nonindigenous Aquatic Species a focus on eradicating populations that have Database. Pam Fuller. 2011. Esox lucius. been introduced illegally. In Montana, E. lucius http://nas.er.usgs.gov/queries/FactSheet.aspx?Sp removal programs have been implemented in the eciesID=676 Revision Date: 6/21/2010 Milltown Dam Reservoir to help restore native cutthroat and bull trout. The dam impedes salmonid migration causing them to concentrate the Pend Orielle River. Surveys are being in the reservoirs, providing easy prey for the E. conducted to determine the relative abundances lucius that reside there (Dickson 2003). The of E. lucius, the structure of the overall fish Montana Department of Fish, Wildlife, and community, and the timing of E. lucius Parks have temporarily lowered the later levels spawning activities. The WDFW is attempting to of the reservoir each year to kill yearling E. learn more about the impacts of E. lucius on lucius that occupy the back channels, resulting native salmonid populations, using events that in reduced fish populations, although the process occurred in south-central Alaskan watersheds as is labor intensive. Montana has also recruited a model to attempt to prevent similar damage to angler organizations to help control E. lucius Washington salmonid populations, and has populations, as well as prevent illegal proposed to remove E. lucius’s classification as introductions (McMahon and Bennett 1996). a , causing it to be listed solely as a The California Department of Fish and Game prohibited species. (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

Top View