Editing Northern pike (section)

==Behaviour==

===Aggression===
The northern pike is a relatively aggressive species, especially with regard to feeding. For example, when food sources are scarce, [[Cannibalism (zoology)|cannibalism]] develops, starting around five weeks in a small percentage of populations.<ref name="onlinelibrary.wiley.com">{{cite journal | last1 = Giles | first1 = N. | last2 = Wright | first2 = R. M. | last3 = Nord | first3 = M. E. | year = 1986 | title = Cannibalism in pike fry, ''Esox lucius'' L.: some experiments with fry densities | journal = Journal of Fish Biology | volume = 29 | issue = 1 | pages = 107–113 | doi = 10.1111/j.1095-8649.1986.tb04930.x | bibcode = 1986JFBio..29..107G }}</ref> This cannibalism occurs when the ratio of predator to prey is two to one.<ref name="onlinelibrary.wiley.com"/> One can expect this because when food is scarce, Northern pike fight for survival, such as turning on smaller pike to feed; this is seen in other species such as [[tiger salamander]]s. Usually, pike tend to feed on smaller fish, such as the [[banded killifish]]. However, when pike exceed {{convert|700|mm|in|abbr=on}} long, they feed on larger fish.<ref name="Mann, R. H. K. 1976">{{cite journal| last1 = Mann | first1 = R. H. K. | year = 1976 | title = Observations on the age, growth, reproduction and food of the pike ''Esox lucius'' (L.) in two rivers in southern England | journal = Journal of Fish Biology | volume = 8 | issue = 2| pages = 179–197 | doi = 10.1111/j.1095-8649.1976.tb03930.x| bibcode = 1976JFBio...8..179M }}</ref>

Because of cannibalism when food is short, pike suffer a fairly high young mortality rate.<ref name="jstor.org">{{cite journal| first=R. H. K.| last=Mann| title=The Annual Food Consumption and Prey Preferences of Pike (''Esox lucius'') in the River Frome, Dorset| journal=Journal of Animal Ecology| volume=51| issue=1| date=February 1982| pages=81–95| jstor=4312| doi=10.2307/4312| bibcode=1982JAnEc..51...81M}}</ref> Cannibalism is more prevalent in cool summers, as the upcoming pike have slow growth rates in that season and might not be able to reach a size to deter the larger pike. Cannibalism is likely to arise in low growth and low food conditions.<ref name="jstor.org"/> Pike do not discriminate siblings well,{{citation needed|date=July 2018}} so cannibalism between siblings is likely.

Aggression also arises from a need for space.<ref name="Reproduction, Early Life 1967 pp. 651-693">{{cite journal| title=A Study of Reproduction, Early Life, Weight-Length Relationship and Growth of Pike, ''Esox lucius'' L., in Windermere| first1=Winifred E.| last1=Frost |first2=Charlotte |last2=Kipling| author-link2=Charlotte Kipling| journal=Journal of Animal Ecology| volume=36| issue=3| date=October 1967| pages=651–693| jstor=2820| doi=10.2307/2820| bibcode=1967JAnEc..36..651F}}</ref> Young pike tend to have their food stolen by larger pike.<ref name="Reproduction, Early Life 1967 pp. 651-693"/> Pike are aggressive if not given enough space because they are territorial.<ref name="sciencedirect.com">{{cite journal| first=Peter| last=Eklov| title=Group foraging versus solitary foraging efficiency in piscivorous predators: The perch, ''Perca fluviatilis'', and pike, ''Esox lucius'', patterns| journal=Animal Behaviour| date=August 1992| pages=313–326| volume=44| issue=2| doi=10.1016/0003-3472(92)90037-a| s2cid=53196955}}</ref> They use a form of foraging known as ambush foraging. Unlike species such as [[perch]], pike undergo bursts of energy instead of actively chasing down prey. As such, a fair amount of inactive time occurs until they find prey. Hunting efficiency decreases with competition;<ref name="sciencedirect.com"/> the larger the pike, the larger the area controlled by that particular pike. An inverse relation to vegetation density and pike size exists, which is due to the possibility of cannibalism from the largest pike.<ref name="nrcresearchpress.com">{{cite journal| first=P.| last=Eklov| title=Effects of Habitat complexity and prey abundance on the spatial and temporal distributions of perch and pike| date=9 April 2011| journal=Canadian Journal of Fisheries and Aquatic Sciences| volume=54| issue=7| pages=1520–1531| doi=10.1139/f97-059| url=http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88671}}</ref> This makes sense, as the smaller pike need more vegetation to avoid being eaten. Large pike do not have this worry and can afford the advantage of a large line of sight. They prefer a tree structure habitat.<ref name="nrcresearchpress.com"/>

There has been at least one instance of a pike attacking a dog.<ref>Dan Bross, [https://alaskapublic.org/2022/10/21/programmed-to-eat-northern-pike-mauls-husky-at-north-pole-gravel-pit ‘Programmed to eat’: Northern pike mauls husky at North Pole gravel pit]. ''Alaska Public Media'', 21 October 2022, Retrieved 26 October 2022</ref>

Pike are occasionally preyed upon by otters.<ref>Mark Cocker, [https://www.theguardian.com/environment/2013/may/12/claxton-norfolk-pike-huge-otter 'The pike was huge, but not huge enough to fight off an otter']. ''The Guardian'', 12 May 2013. Retrieved 2 May 2022</ref>

===Physical behavioural traits===
Pike are capable of "fast start" movements, which are sudden high-energy bursts of unsteady swimming.<ref name="jeb.biologists.org">{{cite journal| first1=David G.| last1=Harper| first2=Robert W.| last2=Blake| title=Fast-Start Performance of Rainbow Trout ''Salmo gairdneri'' and Northern Pike ''Esox lucius''| date=9 January 1990| journal=The Journal of Experimental Biology| volume=150| issue=1| pages=321–342| doi=10.1242/jeb.150.1.321| url=http://jeb.biologists.org/content/150/1/321.short}}</ref> Many other fish exhibit this movement as well. Most fish use this mechanism to avoid life-threatening situations. For the pike, however, it is a tool used to capture prey from their sedentary positions. They flash out in such bursts and capture their prey. These fast starts terminate when the pike has reached maximum velocity.<ref name="jeb.biologists.org"/> 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".<ref name="jeb.biologists.org"/> An interesting behavioural trait that pike have is that they have short digestion times and long feeding periods.<ref name="Mann, R. H. K. 1976"/> They can undergo many of these fast bursts to collect as much prey as they can. Pike are least active during the night.<ref name="sciencedirect.com"/>

===Reproduction===
Pike have a strong [[homing (biology)|homing]] behaviour;<ref name="nrcresearchpress.com"/> they inhabit certain areas by nature. During the summer, they tend to group closer to vegetation than during the winter.<ref name="Jepsen, N. 2001">{{cite journal | last1 = Jepsen | first1 = N. | last2 = Beck | first2 = S. | last3 = Skov | first3 = C. | last4 = Koed | first4 = A. | year = 2001 | title = Behavior of pike (''Esox lucius'' L.) > 50 cm in a turbid reservoir and in a clearwater lake | journal = Ecology of Freshwater Fish | volume = 10 | issue = 1 | pages = 26–34 | doi = 10.1034/j.1600-0633.2001.100104.x | bibcode = 2001EcoFF..10...26J }}</ref> The exact reason is not clear, but likely is a result of foraging or possibly reproductive needs to safeguard young. Pike [[Diel vertical migration|diel]] rhythm changes significantly over the year.<ref name="Jepsen, N. 2001"/> On sunny days, pike stay closer to the shallow shore. On windy days, they are further from shore.<ref name="Chapman, C. A 1984">{{cite journal | last1 = Chapman | first1 = C. A. | last2 = Mackay | first2 = W. C. | year = 1984 | title = Versatility in habitat use by a top aquatic predator, ''Esox lucius'' L | journal = Journal of Fish Biology | volume = 25 | issue = 1 | pages = 109–115 | doi = 10.1111/j.1095-8649.1984.tb04855.x | bibcode = 1984JFBio..25..109C }}</ref> When close to the shore, pike have a preference for shallow, vegetated areas.<ref name="Chapman, C. A 1984"/> Pike are more stationary in reservoirs than lakes.<ref name="Jepsen, N. 2001"/> 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 breed in the spring.<ref name="Reproduction, Early Life 1967 pp. 651-693"/>

Pike are physically capable of [[breeding in the wild|breeding]] at an age of about two years, [[Spawn (biology)|spawning]] in spring when the water temperature first reaches about {{convert|9|C|F}}. They have a tendency to lay a large number of eggs.<ref name="Reproduction, Early Life 1967 pp. 651-693"/> A likely explanation for such actions is to produce as many surviving offspring as possible, as many most likely die early in life. In females, the [[gonad]]s enlarge when it is time to shed her eggs.<ref name="Reproduction, Early Life 1967 pp. 651-693"/> However, after they are shed, these eggs will not hatch if the water is below {{convert|6|C|F}}.<ref name="Reproduction, Early Life 1967 pp. 651-693"/> Male pike arrive at the breeding grounds before females do, preceding them by a few weeks. In addition, the males stay after the spawning is finished.<ref name="Reproduction, Early Life 1967 pp. 651-693"/> Parental stock is vital for pike success.<ref name="Craig, J. F 1983">{{cite journal | last1 = Craig | first1 = J. F. | last2 = Kipling | first2 = C. | year = 1983 | title = Reproduction effort versus the environment; case histories of Windermere perch, ''Perca fluviatilis'' L., and pike, ''Esox lucius'' L | journal = Journal of Fish Biology | volume = 22 | issue = 6| pages = 713–727 | doi = 10.1111/j.1095-8649.1983.tb04231.x| bibcode = 1983JFBio..22..713C }}</ref> Egg survival has been shown to be positively correlated with number of eggs laid.<ref name="Craig, J. F 1983"/> For breeding, the more stable the water, the greater the fitness of the pike.<ref name="ReferenceA">{{Cite journal | doi=10.1577/1548-8659(1963)92[91:ELHOTN]2.0.CO;2| year=1963| volume=92| page=91| title=Early Life History of the Northern Pike, ''Esox lucius'' L., with Special Reference to the Factors Influencing the Numerical Strength of Year Classes| last1=Franklin| first1=Donald R.| last2=Smith| first2=Lloyd L.| journal=Transactions of the American Fisheries Society| issue=2}}</ref> Mortality results from toxic concentrations of iron or rapid temperature changes,<ref name="ReferenceA"/> and 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 [[blastopore]], and the second between hatching and the termination of the [[alevin]] stage.<ref name="ReferenceA"/>
 
The colour of the sticky eggs is yellow to orange; the diameter is {{convert|2.5|to|3|mm|abbr=on}}. The embryos are {{convert|7.5|to|10|mm|abbr=on}} in length and able to swim after hatching, but stay on the bottom for some time. The embryonic stage is five to 16 days, dependent on water temperature (at {{convert|19|C|F}} and {{convert|10|C|F}}, respectively). Under natural circumstances, the survival from [[Fish larva|free-swimming larva]] to 75-mm pike is around 5%.{{citation needed|date=April 2016}}