Geographic Range
This species is native to lakes and streams in the St. Lawrence, Great Lakes, and Mississippi River systems.
Thus, it ranges from Quebec to northern Mexico. However, it has been introduced widely
in places such as Hawaii, Africa, Asia, South America, and Europe.
- Biogeographic Regions
- nearctic
- palearctic
- oriental
- ethiopian
- neotropical
- oceanic islands
Habitat
Bluegill prefer to live in lakes and slow-moving, rocky streams. They can often be
found in deep beds of weeds. In Hawaii they primarily inhabit reservoirs. Though
they are freshwater fish, they can tolerate salinities up to 18% and are present in
tributaries of the Chesapeake Bay.
- Habitat Regions
- temperate
- freshwater
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- Wetlands
- marsh
Physical Description
Like other sunfish, bluegill have very deep and highly compressed bodies. In other words, they are "tall" and "flat." They have a small mouth on a short head. The dorsal fin is continuous, with the front part spiny and the back part soft and round with a dark smudge at the base. The tail fin is slightly forked but rounded. The body is mainly olive green with yellowish underneath. Their name "bluegill" comes from the iridescent blue and purple region on the cheek and gill cover (opercle). A close look reveals six to eight olive-colored vertical bars on the sides.
Typically, adults are between 10 and 15 cm but they can grow as large as 41 cm.
Young bluegill are a paler version of the adults, usually silver with a slight purple
sheen.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
Reproduction
Males make nests in colonies with from 20 to 50 other males in shallow water less than 1 m deep. The nests are circular shallow depressions, about 20 to 30cm in diameter, in sand or fine gravel from which the male has fanned all debris (Murdy et al., 1997).
Once his nest is made, a male waits in it and grunts to attract females. When one enters, both male and female swim in circles. Eventually they stop and touch bellies, the male in an upright posture and the female leaning at an angle. They release eggs and sperm and then start the process again by swimming in circles.
A female deposits her eggs into several nests, and a male's nest may be used by several
females (Williams, 1996).
- Mating System
- polygynandrous (promiscuous)
Spawning occurs when water is between 17 and 31 degrees C; in the Chesapeake Bay area
it can begin when water temperatures reach 12 degrees C. Females can carry up to
50,000 eggs which take several days to hatch. After a week, young leave the nest.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
Males guard nests both before and after females lay eggs. Paternal care involves
fanning the eggs and chasing away predators.
- Parental Investment
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
protecting
- male
-
protecting
Lifespan/Longevity
Bluegill typically live 4 to 6 years but can reach 8 to 11 years old in captivity.
Behavior
Bluegill are most active at dawn. During the day they stay hidden under cover, and
they move to shallow water to spend the night. Schools may contain 10 to 20 fish.
- Key Behaviors
- natatorial
- crepuscular
- motile
- sedentary
- social
Home Range
Communication and Perception
Males change color during breeding season so it seems likely that visual cues are important either to other males or to females. Grunting is involved in courtship.
Food Habits
The very small mouth of this fish is an adaptation to eating small animals. Bluegills
are carnivores, primarily eating invertebrates such as snails, worms, shrimp, aquatic
insects, small crayfish, and zooplankton. They can also consume small fish such as
minnows and plant material such as algae. Young bluegill eat worms and zooplankton,
staying under cover while adults feed more in the open.
- Primary Diet
-
carnivore
- eats non-insect arthropods
- Animal Foods
- fish
- insects
- mollusks
- aquatic or marine worms
- aquatic crustaceans
- zooplankton
- Plant Foods
- algae
Predation
Bluegill travel in schools and come into shallow water only at night. During the
day they try to remain hidden.
Ecosystem Roles
Bluegill are an important prey species for larger fish predators. They also impact insect populations by eating aquatic larvae.
Economic Importance for Humans: Positive
This is an important game fish in the United States. Bluegill are fairly easy to
catch and are good to eat. They are also used to stock rivers and lakes with food
for
largemouth bass
, another important game fish.
- Positive Impacts
- food
- ecotourism
Economic Importance for Humans: Negative
Several countries where this species has been introduced report that it causes ecological
problems. Bluegill overcrowd and stunt the growth of other fish and may even be responsible
for causing extinction of a native fish in Panama. It is considered a pest in its
introduced range.
Conservation Status
Bluegill are abundant in their native range. Many individuals are raised in aquaculture
facilities and used to stock waterways.
Additional Links
Contributors
Cynthia Sims Parr (author), University of Michigan-Ann Arbor.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- oceanic islands
-
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- freshwater
-
mainly lives in water that is not salty.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- natatorial
-
specialized for swimming
- crepuscular
-
active at dawn and dusk
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- social
-
associates with others of its species; forms social groups.
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- zooplankton
-
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
- food
-
A substance that provides both nutrients and energy to a living thing.
- ecotourism
-
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
- carnivore
-
an animal that mainly eats meat
References
Conservation Commission of Missouri, 2002. "Bluegill fishing in Missouri" (On-line). Accessed 26 March 2002 at http://www.conservation.state.mo.us/fish/fishid/bluegill/ .
Froese, R., D. Pauly, eds.. 2002. "FishBase: Lepomis macrochirus" (On-line). Accessed 26 March 2002 at http://www.fishbase.org .
Murdy, E., R. Baker, J. Musick. 1997. Fishes of Chesapeake Bay . Washington, D.C.: Smithsonian Institution Press.
Williams, T. 1996. "Fish capsule report: Lepomis macrochirus" (On-line). Accessed 26 March 2002 at http://www.umich.edu/~bio440/fishcapsules96/Lepomis.html .