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Grass pickerel

Esox americanus

What do they look like?

This fish is an esocid. It has fully scaled cheeks and gill covers, and the top of the head has few or no scales. A darkened backward slanting vertical bar is present beneath the eyes. The dorsal side is dark green to brown, and the ventral side is cream or yellow. The color patterns on the lateral sides is variable, from a green and white brick wall pattern to forward slanting vertical bars (Mettee, et al., 1996). E. americanus can occasionally grow longer than 12 inches (Florida Fish and Wildlife, 2000).

Some key physical features:

ectothermic; heterothermic.

Sexual dimorphism:

sexes alike.

What kind of habitat do they need?

This species is most often found in clear lakes and slow to moderate running streams, but can also be found in overflow pools and marshes. Their habitat includes dense aquatic vegetation and bottoms with organic matter. The preferred temperature of this fish is 26° C. The highest population densities are found in shallow weedy areas with lots of vegetation including leafy liverworts, water lilies, filamentous algae, pondweeds, and cattails (Wallus, et al., 1990).

Aquatic Biomes:

lakes and ponds; rivers and streams.

How do they reproduce?

Depending on the location of the fish, spawning will take place anywhere from late February to early May, with fish in warmer climates spawning earlier than those in colder climates. E. americanus is one of the earliest spawning fishes in the spring. To spawn, the fish migrate from large rivers and lakes into small streams. Spawning temperature has been estimated at anywhere from 4°C to 18.3°C (Wallus, et al., 1990).

The act of spawning occurs with one female and several males. Eggs and milt are ejected by sudden lashings of the caudal fin. Eggs are broadcast over aquatic vegetation, moss, leaves, twigs, and in temporary floodplains, marshes and shallow pools (Wallus et al., 1990). The incubation period of the eggs lasts from 11 to 15 days, longer incubation is needed for eggs to mature in colder water.

Key reproductive features:

seasonal breeding; sexual; oviparous.

How do they behave?

Young live in schools while adults are solitary, predaceous, and aggressive, only coming together to spawn (Mettee, 1996).

What do they eat?

E. americanus is a predator that as an adult feeds on large insect larvae, crayfishes and other fishes. This fish does not move a great deal to hunt for food. Instead it camouflages itself and waits for unsuspecting prey. When it has the prey located, it will dart out of hiding quickly, grasp the prey and swallow it head first (Mettee, et al., 1990). Newly hatched larvae feed on larvae of later spawning species.

Primary Diet:

carnivore (piscivore, insectivore, eats non-insect arthropods).

Animal Foods:

fish; insects; aquatic crustaceans.

How do they interact with us?

It can be fun to fish for Esox americanus, but because they do not grow very large, they are not popular as a sport fish. The meat from these fish is white, flaky, and sweet, but bony (Florida Fish and Wildlife, 2000).

Are they endangered?

US Federal List:

No special status.

State of Michigan List:

No special status.

Esox americanus is a common species with a wide geographic range. It is not threatened or endangered.

Some more information...

There are two subspecies of E. americanus. They are E. americanus americanus, commonly known as the redfin pickerel, and E. americanus vermiculatus, known better as the grass pickerel. These subspecies are very similar and do breed together where their ranges overlap. Redfin pickerel live to six years, and grass pickerel live to seven years (Mettee, 1996).

Contributors

Sera Coppolino (author), University of Michigan: November, 2000.

William Fink (editor), University of Michigan.

References

Florida Fish and Wildlife Conservation Commission, "Pickerel" (On-line). Accessed November 10, 2000 at http://www.state.fl.us/gfc/fishing/Fishes/pickerels.html.

Mettee, M., P. O'Neil, J. Pierson. 1996. Fishes of Alabama and the Mobile Basin. Birmingham, Alabama: Oxmoor House.

Wallus, R., T. Simon, B. Yaeger. 1990. Reproductive Biology and Early Life History of Fishes in the Ohio River Drainage. Volume 1: Acipenseridae through Esocidae. Chattanooga, Tennessee: Tennessee Valley Authority.

 
University of Michigan Museum of Zoology National Science Foundation

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BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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