Northern pike

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Northern pike (Esox lucius)
Northern pike
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Superorder: Protacanthopterygii
Order: Esociformes
Family: Esocidae
Genus: Esox
Species: E. lucius
Binomial name
Esox lucius
Linnaeus, 1758

The northern pike (Esox lucius), known simply as a pike in Britain, Ireland, Canada and most parts of the USA, also called jackfish or simply "Northern" in the Upper Midwest of the USA), is a species of carnivorous fish of the genus Esox (the pikes). They are typical of brackish and freshwaters of the northern hemisphere (i.e. holarctic in distribution). Pike grow to a relatively large size; lengths of 150 centimetres (59 in) and weights of 25 kilograms (55 lb) are not unheard of. The average length is about 70–120 cm (28-47 inches). The heaviest specimen known so far was caught in 1983 at an abandoned stone quarry in Germany, where the species is known as a Hecht. She (the majority of all pikes over 8 kg or 18 lb are females) was 147 cm (58 in) long and weighed 31 kg (68 lb). The longest pike ever recorded and confirmed was 152 cm (60 in) long and weighed 28 kg (62 lb). A pike of 60.5 inches (154 cm) was caught and released in May 2004 in Apisko Lake, Manitoba. Historic reports of giant pike, caught in nets in Ireland in the late 19th century, of 41–42 kg (90–93 lb) with a length of 173–175 cm (67-68 inches), were researched by Fred Buller and published in "The Domesday Book of Mammoth Pike". Neither Britain nor Ireland has managed to produce much in the way of giant pike in the last 50 years and as a result there is substantial doubt surrounding those earlier claims. Currently, the IGFA recognizes a 25 kg (55 lb) pike caught by Lothar Louis in Lake of Grefeern, Germany, on October 16, 1986 as the all-tackle world record northern pike.

Etymology[edit]

Northern pike in the Aquarium Dubuisson (fr)
Esox lucius skull

The northern pike gets its name from its resemblance to the pole-weapon known as the pike (from the Middle English for pointed). The genus name, Esox, comes from the Greek and Celtic for "big fish" and "salmon" (see Esox: Name). Various other unofficial trivial names are: American pike, common pike, great northern pike, Great Lakes pike, grass pike, snot rocket, slough shark, snake, slimer, slough snake, northern, gators (due a head similar in shape to that of an alligator), jack, jackfish, Sharptooth McGraw, Mr. Toothy and other such names as Long head and Pointy nose. Numerous other names can be found in Field Museum Zool. Leaflet Number 9.

Description[edit]

Northern pike in public aquarium in Kotka, Finland
Northern pike in the Straussee at Strausberg

Northern pike are most often olive green, shading from yellow to white along the belly. The flank is marked with short, light bar-like spots and there are a few to many dark spots on the fins. Sometimes the fins are reddish. Younger pike have yellow stripes along a green body, later the stripes divide into light spots and the body turns from green to olive green. The lower half of the gill cover lacks scales and they have large sensory pores on their head and on the underside of the lower jaw which are part of the lateral line system. Unlike the similar-looking and closely related muskellunge, the northern pike has light markings on a dark body background and fewer than six sensory pores on the underside of each side of the lower jaw.

Drawing of Northern pike

A hybrid between northern pike and muskellunge is known as a Tiger Muskellunge (Esox masquinongy × lucius or Esox lucius × masquinongy,[1] depending on the sex of each of the contributing species). In the hybrids, the males are invariably sterile, while females are often fertile, and may back-cross with the parent species.[2] Another form of northern pike, the silver pike, is not a subspecies but rather a mutation that occurs in scattered populations. Silver pike, sometimes called silver muskellunge, lack the rows of spots and appear silver, white, or silvery-blue in color.[3] When ill, Silver pike have been known to display a somewhat purplish hue; long illness is also the most common cause of male sterility.

In Italy, the newly identified species Esox flaviae ("southern pike") was long thought to be a color variation of the northern pike, but was in 2011 announced to be a species of its own.[4]

Length and weight[edit]

In addition to the stats earlier presented, (see above), Northern pike in North America seldom reach the size of their European counterparts; one of the largest specimens known was a 21 kg (46 lb) specimen from New York state. It was caught in Great Sacandaga Lake on 15 September 1940 by Peter Dubuc. There are reports of far larger pike, but these are either misidentifications of the pike's larger relative the muskellunge, or simply have not been properly documented and belong in the realm of legend.

Northern pike weight length graph.jpg

As northern pike grow longer, they increase in weight. The relationship between length and weight is not linear. The relationship between total length (L, in inches) and total weight (W, in pounds) for nearly all species of fish can be expressed by an equation of the form:

W = cL^b\!\,

Invariably, b is close to 3.0 for all species, and c is a constant that varies among species. For northern pike, b = 3.096 and c = 0.000180. (c=7.089 enables you to put in length in meters and weight in kg)[5]

The relationship described in this section suggests that a 20-inch (510 mm) northern pike will weigh about 2 lb (0.91 kg), while a 26-inch (660 mm) northern pike will weigh about 4 lb (1.8 kg).

Behavior[edit]

Aggressiveness[edit]

The Northern pike is a relatively aggressive species, especially with regards to feeding and other such activities. For example, when food rations are poor, cannibalism develops, starting around five weeks in a small percent of populations.[6] This cannibalism occurs when the ratio of predator to prey is 2 to 1.[6] One can expect this because when food is scarce, Northern pike fight for survival, such as turning on smaller pike in order to feed. We see this in other species such as tiger salamanders. Usually, pike have tendencies to feed upon smaller fish, such as the Banded killifish. However, when pike exceed 700mm, they will feed on larger fish.[7] As one can probably assume, these pike are the ones most likely to develop cannibalistic traits.

Because of cannibalism when food is short, pikes suffer a fairly high young mortality rate. [8] Cannibalism is more prevalent in cool summers as the upcoming pikes have slow growth rate in that season and might not be able to reach a size that deters the larger pikes. Cannibalism is likely to arise in low growth and low food conditions.[8] It should be noted that pike do not discriminate well between siblings, and as such, cannibalism between siblings is likely. However, further research is needed to determine if pike have a preference to not cannibalize relatives like other cannibalistic species.

Aggressiveness also arises from a need of space.[9] We see that young pike have a tendency to have their food robbed by larger pike.[9] The reason why pike are aggressive if not given enough space is because pike are territorial species.[10] They undergo a form of foraging known as Sit and Wait. Unlike species such as perch, pike will undergo bursts of energy instead of actively chasing down prey. As such, there is a fair amount of inactive time until they find prey. We see from experiments that hunting efficiency decreases with competition.[10] The larger the pike, the larger the area that is controlled by that particular pike. In addition, there is a preference from larger pike. There is an inverse relation to vegetation density and pike size, which is due to the possibility of cannibalism from the largest pike.[11] This makes sense as the smaller pike needs more vegetation to avoid being eaten. Large pike do not have this worry and can afford the luxury of having a large line of sight to work with. They prefer a tree structure habitat.[11]

Physical behavioral traits[edit]

Pike are capable of “fast start” movements, which are sudden high energy-bursts of unsteady swimming.[12] Many other aquatic fish exhibit this movement as well. The reason that most fish utilize this mechanism is to avoid life-threatening situations for most fish, similar to an adrenaline rush. For the pike however, it is a tool used in order to capture prey from their sedentary position. They flash out in such bursts and capture their prey. These fast starts terminate when the pike has reached terminal velocity.[12] During such motions, pike make S conformations while swimming at high rates. To decelerate, they, simply make a C conformation, exponentially slowing down their speed so that they can “stop”.[12] An interesting behavioral trait that pike have is that they have short digestion times and long feeding periods.[7] It makes sense in the fact that they can undergo many of these fast-bursts in order to collect as much prey as they can. For pike, their time of least activity is during the night.[10]

Reproduction/Habitat[edit]

Pike have a strong homing behavior;[11] they are privy to inhabit certain areas by nature. During the summer, pike tend to group closer to vegetation than during the winter.[13] The exact reason is not clear, but it is very likely this is a result of foraging or possibly reproductive needs to safeguard young. Pike diel rhythm changes significantly over the year.[14] We see that on sunny days pike stay closer to the shallow shore. On windy days, they are further from shore.[15] When close the shore, pike have a preference for shallow vegetated areas.[15] In an experiment done, scientists have found that pike are more stationary in reservoirs than lakes.[16] A possibility is that lakes have more prey to feed upon, or possibly in reservoirs prey will ultimately cross paths with the pike. As such, this could be a form of energy conservation. Pike prefer to breed in the spring.[9] They also mature in around two years before they are physically capable of breeding. Pike also have a tendency to lay a large amount of eggs.[9] A likely explanation for such actions are to produce as many surviving offspring as possible as many most likely die early in life. As such, to ensure the greatest genetic success, pike will produce a large amount of offspring. In females, the gonads enlarge when it is time to shed her eggs.[9] However, after they are shed, these eggs will not spawn if the water is below 6 degrees Celsius.[9] Male pike arrive to the breeding grounds before females do. In addition, the males will stay after the spawning is finished.[9] We see this in many fish. Male parental care in fish is not uncommon, so such behavior is to be expected. In pike, parental stock is vital for pike success.[17] In addition, we see that mortality rates do indeed change from high to low with more eggs that are laid. In fact, it is a tenfold difference.[17] As such, such a behavior has been developed through evolutionary trials. For breeding, the more stable the water, the greater the fitness of the pike.[18] We see this as mortality results from toxic concentrations of iron or rapid temperature changes.[18] We see that adult abundance and the strength of the resulting year classes are not related. It is based upon two points of development: one during embryo stage between fertilization and closure of the blastophore and the second is between hatching and the termination of the alevin stage.[18]

Ecology[edit]

Habitat[edit]

Pike take big prey and are not very particular.

Pike are found in sluggish streams and shallow, weedy places in lakes, as well as in cold, clear, rocky waters. Pike are typical ambush predators; they lie in wait for prey, holding perfectly still for long periods and then exhibit remarkable acceleration as they strike. In short, they will inhabit any water body that contains fish, but suitable places for spawning are essential for their numbers. Because of their cannibalistic nature, young pike need places where they can take shelter between plants so they are not eaten. In both cases it comes down to a rich submersible vegetation nearby. Pike are seldom found in brackish water, except for the Baltic Sea area. Pike are known to prefer water with less turbidity but that is probably related to their dependence on the presence of submersible vegetation and not to their being a sight hunter.

Reproduction[edit]

Pike are known to spawn in spring when the water temperature first reaches 9 °C (48 °F).[19] The males are first at the spawning grounds preceding the females by a few weeks. The larger females tend to arrive earlier than the smaller ones. A female may be followed by several smaller males. When a pair starts slowing down the male will put his tail under the female's body and release its sperm that is mixed with the eggs due to the tail movement. The spawning consists of a great number of these moves several times a minute and going on for a few hours a day. Every move between 5 and 60 eggs are laid. A female can continue the mating for three days in a row. After the mating the males tend to stay in the area for a few extra weeks.

The color of the sticky eggs is yellow to orange, the diameter is 2.5 to 3 mm. The embryos are 7.5 to 10 mm in length and able to swim after hatching but stay on the bottom for some time. The embryonic stage is 5 to 16 days, dependent on water temperature (at 19°C and 10°C, respectively). Under natural circumstances the survival from free swimming larva to 75 mm pike is around 5 percent. Pike can reach the reproductive stage in a year, females being 30 cm, males 19 cm. Pike normally live 5 to 15 years, but can be as old as 30. Life expectancy and growth are dependent on circumstances.

Feeding[edit]

Prague Vltava fish exhibition

The young free swimming pike feed on small invertebrates starting with daphnia, and quickly moving on to bigger prey like isopods like asellus or gammarus. When the body length is 4 to 8 cm they start feeding on small fish.

The pike have a very typical hunting behavior; they are able to remain stationary in the water by moving the last fin rays of the dorsal fins and the pectoral fins. Before striking they bend their body and dart out to the prey using the large surface of tail fin, dorsal fin and anal fin to propel themselves. The fish has a distinctive habit of catching its prey sideways in the mouth, immobilising it with its sharp backward pointing teeth, and then turning the prey headfirst to swallow it. It eats mainly fish, but also small mammals and birds fall prey to pike. Young pike have been found dead from choking on a pike of a similar size, an observation referred to by the renowned English poet Ted Hughes in his famous poem 'Pike'.[20] Northern pike also feed on frogs, insects and leeches. They are not very particular and eat spiny fish like perch and will even take sticklebacks if that is the only available prey.

The northern pike is a largely solitary predator. It migrates during a spawning season, and it follows prey fish like Roach (fish) to their deeper winter quarters. Sometimes divers observe groups of similar sized pike that might have some cooperation and it is known to anglers pike tend to start hunting at the same time, so there are some "wolfpack" theories about that. Large pike can be caught on dead immobile fish so it is thought that these pike move about in a rather large territory to find the food to sustain them. Large pike are also known to cruise large water bodies at a few metres depth, probably pursuing schools of prey fish. Smaller pike are more of an ambush predator, probably because of their vulnerability to cannibalism. Pike are often found near the exit of culverts, which can be attributed to the presence of schools of prey fish and the opportunity for ambush. Being potamodromous, all esocids tend to display limited migration, although some local movement may be of key significance for population dynamics. In the Baltic they are known to follow herring schools, and therefore have some seasonal migration.

Importance to humans[edit]

E. lucius caught by an angler in the river Dráva, Hungary

Although generally known as a "sporting" quarry, some anglers release pike they have caught because the flesh is considered bony, especially due to the substantial (epipleural) "Y-bones". Larger fish are more easily filleted, and pike have a long and distinguished history in cuisine and are popular fare in Europe. Historical references to cooking pike go as far back as the Romans. The flesh is white and mild-tasting. Fishing for pike is said to be very exciting with their aggressive hits and aerial acrobatics. Pike are among the largest North American freshwater game fish.

Because of their prolific and predatory nature, laws have been enacted in some places to help stop the spread of northern pike outside of their native range. For instance, in the states of Maine and California, anglers are required, by law, to remove the head from a pike once it has been caught.[21] In Alaska, pike are native north and west of the Alaska Range, but have been illegally introduced to the south central Alaska by game fishermen. In south central Alaska, there is no limit in most areas. Pike are seen as a threat to native wild stocks of salmon by some fishery managers.

Notably in Britain and Ireland, pike are greatly admired as a sporting fish and they are returned alive to the water in order to safeguard future sport and maintain the balance of a fishery.[clarification needed] The Pike Anglers Club has campaigned to preserve pike since 1977, arguing that the removal of pike from waters can lead to an explosion of smaller fish and to ensure pike removal stops, which is damaging to both the sport fishery and the environment.[22]

Geographic distribution[edit]

Esox lucius is found in freshwater throughout the northern hemisphere, including Russia, Europe and North America. It has also been introduced to lakes in Morocco and is even found in brackish water of the Baltic Sea. However pike are confined to the low salinity water at the surface of the Baltic sea, and are seldom seen in brackish water elsewhere.[citation needed]

Within North America, there are northern pike populations in Illinois, North Dakota, South Dakota, Minnesota, Michigan, Montana, Maryland, West Virginia, Wisconsin, Indiana, Connecticut, Rhode Island, New Hampshire, Maine, New Jersey, Massachusetts, Vermont, Iowa, Utah, Northern New Mexico and Arizona, Colorado, New York, Idaho, Alberta, Saskatchewan, Manitoba, Ontario and Québec (pike are rare in British Columbia and east coast provinces), Alaska, the Ohio Valley, the upper Mississippi River and its tributaries, the Great Lakes Basin and surrounding states, Missouri, Kansas, Nebraska, Colorado and parts of Oklahoma. They are also stocked in, or have been introduced to, some western lakes and reservoirs for angling purposes, although some fisheries managers believe this practice often threatens other species of fish such as bass, trout and salmon, causing government agencies to attempt to exterminate the pike by poisoning lakes.[23]

Sport fishing[edit]

Northern Pike caught with fishing lure in Belgium
Fly fishing
BrookTroutAmericanFishes.JPG
targets
bluefish
brook trout
crappie
hucho taimen
largemouth bass
northern pike
peacock bass
shoal bass
smallmouth bass
more fly fish...
other sport fish...

fishing

I N D E X

Pike angling is becoming an increasingly popular pastime in the UK and Europe. Effective methods for catching this hard fighting fish include dead baits, lure fishing, and jerk baiting. They are prized as game fish for their determined fighting and have been food fish since ancient times.

Lake fishing for pike from the shore is especially effective during springtime, at which stage the big pike move into the shallows to spawn in weedy areas, and later many remain there to feed on other spawning coarse fish species to regain their condition after spawning. Smaller jack pike often remain in the shallows for their own protection, and for the small fish food available there. For the hot summer period and during non-active phases the larger female pike tend to retire to deeper water and/or places of better cover. This gives the boat angler good fishing during the summer and winter seasons. Trolling (towing a fairy or bait behind a moving boat) is a popular technique.

The use of float tubes has become a very popular way of fishing for pike on small to medium size stillwaters.[24] Fly fishing for pike is another recently developing way of catching these fish, and the float tube is now recognized as an especially suitable water craft for pike fly-fishing.

In recent decades, more and more pike are released back to the water after catching (catch and release), but they can easily be damaged when handled. Handling those fish with dry hands can easily damage their mucous covered skin and possibly lead to their death from infections.

Since they have very sharp and numerous teeth, care is required in unhooking a pike. It is recommended that barbless trebles are used when angling for this species as it simplifies dehooking. This is undertaken using long forceps, with 30 cm (12 in) artery clamps the ideal tool. When holding the pike from below on the lower jaw, it will open its mouth. The pike should be kept out of the water for the minimum amount of time possible, and should be given extra time to recover if being weighed and photographed before release. If practising live release, it is recommended to call the fish "caught" when it is alongside a boat. Remove the hook by grabbing it with a pair of needle-nosed pliers while the fish is still submerged and giving it a flip in the direction that turns the hook out of the mouth. This avoids damage to the fish and the stress of being out of water.

In Finland, catching a kymppihauki, a pike weighing at least 10 kilograms (22 lb), is considered the qualification as a master fisherman.

Many countries have banned the use of live fish for bait, but it is also possible to catch the pike with dead fish which they locate with smell. For this technique, often fat sea fish like herring, sardines and mackerel are used. This is a particularly good method for catching really big and well fed pike in the colder season. Compared to other fish like the eel, the pike does not have a good sense of smell, but it is still more than adequate to find the baitfish. Baitfish can be used as groundbait, but also below a float carried by the wind. This method is often used in wintertime and best done in lakes near schools of preyfish or at the deeper parts of shallow water bodies, where pike and preyfish tend to gather in great numbers.

Pike make use of the lateral line system to follow the vortices produced by the perceived prey, and the whirling movement of the spinner is probably good way to imitate or exaggerate these. Jerkbaits are also effective and can produce spectacular bites with pike attacking these erratic moving lures at full speed. For trolling, big plugs or softbaits can be used. Spoons with mirror finishes are very effective when the sun is at a sharp angle to the water in the mornings or evenings because they generate the vibrations previously discussed and cause a glint of reflective sunlight that mimics the flash of white-bellied prey. Most fishermen tend to use small lures but often that is not advisable because pike have a preference for large prey. When fishing in shallow water for smaller pike, lighter and smaller lures are frequently used.

See also[edit]

References[edit]

  1. ^ http://www.gen.umn.edu/research/fish/fishes/tiger_muskie.html
  2. ^ "tiger muskellunge (Esox lucius x E. masquinongy) - FactSheet". Nas.er.usgs.gov. Retrieved 2011-03-02. 
  3. ^ Craig, John F. ed. Pike: Biology and Exploitation. Chapman & Hall, London. 1996 pp. 1
  4. ^ "Molecular and Phenotypic Evidence of a New Species of Genus Esox (Esocidae, Esociformes, Actinopterygii): The Southern Pike, Esox flaviae". PLOS ONE. Retrieved 2012-11-20. 
  5. ^ R. O. Anderson and R. M. Neumann, Length, Weight, and Associated Structural Indices, in Fisheries Techniques, second edition, B. E. Murphy and D. W. Willis, eds., American Fisheries Society, 1996.
  6. ^ a b Giles, N., Wright, R. M. and Nord, M. E. (1986), Cannibalism in pike fry, Esox lucius L.: some experiments with fry densities. Journal of Fish Biology, 29: 107–113. doi: 10.1111/j.1095-8649.1986.tb04930.x http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.1986.tb04930.x/abstract
  7. ^ a b 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. Journal of Fish Biology, 8: 179–197. doi: 10.1111/j.1095-8649.1976.tb03930.x, http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.1976.tb03930.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false
  8. ^ a b R. H. K. Mann. Journal of Animal Ecology , Vol. 51, No. 1 (Feb., 1982), pp. 81-95 Published by:British Ecological Society http://www.jstor.org/stable/4312
  9. ^ a b c d e f g A Study of Reproduction, Early Life, Weight-Length Relationship and Growth of Pike, Esox lucius L., in Windermere. Winifred E. Frost and Charlotte Kipling. Journal of Animal Ecology , Vol. 36, No. 3 (Oct., 1967), pp. 651-693. Published by: British Ecological Society. http://www.jstor.org/stable/2820
  10. ^ a b c Peter Eklov. Group foraging versus solitary foraging efficiency in piscivorous predators: the perch, Perca fluviatilis, and pike, Esox Lucius, patterns. Scient Direct. August 1992. Pages 313-326. Volume 44, Part 2. http://www.sciencedirect.com/science/article/pii/000334729290037A
  11. ^ a b c P. Eklov. Effects of Habitat complexity and prey abundance on the spatial and temporal distributions of perch and pike. April 09, 2011. Canadian Journal of Fisheries and Aquatic Sciences. http://www.nrcresearchpress.com/doi/abs/10.1139/f97-059?journalCode=cjfas#.UmnbgxBTVBz
  12. ^ a b c David G. Harper and Robert W. Blake, Fast-Start Performance of Rainbow Trout Salmo Gairdneri and Northern Pike Esox Lucius. January 9, 1990. The Journal of Experimental Biology. http://jeb.biologists.org/content/150/1/321.short
  13. ^ Jepsen, N., Beck, S., Skov, C. and Koed, A. (2001), Behavior of pike (Esox lucius L.) >50 cm in a turbid reservoir and in a clearwater lake. Ecology of Freshwater Fish, 10: 26–34. doi: 10.1034/j.1600-0633.2001.100104.x, http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0633.2001.100104.x/full
  14. ^ Jepsen, N., Beck, S., Skov, C. and Koed, A. (2001), Behavior of pike (Esox lucius L.) >50 cm in a turbid reservoir and in a clearwater lake. Ecology of Freshwater Fish, 10: 26–34. doi: 10.1034/j.1600-0633.2001.100104.x, http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0633.2001.100104.x/full
  15. ^ a b Chapman, C. A. and Mackay, W. C. (1984), Versatility in habitat use by a top aquatic predator, Esox lucius L. Journal of Fish Biology, 25: 109–115. doi: 10.1111/j.1095-8649.1984.tb04855.x, http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.1984.tb04855.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false
  16. ^ Jepsen, N., Beck, S., Skov, C. and Koed, A. (2001), Behavior of pike (Esox lucius L.) >50 cm in a turbid reservoir and in a clearwater lake. Ecology of Freshwater Fish, 10: 26–34. doi: 10.1034/j.1600-0633.2001.100104.x, http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0633.2001.100104.x/full
  17. ^ a b Craig, J. F. and Kipling, C. (1983), Reproduction effort versus the environment; case histories of Windermere perch, Perca fluviatilis L., and pike, Esox lucius L. Journal of Fish Biology, 22: 713–727. doi: 10.1111/j.1095-8649.1983.tb04231.x, http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.1983.tb04231.x/abstract
  18. ^ a b c Donald R. Franklin, Lloyd L. Smith Jr., Early Life History of the Northern Pike, Esox Lucius L., with Special References to the Factors Influencing the Numerical Strength of Year Classes
  19. ^ "pikezander.co.uk". 
  20. ^ Pike by Ted Hughes. Poem text and audio: Hughes talks about his poem then reads it aloud. PoetryArchive.org. Retrieved 2010-08-13.
  21. ^ [1][dead link]
  22. ^ "What the PAC is All About". Pacgb.co.uk. Retrieved 2011-03-02. 
  23. ^ Young, Samantha (2007-09-26). "Calif. Aims to Rid Lake of Northern Pike". Associated Press. Retrieved 2007-09-27. 
  24. ^ [2][dead link]
  • "Esox lucius". Integrated Taxonomic Information System. Retrieved 8 December 2004. 
  • Froese, Rainer and Pauly, Daniel, eds. (2004). "Esox lucius" in FishBase. October 2004 version.
  • Broughton, Bruno. "A Review of the Scientific Basis for Pike Culls". N.p., 2000.
  • Craig, John F. ed. Pike: Biology and Exploitation. Chapman & Hall, London. 1996 pp. 1.
  • Eddy S, Surber T. Northern Game Fishes Univ. of Michigan Press, 1943.
  • La Monte Fancesca. North American Game Fishes Doubleday & Company, Inc. 1950 pp. 126.
  • Weed Alfred C. Pike, Pickerel, and Muskellunge. Field Museum of Natural History, Chicago, Dept. of Zoology, Leaflet No. 9, 52 pp., 8 plates.

External links[edit]