Esox

How to read a taxoboxEsox
Fossil range: Upper Cretaceous–Recent
[1]
Northern pike (E. lucius)
Northern pike (E. lucius)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Superorder: Protacanthopterygii
Order: Esociformes
Family: Esocidae
G. Cuvier, 1817
Genus: Esox
Linnaeus, 1758
Type species
Esox lucius
Linnaeus, 1758

Esox is a genus of freshwater ray-finned fish, whose members are known as pike, pickerel, and muskellunge, and are characterized by a pronounced snout, forked caudal fin, complete lateral line, posteriorly located dorsal and anal fins, forked caudal fin, and no adipose fin. Esox is the only extant genus in the pike family Esocidae of the order Esociformes (with the mudminnows, family Umbridae, also placed in the order).

Of the five traditionally recognized extant species in Esox, the type species, E. lucius (the northern pike) is the only circumpolar member, while E. richerti (Amur pike) is located in Siberia, and three species, E. masquinongy (muskellunge), E. niger (chain pickerel), and E. americanus (redfin and grass pickerel) are restricted to eastern North America. However, in 2011 support was provided for the delineation of a sixth species, variously identified as E, flaviae or E. cisalpinus. This species, which has sometimes been designated the southern pike, is restricted to freshwater habitats in Southern Europe. Previously, it was thought that the northern pike was the only extant species in Europe and that this new species was only a color variation.

The largest member of the genus and family is the muskellunge (E. masquinongy) (also known as the musky or muskie) which reaches 1.8 meters (6 feet).

The Esox genus provides important values for humans and the ecosystem. The pike, pickerel, and muskellunge are all popular fish for angling, and while the many small bones can make preparation difficult, they provide a tasty food as well. In addition, the pike, pickerel, and muskies play important roles in food chains, consuming prey ranging from small invertebrates such as daphnia and isopods (when young), to insects, crayfish, amphibians (newts, frogs), smaller fish, semi-aquatic snakes, and even small mammals like duckings, and even mice and moles when they find themselves in the water. While adult muskellunge are apex predators, the juveniles are consumed by other fish and birds of prey.

Contents

Overview and description

The Esox genus is the only living genus in the pike family, Esocidae, in the order Esociformes of the class Actinopterygii. Members of the Esociformes, which also include the mudminnows (family Umbridae), are characterized by posteriorly located dorsal and anal fins, the lack of an adipose fin, toothless maxilla but in the gape of the mouth, and no pyloric caeca. Members of the family Esocidae, the esocids, are characterized by a forked caudal fin with 40 to 50 rays, a complete lateral line, 10 to 20 branchiostegal rays, nasals present, snout produced, and 43 to 67 vertebrae. The other family of Esociformes, the Umbridae, differs in that the mudminnows have a rounded caudal fin with 20 to 30 rays, a lateral line that is faint or absent, nasals absent, snout not produced, only 32 to 42 vertebrae, and 5 to 8 branchiostegal rays (Nelson 2006).

Members of the Esox genus have the elongated, torpedo-like form of predatory fishes, with sharply-pointed heads and sharp, fang-like teeth set in powerful jaws shaped like the bill of a duck. Their coloration is typically grey-green with a mottled or spotted appearance with stripes along their back, perfectly camouflaged among weeds. Individual pike marking patterns are unique, like fingerprints.

Muskellunge

Muskellunge (E. masquinongy)

The largest living member of the esocids is the muskellunge (E. masquinongy). Muskellunge, or musky, closely resemble other esocids in both appearance and behavior. Like other pikes, the body plan is typical of ambush predators with an elongated body, flat head and dorsal, pelvic and anal fins set far back on the body. Muskellunge are a light silver, brown, or green with dark vertical stripes on the flank, which may tend to break up into spots. In some cases, markings may be absent altogether, especially in fish from turbid waters. This is in contrast to northern pike, which have dark bodies with light markings. A reliable method to distinguish the two similar species is by counting the sensory pores on the underside of the mandible. A muskie will have seven or more per side, while the northern pike never has more than six. The lobes of the caudal (tail) fin in muskellunge come to a sharper point, while those of northern pike are more generally rounded. In addition, unlike pike, muskies have no scales on the lower half of their opercula.

Muskellunge are typically 28–48 inches (0.71–1.2 m) long and weigh 5–36 pounds (2.3–16 kg) (Michigan DNR 2013); the maximum recorded length is 1.83 meters (6.0 ft) and the maximum recorded weight 35 kilograms (77 lb). Generally, pike over 8 kilograms (18 lb) in body weight are females. Muskellunge individuals have been reported to reach 30 years in age.

Muskellunge are found in oligotrophic and mesotrophic lakes and large rivers from northern Michigan, northern Wisconsin and northern Minnesota through the Great Lakes region, north into Canada, throughout most of the St Lawrence River drainage and northward throughout the upper Mississippi valley, although the species also extends as far south as Chattanooga in the Tennessee River valley. There is also a small population in the Broad River in South Carolina. Several North Georgia reservoirs also have healthy stocked populations of muskie. They are also found in the Red River drainage of the Hudson Bay basin. They prefer clear waters where they lurk along weed edges, rock outcrops or other structures to rest. A fish forms two distinct home ranges in summer: a shallow range and a deeper one. The shallow range is generally much smaller than the deeper range due to shallow water heating up. A musky will continually patrol the ranges in search of available food in the appropriate conditions of water temperature.

Northern pike

Drawing of Esox lucius

The type species of Esox is E. lucius, the northern pike. 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.

Northern pike weight length graph.jpg

Northern pike grow to a relatively large size; lengths of 150 centimeters (59 in) and weights of 25 kilograms (55 lb) are not unheard of.

E. 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.

A hybrid between northern pike and muskellunge is known as a tiger muskellunge (Esox masquinongy × lucius or Esox lucius × masquinongy, depending on the sex of each of the contributing species). In the hybrids, the males are invariably sterile, while females are sometimes fertile, and may back-cross with the parent species.

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 (Craig 1996).

Chain pickerel

Chain pickerel (E. niger)

The chain pickerel (Esox niger, syn. E. reticulatus) has a distinctive dark chain-like pattern on its greenish sides. Its body outline resembles that of the northern pike. The opercles and cheeks of the fish are entirely scaled. It may reach up to 30 inches only on rare occasions. The average size for chain pickerel, however, is 24 inches and 3 pounds. (The average chain pickerel caught by fishermen is under 2 pounds).

The chain pickerel's range is along the eastern coast of North America from southern Canada to Florida, and west to Texas. On the Atlantic Coast, in Maine, New Brunswick and Nova Scotia, the chain pickerel extend as far as 46 degrees north latitude. The fish inhabits freshwater from the Mississippi Valley into southern Wisconsin. It also is commonly found in Lake Michigan and the lower portion of the Great Lakes (Weed 1927).

American pickerel

Redfin pickerel (E. americanus americanus)
Grass pickerel (Esox americanus vermiculatus)

The American pickerels are two subspecies of Esox americanus: the redfin pickerel, E. americanus americanus Gmelin, 1789, and the grass pickerel, E. americanus vermiculatus Lesueur, 1846.

The two subspecies are very similar, but the grass pickerel lacks the redfin's distinctive orange to red fin coloration, its fins having dark leading edges and amber to dusky coloration. In addition, the light areas between the dark bands are generally wider on the grass pickerel and narrower on the redfin pickerel. These pickerels grow to a maximum overall length of 40 cm (16 in) and a maximum weight of 2.25 pounds.

Both subspecies are native to North America. The redfin pickerel's range extends from the Saint Lawrence drainage in Quebec down to the Gulf Coast, from Mississippi to Florida, while the grass pickerel's range is further west, extending from the Great Lakes Basin, from Ontario to Michigan, down to the western Gulf Coast, from eastern Texas to Mississippi.

Amur pike

The Amur pike, also known as the blackspotted pike, Esox reichertii, is native to the Amur River system in east Asia, as well as freshwater habitat on the island of Sakhalin. It reaches a length of 115 cm, sporting a silvery body with small black spots.

Taxonomy

Traditionally, five species in Esox were recognized (ITIS 2003). In 2011, Lucentini et al. published a paper delineating a new species in Southern Europe that differed from the northern pike (E. lucius) at phenotypic, genotypic and geographical levels . The researchers named the species Esox flaviae. It had long been thought that it was only a color variation of the northern pike. In 2011, another species in Southern Europe was likewise identified by Bianco & Delmastro and labelled Esox cisalpinus It appears the two species may be synonyms, with E. cisalpinus Bianco & Delmastro, 2011 possibly being the senior synonym (Fishbase 2013).

Esox cisalpinus

The six currently recognized extant species are (Fishbase 2013):

  • Esox americanus
    • Esox americanus americanus J. F. Gmelin, 1789 (Redfin pickerel)
    • Esox americanus vermiculatus Lesueur, 1846 (Grass pickerel)
  • Esox cisalpinus Bianco & Delmastro, 2011
    • synonym: Esox flaviae Lucentini, Puletti, Ricciolini, Gigliarelli, Fontaneto, Lanfaloni, Bilò, Natali & Panara 2011 (Southern pike)
  • Esox lucius Linnaeus, 1758 (Northern pike)
  • Esox masquinongy Mitchill, 1824 (Muskellunge)
  • Esox niger Lesueur, 1818 (Chain pickerel)
  • Esox reichertii Dybowski, 1869 (Amur pike)

There is one fossil species, Esox kronneri Grande, 1999 known from the Eocene of the Green River formation (Grande 1999).

Etymology and plural of terms

The plural of muskellunge is muskellunge. The plural of pickerel may be pickerel or pickerels and likewise the plural of pike may be pike or pikes.

A young E. lucius specimen in an aquarium.

The generic name Esox (pike fish) derives from the Greek ίσοξ (a kind of fish), itself a word of Celtic origin related to the Welsh eog and Irish Gaelic iasc (fish). Pliny uses the Latin form esox in reference to a large fish in the Rhine normally identified with lax (salmon). It is likely that Carolus Linnaeus's application of Esox to the pike is thus a misnomer.

The English common name "pike" is an apparent shortening of "pike-fish", in reference to its pointed head, Old English píc originally referring to a pickaxe. The northern pike also has been said to get its name from its resemblance to the pole-weapon known as the pike (from the Middle English for pointed).

A northern English and Lowland Scots name for the pike, ged, similarly derives from Old Norse gaddr (spike) (cf. the modern Swedish name for the pike, gädda, the Danish "gedde", the Norwegian "gjedde" and Scottish Gaelic: geadais). The Dutch name for the pike (snoek) has been given to a wide variety of fish reminding sailors of the pike (see snoek, snook).

The English "pike" originally referred specifically to the adult fish, the diminutive form "pickerel" (now used to name some of the smaller pike, E. americanus and E. niger) referring to the young. The walleye (Sander vitreus) is sometimes called a pickerel by Gerard, but it is unrelated to the pike, being a member of the perch family (family Percidae). Pike are not to be confused with the unrelated pikeminnows (traditionally, and perhaps better, known as squawfish) of genus Ptychocheilus (family Cyprinidae) or pikeperch (Sander lucioperca) which is more akin to walleye than to pike. Pike are also called "Jackfish" in North America and informally "Slough Shark" in Western Canada.

Diet

Pike in Haus des Meeres, Vienna

The chain pickerel feeds primarily on smaller fish, which it ambushes from cover with a rapid lunge and secures with its sharp teeth. Chain pickerel are also known to eat frogs, worms, mice, crayfish, and a wide variety of other foods (Sternberg 1987). It is not unusual for pickerel to leap out of the water at flying insects, or even at dangling fishing lures.

Northern pike feed on a wide range of food sources, predominantly smaller shoal fish. Pike are also cannibalistic, sometimes preying upon smaller members of their own species. They will also prey on insects and amphibians such as newts or frogs in times when their usual food is scarce, and occasionally on small mammals like moles or mice when caught water-borne. Small birds such as ducklings may become a target for hungry pike. Pike are also known to prey on swimming snakes.

The young northern 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 breast 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, immobilizing 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. 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 northern pike are more of an ambush predator, probably because of their vulnerability to cannibalism. Pikes 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.

Adult muskellunge are apex predators where they occur naturally. Only humans pose a threat to an adult but juveniles are consumed by other muskies, northern pike, bass, and occasionally birds of prey. The musky's low reproductive rate and slow growth render populations highly vulnerable to overfishing. This has prompted some jurisdictions to institute artificial propagation programs in an attempt to maintain otherwise unsustainably high rates of angling effort and habitat destruction.

Pikes are undeserving of their reputation for being overly vicious predators. There are few substantiated incidents of pike 'attacks' on people.

Angling

Sign on the River Shannon, Ireland
A caught pike

Sportsfishing is quite popular for the large northern pike and muskellunge, as these fish combine size with strength. Effective methods for catching these fish include dead baits, live baits, and lure fishing. Since all species have very sharp and numerous teeth, care is required in unhooking them, including the use of forceps, needle-nosed pliers, and hooks without barbs. Many anglers now use special grips to grab the pike's front lower jaw, which can add to the safety of an anglers because of the danger imposed by the hooks of the lure or tackle and the pike's teeth. Note that these fish can easily be damaged when handled since they are not as robust as their reputation would suggest. In particular, the formerly recommended practice of grasping a pike by its eye sockets should not be used unless the plan is to keep the fish for consumption, since such a practice injures the fish, often with fatal results after released.

A practice known as gut hooking was previously widely used in catching pike. Upon taking the bait, the pike will hold it for a short time in its mouth as it moves off. The pike will then, usually, turn the bait in its mouth, so that it sits in alignment with its throat to ease swallowing. It is recommended that when pike fishing the process is not allowed to go this far and a strike is recommended as soon as a bite is indicated. For this it is necessary to attach hooks on the head side as well as the middle of the baitfish. Otherwise, what is known as gut hooking will result, which will normally kill or seriously injure the fish.

Other methods of catching and handing pike that are now frowned upon are the gaff and the gag. The gaff is a metal hook on the end of a pole used to hook through the fish's body in place of a more humane landing net. A gag is a device for holding open the pike's mouth while unhooking. These are now illegal in Scotland, as they put a huge amount of pressure on a pike's jaw, thus causing irreparable damage.

While the meat of members of the this genus is white, lean, and flavorful, the many small bones can make preparation difficult.

Heraldry

In heraldry, the pike is called a lucy (Fox-Davies 1909) It is usually blazoned either naiant (swimming), embowed (bowed) or hauriant (jumping), though pairs of lucies may appear addorsed (back to back), as in the arms of the Finnish town of Uusikaupunki, Finland.

Uusikaupunki coat of arms
Coat of arms of Gimte, in Lower Saxony, Germany.

Notes

References

  • Craig, J. F. (Ed.) 1996. Pike: Biology and Exploitation. London: Chapman & Hall. ISBN: 9780412429606.
  • Grande, L. 1999. The first Esox (Esocidae: Teleostei) from the Eocene Green River Formation, and a brief review of esocid fishes. Journal of Vertebrate Paleontology 19(2): 271-292.
  • Integrated Taxonomic Information System (ITIS). 2003. Esox Linnaeus, 1758 ITIS Taxonomic Serial No.: 162138. Retrieved June 27, 2013.
  • Nelson, J. S. 2006. Fishes of the World, 4th edition. Hoboken, NJ: John Wiley & Sons. ISBN 0471250317.
  • Sternberg, D. 1987. Freshwater Gamefish of North America. Minnetonka, Minn.: DeCosse. ISBN 0865730237.
  • Weed, A. C. 1927. 'Pike, Pickerel and Muskalonge. Zoology Leaflet 9, Field Museum of Natural History.

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