Esox lucius

The northern pike (Esox lucius), known simply as a pike in Britain, Ireland, and the USA, or as jackfish in Canada), is a popular sporting and food fish that inhabits freshwaters around the northern hemisphere, and are found in brackish waters of the Baltic Sea. Northern pike in Europe can grow up to about 25 kg and 150 cm long; females are generally larger than males. They become sexually mature at 3-4 years of age, and live between 10-12 years. Solitary and territorial, these fish ambush predators. As young fish they feed on small invertebrates, and as they grow older their broad diet grows to include amphibians and fish of all sorts (including their own kind), and even small mammals and birds. Pike has been used to stock waterways (often illegally) in many areas, and has impacted native fish populations and fish communities in negative ways. In Alaska, Colorado, Montana and Maine, E. lucius have been documented as threatening stickleback and native salmonids. The northern pike can hybridize with the closely related muskellunge E. masquinongy, and in some areas E. lucius threaten native muskellunge populations.

( Department of Natural Resources; Fuller 2012; Wikipedia 2012)

Pike spawn from the end of March to the beginning of May, usually in quite shallow water and often using the same places year after year. The spawning process can last several weeks and the number of eggs varies with the age and size of the female. A large fish may produce as many as half a million eggs. The eggs are sticky and adhere to plants, the young pike hatching after 10 – 15 days. At this stage they have no proper mouthparts and remain attached to the plants until the yoke sac is consumed. Once the young fish become free-swimming, they feed mainly on small organisms, but once they reach a length of 5 cm, they begin preying on other fish larvae and tadpoles. Once they have survived these early stages, pike grow fast, sometimes reaching a weight of one kilogram in the space of three years. Males mature at the age of two, females at four years. Pike catch their food largely by stealth and lightning-fast acceleration, taking their prey unawares. A large adult pike will eat roach, rudd, dace and perch, trout and salmon, and even other members of their own species. They will also take frogs, newts, crayfish and they have been known to catch ducklings and small mammals.

An adult female pike can grow to more than 1.40 meters long. Males 'only' grow up to 85 centimeters. The pike is a true predator fish. It used to be assumed that it hunts particularly by sight however that is not true. It tracks its prey primarily using its side-line system, a separate nervous system appearing as a line along its flanks. It lies dead still in the water and snaps at prey that happens to pass by. The greatest enemy of young pike (pickerel) is its own larger species. Therefore, pickerels hide among underwater growth until they are large enough not to be eaten by other pike.

The pike is probably the coarse anglers' most sought-after fish. It is predatory both in nature and appearance. The fish has a flat, broad, almost duck-like snout and an elongated, streamlined body with dorsal and anal fins placed well back. The colour of the fish varies with its habitat, those living in weeded waters being predominantly mottled green and yellow. Fish from brackish waters are more yellowish. Pike turn darker with age, old specimens becoming brown or even greyish. Pike are the subject of innumerable fishy stories, with many telling of 'the one that got away'. Establishing the weight of the largest pike on record in the UK is almost as tricky as catching the actual fish might have been. According to the Pike Angler's Club of Great Britain, the record goes to one caught on a rod and line in Llandegfedd Reservoir, Wales, in 1992. That fish weighed 46lb 13oz (21.3 kg). However, there is also a Scottish record dating back to 1945 which refers to a fish caught in Loch Lomond that weighed 47lb 11oz (21.6 kg).

Occurs in clear vegetated lakes, quiet pools and backwaters of creeks and small to large rivers (Ref. 5723). Usually solitary and highly territorial. Enters brackish water in the Baltic. Adults feed mainly on fishes, but at times feed heavily on frogs and crayfish (Ref. 27547). Cannibalism is common. In arctic lakes, it is sometimes the only species present in a given water body. In such cases, juveniles feed on invertebrates and terrestrial vertebrates; large individuals are mainly cannibals (Ref. 59043). Cannibalistic as juveniles (Ref. 30578). Feces of pike are avoided by other fish because they contain alarm pheromones. Deposits feces at specific locations, distant from its foraging area (Ref. 59043). Eggs and young are preyed upon by fishes, aquatic insect larvae, birds, and aquatic mammals (Ref. 1998). Does not generally undertake long migrations, but a few may move considerable distances (Ref. 27547). Oviparous (Ref. 205). This fish can be heavily infested with parasites, including the broad tapeworm which, if not killed by thorough cooking, can infect human; is used as an intermediate host by a cestode parasite which results to large losses in usable catches of lake whitefish (Coregonus clupeaformis) in some areas; also suffers from a trematode which causes unsightly cysts on the skin (Ref. 9988). Excellent food fish; utilized fresh and frozen; eaten pan-fried, broiled, and baked (Ref. 9988). Valuable game fish (Ref. 5723). In spite of numerous attempts to culture this species, it was never entirely domesticated and does not accept artificial food (Ref. 30578). Locally impacted by habitat alterations (Ref. 59043).

The range of the pike encompasses many northern latitude countries, including: the USA (north of the prairies), southern Canada, the UK and most of Europe (except Iberia), western Scandinavia, the Baltic States, Russia south to the Caspian Sea and eastwards through southern Siberia to the Baring Straits.

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Range is Holarctic and includes the Atlantic, Arctic, Pacific, Great Lakes, and Mississippi River basins from Alaska to Labrador, south to Pennsylvania, Missouri, and Nebraska (Page and Burr 2011). This species has been introduced in many areas southward of the native range.

Esox lucius are native to North America and Eurasia. They are found from Labrador west to Alaska, south to Pennsylvannia, Missouri and Nebraska. In Europe they are found throughout northern and western Europe and south throughout Spain and east to Siberia.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

Other Geographic Terms: holarctic

Baltic sea, Black Sea, British Columbia, Canadian Exclusive Economic Zone [Pacific part], Coastal Waters of Southeast Alaska and British Columbia, FAO fishing area 67, Gulf of St. Lawrence, Hudson Bay, Hudson Strait, IJsselmeer, North East Pacific, North Pacific, North West Territories, Polish Exclusive Economic Zone, Portuguese Exclusive Economic Zone, Schelde estuary, Spanish Exclusive Economic Zone, Swedish Exclusive Economic Zone, Ungava Bay, United Kingdom Exclusive Economic Zone, Westerschelde, Zeeschelde

Circumpolar in fresh water. North America: Atlantic, Arctic, Pacific, Great Lakes and Mississippi River basins from Labrador to Alaska and south to Pennsylvania, Missouri and Nebraska, USA (Ref. 5723). Eurasia: Caspian, Black, Baltic, White, Barents, Arctic, North and Aral Seas and Atlantic basins, southwest to Adour drainage; Mediterranean basin in Rhône drainage and northern Italy. Widely distributed in central Asia and Siberia easward to Anadyr drainage (Bering Sea basin). Historically absent from Iberian Peninsula, Mediterranean France, central Italy, southern and western Greece, eastern Adriatic basin, Iceland, western Norway and northern Scotland. Widely introduced and translocated throughout Europe (Ref. 59043). Several countries report adverse ecological impact after introduction (Ref. 1739).

Caspian, Black, Baltic, White, Barents, Arctic, North and Aral Seas and Atlantic basins, southwest to Adour drainage; Mediterranean basin, in Rhône drainage and northern Italy. Widely distributed in North America and Siberia eastward to Anadyr drainage (Bering Sea basin). Historically absent from Iberian Peninsula, Mediterranean France, central Italy, southern and western Greece, eastern Adriatic basin, Iceland, western Norway and northern Scotland. Now widely introduced and translocated throughout Europe.

Esox lucius are native to North America and Eurasia. They are found from Labrador west to Alaska, south to Pennsylvannia, Missouri and Nebraska. In Europe they are found throughout northern and western Europe, south throughout Spain and east to Siberia.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

Other Geographic Terms: holarctic

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Circumpolar in Northern Hemisphere.

Northern pike average 46 to 51 cm (18-20 inches) in length. They can be identified by their single dorsal fin and light-colored spots along their dark body. They are also recognized by scales that cover their entire cheek and the upper half of their gill covers. The sides of Esox lucius vary from dark shades of green to olive green to brown, with 7 to 9 rows of yellowish, bean-shaped spots. The underside is white to cream-colored.

Range mass: 0.5 to 1.4 kg.

Range length: 46 to 51 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes alike

Dorsal soft rays (total): 17 - 25; Analsoft rays: 10 - 22; Vertebrae: 57 - 65

Northern pike average 46-51 cm (18-20 inches) in length. They can be identified by their single dorsal fin and light-colored spots along their dark body. They are also recognized by scales that cover their entire cheek and the upper half of their gill covers. Their close relative, the muskellunge (Esox masquinongy), have scales covering only the upper half of their cheek and gill covers. The sides of E. lucius vary from dark shades of green to olive green to brown, with 7 to 9 rows of yellowish, bean-shaped spots. The underside is white to cream-colored.

Range mass: 0.5 to 1.4 kg.

Maximum size: 1000 mm TL

137 cm FL (male/unsexed; (Ref. 40637)); 150 cm TL (female); max. published weight: 28.4 kg (Ref. 40637); max. published weight: 35 kg; max. reported age: 30 years (Ref. 556)

Length: 133 cm

Diagnosed from all other freshwater fishes in Europe by the combination of the following characters: long snout; large mouth; dorsal fin origin slightly in front of anal origin; and lateral line with 105-148 scales (Ref. 59043). Distinguished by its long, flat, 'duck-bill' snout; its large mouth with many large, sharp teeth; and the rearward position of its dorsal and anal fins (Ref. 27547). Gill rakers present only as patches of sharp teeth on gill arches; lateral line notched posteriorly (Ref. 27547). Dorsal located far to the rear; anal located under and arising a little behind dorsal; pectorals low on body, base under opercle; pelvic fins low on body; paired fins rounded, paddle-shaped (Ref. 27547). Caudal fin with 19 rays (Ref. 2196).

This taxon is one of a number of demersal species in the Seine River system of Western Europe. Demersal river fish are found at the river bottom, feeding on benthos and zooplankton

The Marne and Yonne exhibit the greatest torrential flows, due to the percentage of their courses underlain by impermeable strata, in combination with the river gradients. Although the Loing manifests the highest percentage of impermeable strata of all the tributaries, its low gradient mitigates against torrential velocities. Thus the majority of the Seine and its tributaries exhibit a relaxed generally even flow rate.

Seine water pollutant loads of heavy metals, nutrients, sediment and bacteria are relatively high, especially influnced by wastewater and surface runoff from Paris and its suburbs. Parisian pollutant loadings are noted to be particularly high during periods of high rainfall, not only due to high runoff, but also from the inadequate sewage treatment facilities in periods of high combined wastewater/stormwater flow.

Heavy metal concentrations at Poses weir reveal the following levels: copper, 1.9 milligrams per liter; cadmium, 32 mg/l; and lead, 456 mg/l. Concentrations of zinc are also quite high, making the Seine Estuary one of the most highly contaminated estuaries in the world with respect especially to lead and cadmium. Significant amounts of toxic pollutants are also attached to sediments deposited in the Seine during the last two centuries, including mercury, nickel, chromium, toluene, DDT and a variety of herbicides and pesticides. Downriver from Paris, significant quantites of ammonium are discharged into the Seine from effluent of the Achères wastewater treatment plant.

There are a total of 37 fish species inhabiting the Seine, and another two taxa that are known to have been extirpated in modern times. Two of the largest aquatic fauna known to have lived in the Seine are now locally extinct: the 500 centimeter (cm) long sturgeon (Acipenser sturio) and the 83 cm long allis shad (Alosa alosa).

The largest extant native demersal (species living on or near the river bottom) taxa in the Seine are:

the 133 cm European eel (Anguilla anguilla);
the 150 cm northern pike (Esox lucius);
the 120 cm sea lamprey (Petromyzon marinus); and,
the 152 cm Burbot (Lota lota).

Habitat Type: Freshwater

Comments: This fish usually occurs in clear small lakes, shallow vegetated areas of larger lakes, marshes, creeks, and small to large rivers. It moves to deeper cooler water in summer. Spawning occurs in shallow flooded marshes associated with lakes, inlet streams to those lakes (or flooded terrestrial vegetation at reservoir edge), or rivers; spawning habitat is basically a flooded area with emergent vegetation (optimally over short grasses or sedges). Young remain in spawning habitat for several weeks after hatching.

Esox lucius are found in almost every type of freshwater, from cold deep lakes, to warm shallow ponds, to muddy rivers. Because they have a broad range of tolerances for water temperature, clarity and oxygen content they are an especially adaptable species of freshwater fish.

Habitat Regions: temperate ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams

demersal; potamodromous; freshwater; brackish; depth range 0 - 30 m (Ref. 1998), usually 1 - 5 m (Ref. 1998)

Habitat and Ecology

Systems

• Freshwater

Esox lucius are found in almost every type of freshwater, from cold deep lakes, to warm shallow ponds, to muddy rivers. Having a broad range of tolerances for water temperature, clarity and oxygen content allows E. lucius to be "one of the most adaptable freshwater species" (Steinberg, 1992, pg. 20).

Aquatic Biomes: lakes and ponds; rivers and streams

Depth range based on 2801 specimens in 1 taxon.
Water temperature and chemistry ranges based on 237 samples.

Environmental ranges
  Depth range (m): 0 - 64
  Temperature range (°C): 3.141 - 7.898
  Nitrate (umol/L): 1.212 - 5.208
  Salinity (PPS): 5.681 - 8.865
  Oxygen (ml/l): 3.529 - 8.684
  Phosphate (umol/l): 0.114 - 1.557
  Silicate (umol/l): 12.053 - 35.741

Graphical representation

Depth range (m): 0 - 64

Temperature range (°C): 3.141 - 7.898

Nitrate (umol/L): 1.212 - 5.208

Salinity (PPS): 5.681 - 8.865

Oxygen (ml/l): 3.529 - 8.684

Phosphate (umol/l): 0.114 - 1.557

Silicate (umol/l): 12.053 - 35.741
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Depth: 0 - 30m.
Recorded at 30 meters.

Habitat: demersal. Occurs in clear vegetated lakes, quiet pools and backwaters of creeks and small to large rivers. Usually solitary. Highly territorial predator. Enters brackish water in the Baltic. After the yolk is absorbed, young feed on large zooplankton and immature aquatic insects for about 7-10 days; fish then becomes the major part of the diet (Ref. 1998). Adults occasionally feed on frogs, crayfish and other vertebrates (Ref. 1998). Eggs and young are preyed upon by fishes, aquatic insect larvae, birds, and aquatic mammals (Ref. 1998). Adults are preyed upon bears, dogs, eagles, and osprey during the spawning run (Ref. 1998). Valuable game fish. This fish can be heavily infested with parasites, including the broad tapeworm which, if not killed by thorough cooking, can infect human; is used as an intermediate host by a cestode parasite which results to large losses in usable catches of lake whitefish (@Coregonus clupeaformis@) in some areas; also suffers from a trematode which causes unsightly cysts on the skin (Ref. 9988). Excellent food fish; utilized fresh and frozen; eaten pan-fried, broiled, and baked (Ref. 9988).

Pike can be found in many water bodies provided there is plenty of oxygen and a neutral or alkaline pH. They occur in lakes with plenty of vegetation, rivers and creeks. They occasionally venture into brackish water.

Potamodromous. Migrating within streams, migratory in rivers, e.g. Saliminus, Moxostoma, Labeo. Migrations should be cyclical and predictable and cover more than 100 km.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

May migrate between spawning and nonspawning habitats.

Esox lucius are carnivorous fish. Because they are equipped with sharp teeth and very complex skull and jaw structures, they are able to feed on smaller Actinopterygii, Anura, Cambaridae, small Mammalia and Aves.

Animal Foods: birds; mammals; amphibians; fish; aquatic crustaceans

Occurs in clear vegetated lakes, quiet pools and backwaters of creeks and small to large rivers (Ref. 5723, 10294). Usually solitary and highly territorial. Enters brackish water in the Baltic. Adult feeds mainly on fishes, but at times feeds heavily on frogs and crayfish (Ref. 27547). Cannibalistic as juveniles (Ref. 30578). Eggs and young are preyed upon by fishes, aquatic insect larvae, birds, and aquatic mammals (Ref. 1998). Does not generally undertake long migrations, but a few may move considerable distances (Ref. 27547).

Esox lucius are a carnivorous fish. Equipped with sharp teeth and very complex skull and jaw structures they are predators of smaller fish, frogs, crayfish, small mammals and birds.

Animal Foods: birds; mammals; amphibians; fish; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

Comments: Young initially eat large zooplankton and immature aquatic insects. After 7-10 days fishes begin to enter diet and eventually dominate. Adults feed opportunistically on vertebrates small enough to be engulfed. (Scott and Crossman 1973). Sight feeder.

Northern pike are important as top predators in the aquatic systems where they live.

Northern pike are top predators in the systems they inhabit. However, the eggs, fry, and young of northern pike may be eaten by other predatory fish, aquatic birds, otters, or by the larvae of aquatic insects.

In Great Britain and/or Ireland:
Animal / parasite / endoparasite
Acanthocephalus clavula endoparasitises anterior intestine of Esox lucius

Animal / parasite / ectoparasite
Argulus foliaceus ectoparasitises skin of Esox lucius

Animal / parasite / endoparasite
Cryptobia gurneyorum endoparasitises blood of Esox lucius

Animal / parasite / endoparasite
metacaria (diplostomula) of Diplostomum spathaceum endoparasitises eye (lens) of Esox lucius

Animal / parasite / ectoparasite / blood sucker
Piscicola geometra sucks the blood of Esox lucius

Animal / parasite / ectoparasite
fluke of Tetraonchus monenteron ectoparasitises gill of Esox lucius

Animal / parasite / endoparasite
Trypanosoma remaki endoparasitises blood of Esox lucius
Other: sole host/prey

Animal / parasite / endoparasite
metacaria of Tylodelphys clavata endoparasitises eye (humour) of Esox lucius

Esox lucius preys on:
Osmerus eperlanus mordax
Cyprinus carpio
Pimephales notatus
Stizostedion vitreum
Larus californicus

Based on studies in:
Quebec (Lake or pond, Pelagic)

This list may not be complete but is based on published studies.

Pike Fry Rhabdovirus. Viral diseases

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: This species is represented by a large number of occurrences (subpopulations).

>1,000,000 individuals

Comments: Total adult population size is unknown but very large.

Adults solitary except at spawning. Evidence from New England indicates that landlocked populations of Atlantic salmon may be negatively influenced as abundance of northern pike and/or ESOX hybrids increases.

Comments: Feeds diurnally. Active and feeds in winter under ice.

Spawners move inshore or upstream to the marsh areas to spawn (Ref. 27547). Generally, spawning occurs during the day. The sexes pair and a larger female is usually attended by one or two smaller males. They swim through and over the vegetation in water usually less than 17.8 cm, releasing eggs and sperm simultaneously at irregular intervals (Ref. 1998). Eggs are deposited in flooded areas and on submerged vegetation over a period of 2-5 days (Ref. 59043). Only 5 to 60 eggs ae released at a time (Ref. 27547). This act is repeated every few minutes for up to several hours, after which the fish rest for some time before resuming. During the resting period, both male and female may take new mates, or they may continue together for several days until all eggs are extruded. Spawned-out adults may stay on the spawning grounds for as long as 14 weeks, but most leave within 6 (Ref. 27547).

Northern pike can live up to 12 years.

Typical lifespan
Status: wild: 12 (high) years.

Average lifespan
Status: captivity: 10.0 years.

Average lifespan
Status: captivity: 6.8 years.

Average lifespan
Status: captivity: 10.0 years.

Average lifespan
Status: captivity: 6.8 years.

Average lifespan
Status: wild: 24.0 years.

Northern pike are considered random spawners not nest builders.

Mating System: polygynandrous (promiscuous)

Spawning occurs in the shallows when the water temperature reaches 4 to 7 degress Celsius (40-45 degrees Fahrenheit). Spawning lasts for 5 to 10 days after which the female leaves. Males remain in the spawning area for several weeks, but do not protect the eggs. At this stage the eggs are vulnerable to predators. The eggs that survive hatch in about 2 weeks. With their insatiable eating habits young Esox lucius grow rapidly in both length and weight. Males become sexually mature at 2 to 3 years-old and females at 3 to 4 years-old.

Breeding season: Spawning occurs in the spring.

Average time to hatching: 2 weeks.

Range age at sexual or reproductive maturity (female): 3 to 4 years.

Range age at sexual or reproductive maturity (male): 2 to 3 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Spawning lasts for 5 to 10 days after which the female leaves. Males remain in the spawning area for several weeks, but do not protect the eggs.

Parental Investment: no parental involvement; pre-fertilization (Provisioning)

Northern pike are considered random spawners not nest builders. Spawning occurs in the shallows when the water temperature reaches 4-7 degress Celsius (40-45 degrees Fahrenheit). Spawning lasts for 5 to 10 days after which the female leaves. Males remain in the spawning area for several weeks, but do not protect the eggs. At this stage the eggs are vulnerable to predators. The eggs that do survive hatch in about 2 weeks. With their insatiable eating habits young E. lucius grow rapidly in both length and weight. Males become sexually mature at 2-3 years-old and females at 3-4 years-old.

Breeding season: Spawning occurs in the spring.

Average time to hatching: 2 weeks.

Average age at sexual or reproductive maturity (female): 3-4 years.

Average age at sexual or reproductive maturity (male): 2-3 years.

Key Reproductive Features: fertilization (External ); oviparous

Average age at sexual or reproductive maturity (male)
Sex: male: 889 days.

Average age at sexual or reproductive maturity (female)
Sex: female: 1116 days.

Spawns in spring as soon as ice begins to break up. Produces a single clutch per year. Eggs hatch in 12-14 days at typically prevailing temperatures. Males sexually mature at 1-2 years in south, at age 5 in north; females mature at 2-3 years in south, at age 6 in north.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 78
Specimens with Barcodes: 119
Species With Barcodes: 1

Esox lucius is not currently threatened by extinction. The Departments of Natural Resources in states where they occur keep a close watch on population levels and can increase populations by stocking streams with Esox lucius raised in hatcheries.

IUCN Red List of Threatened Species: least concern

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Year Assessed

Assessor/s

Reviewer/s

Justification

Esox lucius is not currently threatened by extinction. The Departments of Natural Resources in states where they occur keep a close watch on population levels and can augment populations by stocking streams with Esox lucius raised in hatcheries.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Common

Global Short Term Trend: Relatively stable (=10% change)

Comments: Trend over the past 10 years or three generations is uncertain but likely relatively stable.

Population

Population Trend

Comments: No major threats are known.

Least Concern (LC)

Major Threats

Although pike need water high in oxygen and of low acidity, there does not appear to be any threats to population numbers in the UK. However, it is thought that over-fishing may be taking place in some other European countries (1999 figures).

Conservation Actions

Pike are a much-prized game fish and, in the UK, can be pursued by anglers throughout the season (16 June – 14 March), provided they hold a rod licence. There are no specific conservation measures currently in place for pike apart from general laws governing pollution of rivers and water bodies. Pike have been introduced into several countries' rivers to provide sport, and in some cases the fish have cause adverse ecological problems. Deliberately introducing pike to ponds in order to remove unwanted fish is a frequent practice in some areas and has to be monitored carefully.

There are no negative effects of northern pike on humans.

Esox lucius are prized game fish throughout their range and are a commercial food fish in eastern Europe.

Positive Impacts: food

fisheries: highly commercial; aquaculture: commercial; gamefish: yes; aquarium: public aquariums

There are no negative effects of northern pike on humans.

Esox lucius is a prized game fish throughout its range and is a commercial food fish in eastern Europe.

Positive Impacts: food

Comments: Highly prized game fish. Extensively cultured in Europe. (Sublette et al. 1990).

Species Impact: Where introduced, this fish can be a threat to native fish species.