Esox niger

Geographic Range

Esox niger , also known as chain pickerel, is native to freshwaters of eastern North America. Their main native range is on the Atlantic slope, from southern Maine south to Florida and in freshwater drainages along the northern shore of the Gulf of Mexico, from Florida west to east Texas, including the lower Mississippi. The species has been introduced into the St. Lawrence River and eastern Great Lakes, and into New Brunswick and Nova Scotia, as well as a few drainages in the western United States.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native

Habitat

Chain pickerel are found in a wide variety of freshwater habitats, such as lakes, streams, swamps and ponds, and are most abundant in calm, sluggish, clear water. They have been known to migrate into brackish waters of up to 22% salinity in the wintertime. However, it is more common to find them in waters with salinity levels of less than 5%. Juveniles spend the majority of their time in the shallows, while adults spend most of their day in deeper water of up to three meters and wait for nightfall to move into shallow water. These pickerel are commonly found near some kind of submerged cover, like brush, logs, or aquatic vegetation.

• Habitat Regions
• temperate temperate
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• brackish water brackish water

• Wetlands
• swamp swamp

Physical Description

Chain pickerel are long and slender fish that are predominately olive or yellowish-green. These pickerel have a pattern of ovals surrounded by a darker brown outline that runs the length of their lateral surfaces. Their ventral surface is pearl white, while their dorsal surface fades to a darker color, much like the lining of the ovals on their sides. Chain pickerel have elongated and narrow snouts, which are often compared to duck bills. Their opercles, or gill covers, are fully scaled. They are known to be ectotherms. These fish have seven fins, none of which are spotted. They have paired pectoral fins, paired pelvic fins, a dorsal fin, anal fin, and a caudal fin. The fins carry a slightly darker color than their body, and sometimes have a slight red tint. Adult chain pickerel generally weigh between 198 grams and 1.4 kilograms, and measure between 30.5 and 67.1 cm in length. However, they have been known to reach masses of up to 2.84 kg. There is no significant difference between the size of male and female adult chain pickerel. One-year-old pickerel measure between 7.6-20 cm in length. These young fish typically have darker bars running along their ventral and lateral surfaces, but the chain-like pattern seen in adults is still evident. Adults are often confused with redfin pickerel Esox americanus . However, one can distinguish between the two by the chain pickerels’ longer snout and repeating chain-like pattern.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

Female chain pickerel swim around with one or two males until they simultaneously release eggs and sperm into submerged vegetation. These somewhat sticky eggs are about 2 mm in diameter, and take six to twelve days to hatch. While the young pickerel are able to swim immediately upon hatching, they are normally inactive until they absorb their yolk sac 6-8 days later. These hatchlings, averaging 10.2 mm, then begin to opportunistically feed and start to grow. Young chain pickerel grow rapidly under the suitable conditions (i.e. when food is not a limiting factor), but a study conducted in New York found that this growth greatly varies from year to year (Underhill, 1949). Chain pickerel reach sexual maturity by age four. Underhill (1949) reported that the average length of one-year-old chain pickerel was 18 cm. The average length gradually increased to about 50 cm in both males and females at age five, with the largest change in length occurring between ages three and four.

Reproduction

Chain pickerel are known to be monogamous or polyandrous. During spawning season, one or two male chain pickerel will join a female in shallow vegetation and swim alongside her for 1-2 days. They eventually deposit their sperm and eggs simultaneously and mix them together by quick movements of their tails.

• Mating System
• monogamous monogamous
• polyandrous polyandrous

Chain pickerel spawn once a year between December and May, with southern populations (e.g. Florida) breeding earlier than northern populations. The spawn generally occurs when water temperatures are between 2-22°C, with the peak of activity occurring between 8.3-11.1°C. A population of fish generally will spawn over a 7-10 day period when temperatures for that particular body of water are ideal. When these temperatures are close to being reached, chain pickerel will move out of deeper water wintering locations and into sluggish, vegetated waters with depths up to 3 meters. One or two males will swim alongside a single female for a 1-2 day period. The females will then release their eggs and the males release sperm simultaneously into the vegetation. The parents then mix their eggs and sperm with powerful tail motions. Females have been known to lay up to 50,000 eggs at a time, but 6,000-7,000 eggs are more common. The parents then abandon the eggs, and are done spawning for the year. Fertilized eggs average 2-3 mm in diameter, and take between 6-12 days to hatch. The young pickerel emerge in individual yolk sacs, and absorb them in 6-8 more days. At this time, the fry average 10 mm in length, and begin to feed, hide from predators, and rapidly grow. Both sexes reach sexual maturity between one and four years of age.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• broadcast (group) spawning
• oviparous oviparous

After male and female chain pickerel mix their sperm and eggs, they provide no further parental care.

• Parental Investment
• no parental involvement
• pre-fertilization
  • provisioning

Lifespan/Longevity

The average lifespan for male and female chain pickerel is 3-4 years in the wild. They have been known to live up to nine years in the wild, and are not commonly kept in captivity.

Behavior

Chain pickerel can be active at any time of day and are not considered nocturnal or diurnal. However, they are generally more active in the early morning and late afternoon when they are actively feeding. Like northern pike, Esox lucius , chain pickerel are solitary fish, although they have been observed engaging in cannibalistic activity when food is sparse. Males and females also tolerate one another in the spawning season, while one or two males swim alongside a single female through submerged vegetation, waiting to deposit their eggs and sperm. After the pickerel hatch and absorb their yolk sacs 6-8 days later, they begin feeding like more mature pickerel. They hide out in underwater cover while waiting to ambush small forms of aquatic life (e.g. minnows, insects, crayfish). Adults commonly ambush their larger sized prey in a similar fashion. Chain pickerel choose the depth of water they reside in based on time of year. In the spring, summer and fall, they are usually found in water up to 3 meters deep. In the winter, they commonly migrate into deeper water, often in search of baitfish.

• Key Behaviors
• natatorial natatorial
• motile motile
• migratory migratory
• solitary solitary

Home Range

Northern pike, Esox lucius , a member of the same genus, are known to establish home ranges based upon time of year. They typically can be found in shallow water with vegetated bottoms in the spring and summer, while in the fall it is more common to find them near rocky banks. During winter, the majority of pike migrate back to their summer habitats. However, larger pike require a greater food supply and will spend this season in deeper water in close proximity to baitfish such as shad Dorosoma . It’s likely that chain pickerel have similar habits and occupy similar home ranges.

Communication and Perception

Chain pickerel have lateral lines, composed of sensory organs, that they use to acclimate themselves to their environment and to sense when other fish are nearby. Members of the same genus, northern pike ( Esox lucius ), are known to defecate away from their home area. One proposed hypothesis for this habit is that minnows may be able to sense their risk of becoming prey from the chemosensory cues present in the northern pike’s feces. This would force pike to expend more energy in search of the minnows. Another hypothesis suggests that northern pike localize their defecation in order to mark their territorial boundaries, and a third suggests that the defecation allows for the recognition of group members. It is likely that chain pickerel have similar communication pathways. Muskellunge ( Esox masquinongy ), are visually oriented when displaying predatory behavior. New et al. (2001) found that vision plays a vital role in locating prey, and beginning their attack approach. Nilsson (2008) claims that northern pike ( Esox lucius ) also primarily rely on vision for feeding. It is likely that chain pickerel rely heavily on visual cues as well.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• vibrations vibrations
• chemical chemical

Food Habits

Chain pickerel are predators that generally reside near the top of the food chain. As adults their main prey are smaller fish, but have also been known to opportunistically feed on other vertebrates such as frogs, snake and small mammals, and both juveniles and adults feed on insects. Small crustaceans make up another portion of their diet, as do other chain and redfin pickerel ( Esox americanus ). Chain pickerel commonly ambush their prey, and tend to hide out near submerged cover while they wait. Larger chain pickerel generally eat larger prey, and they continue feeding throughout the winter season. Raney (1942) studied chain pickerel in a New York pond and found that golden shiners ( Notemigonus crysoleucas ) were found in the stomachs of 47.3% of the 234 chain pickerel examined. Common bullheads ( Ameiurus nebulosus ) were found in 13.8%, and common sunfish ( Lepomis gibbosus ) were found in 13.2%. Crayfish ( Cambarus ) were present in 42% of the chain pickerel.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • insectivore insectivore
  • eats non-insect arthropods

• Animal Foods
• amphibians
• reptiles
• fish
• insects
• aquatic crustaceans

Predation

Adult chain pickerel have very few predators. They have been known to act cannibalistically; larger chain pickerel and other members of the Esox genus such as northern pike, Esox lucius and muskellunge, Esox masquinongy , will feed on smaller, young pickerel. These juvenile fish commonly hide from predators by burying themselves in mud or vegetation and remaining motionless, attempting to blend into their surroundings. In the southern portion of the species range, large piscivores such as alligators ( Alligator mississippiensis and large gars ( Atractosteus spatula , possibly Lepisosteus osseus ) might prey on adult chain pickerels. Humans, Homo sapiens , also are predators of these fish. Pickerel are a popular game species among anglers, who fish for them year-round. They are commonly caught and released, but some anglers may choose to eat them. Others may die if they are hooked deeply by a fishing hook or improperly handled.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Chain pickerel are secondary or sometimes tertiary consumers. In smaller freshwater habitats that may be top-level predators. They may affect prey populations and certainly affect prey behavior.

Chain pickerel can become hosts to many parasites. The protozoans include Henneguya esocis , Henneguya nigris , Trichodina renicola , and Trypanosoma remaki . The trematodes include Azygia acuminata , Azygia angusticauda , Azygia longa , Azygia sebago , Bucephalus elegans , Clinostomum marginatum , Crassiphiala bulboglossa , Crepidostomum cooperi , Diplostomulum scheuringi , Macroderoides flavus , Macroderoides spiniferus , Microphallus opacus , Microphallus ovatus , Phyllodistomum superbum , Urocleidus mimus , and Uvulifer ambloplitis . The cestodes include Proteocephalus ambloplitis , Proteocephalus nematosoma , Proteocephalus pinguis , Proteocephalus sp ., and Triaenophorus nodulosus . The nematodes include Hedruris tiara , Philometra , Raphidascaris , Spinitectus gracilis , and the members of the family Spiruridae . The acanthocephalans include Leptorhynchoides thecatus , Neoechinorhynchus cylindratus , Neoechinorhynchus cylindratus , and Neoechinorhynchus tenellus . The parasitic crustaceans include fish lice, Argulus versicolor .

Economic Importance for Humans: Positive

Chain pickerel are popular game fish. These fish are edible, aggressive on the line, and anglers can catch them on both artificial lures and live bait. Also, chain pickerel are active throughout the winter, and can be caught year-round.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

When introduced outside their native range in eastern Canada, chain pickerel have been found to reduce the diversity of native fish species by preying on them. Other than that, there are no known adverse effects of chain pickerel on humans.

Conservation Status

The IUCN rates chain pickerel are a species of “Least Concern,” and the species is not listed under the U.S. Endangered Species Act or on the CITES treaty. Chain pickerel are popular sport fish and are sometimes harvested for food, so some U.S. states put limits on the number that may be harvested. Stocking efforts have taken place in some locations throughout Canada and the United States. This has expanded the chain pickerels’ range, and has also helped to keep their population stable.

Additional Links

Encyclopedia of Life

Contributors

Jacob Shelburne (author), Radford University, Karen Powers (editor), Radford University, Alex Atwood (editor), Radford University, Marisa Dameron (editor), Radford University, George Hammond (editor), Animal Diversity Web Staff.

References

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