Micropterus dolomieuBass(Also: Black bass; Bronzeback; Brown bass; Brown trout)

Geographic Range

The native range of Micropterus dolomieu encompasses the Great Lakes and the St. Lawrence seaway drainages from southern Quebec and New Hampshire to North Dakota, and the Mississippi River drainage as far south as Alabama (Page and Burr, 1998). It shares most of its range with the largemouth bass, Micropterus salmoides (Near et al., 2003). Beginning in 1873 with introduction to Belgium, the smallmouth bass has been introduced to South Africa, Scandinavia, the British Isles, France, Germany, The Czech Republic, Mexico, Belize, Austria, Slovakia, Vietnam, Guam, Fiji, and Hawaii (Welcomme, 1988). It has also been introduced to parts of the United States and Canada outside its natural range. (Near, et al., 2003; Page and Burr, 1998; Welcomme, 1988)


Although its native distribution overlaps much of the northern range of Micropterus salmoides, M. dolomieu typically is found in cooler rivers and lakes, with rocky or sandy substrates (Berra, 2001). As visual predators, smallmouth bass actively seek out clear waters (Sweka and Hartman, 2002). Increases in turbidity can cause displacement of many fish species, M. dolomieu included (Larimore, 1975). In lakes, smallmouth seek out structures, such as logs, rocky outcroppings, or pier posts (Etnier and Starnes, 1993). When present in stream ecosystems, they are typically found in areas with a relatively swift current (Probst et al., 1984). (Berra, 2001; Etnier and Starnes, 1993; Larimore, 1975; Probst, et al., 1984; Sweka and Hartman, 2003)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

Like all other species of the genus Micropterus, the smallmouth bass has a moderately compressed, elongate body. There are 3 spines in the anal fin, and 9-11 spines in the dorsal fin. Body is olive green above, yellow-white below, typically with 8-16 dark brown vertical bars on the side. The mouth is large, with the posterior edge of the maxilla extending to beneath the eye. Similar species include M. salmoides, M. punculatus, and M. coosae (Page and Burr, 1998). Average adult length ranges from 30-50 cm (15-20 in) (Mettee et al., 1996). Some populations have small tooth patches on the tongue (Etnier and Starnes, 1993). (Etnier and Starnes, 1993; Mettee, et al., 1996; Page and Burr, 1998)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    2975.5 g
    104.86 oz
  • Range length
    30 to 50 cm
    11.81 to 19.69 in


Larvae are typically 2.2-2.5 mm long at hatching. The notochord flexion occurs at a length of 6-9 mm. Dorsal and anal fins are typically completely formed by the time the fish has reached 7-13 mm. Fins form in the following sequence: soft-rayed dorsal, anal, spinous dorsal, pelvic, pectoral. Rays first appear in the approximate middle of the area the complete ray will encompass, and expand proximally and distally until reaching full size. The caudal fin is typically complete by the time the dorsal and anal fins have their full complement of soft rays. First scales appear towards the end of the larval period, when the fish is approximately 14-18 mm in length (Johnson 1983). (Johnson, 1983)


Like other centrarchids, the male will excavate and guard a small, round nest. Suitability for nest-building is maximized between 1-2.5 m in depth, with particle size of substrate near 30 mm (Clark et al., 1998). Several females may spawn in the nest of one male (Etnier and Starnes, 1993). Individual females may also spawn in the nests of several males. (Etnier and Starnes, 1993; Clark, et al., 1998; Etnier and Starnes, 1993)

When a female enters the male's territory, a complex dance occurs, with the pair rubbing and biting each other. The actual act of spawning occurs in about 5 seconds, and is repeated for up to 2 hours. Females lay upwards of 2,000 eggs at each spawning (Smith, 1979). After spawning is complete, the female is chased off, and will occasionally mate again with another male. The eggs hatch in 4-6 days, and the fry remain in the nest for approximately two weeks before dispersing (Neves, 1975; Scott and Crossman, 1998). (Neves, 1975; Scott and Crossman, 1973; Smith, 1979)

  • Breeding season
    Spawning typically occurs between March and May. Onset is based mainly on degree-days, when temperatures exceed 10°C (Shuter et al., 1980). In the extreme northern tail of its distribution, spawning may be delayed a month, and begin in April and run through June.
  • Range time to hatching
    2 to 3 days
  • Average time to independence
    2 weeks
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    3 to 4 years

Parental care in M. dolomieu is the sole responsibility of the male, who guards the eggs and fry for an extended length of time (Cooke et al., 2003a). Temperature variation of as little as 2°C can result in abandonment of the nest, especially when water temperature drops below 15°C (Rawson, 1945; Latta, 1963). (Cooke, et al., 2003a; Latta, 1963; Rawson, 1945)

  • Parental Investment
  • pre-fertilization
    • provisioning
  • pre-hatching/birth
    • protecting
      • male
  • pre-independence
    • protecting
      • male


Average life span is between 6 and 14 years (Carlander, 1977). (Carlander, 1977)

  • Range lifespan
    Status: wild
    26 (high) years
  • Typical lifespan
    Status: wild
    6 to 14 years


Smallmouth bass, like other black basses, may congregate around structural elements such as fallen logs or other large debris (Etnier and Starnes, 1993). (Etnier and Starnes, 1993)

Home Range

Smallmouth bass may have a range that extends for a few hundred yards. This will typically contain several large structures they will use as cover, darting between them as they traverse their territory (Etnier and Starnes, 1993). (Etnier and Starnes, 1993)

Communication and Perception

Smallmouth bass are highly visual predators; they require clear waters to be truly effective. Increasing turbidity decreases reactive distance significantly, ultimately reducing overall prey consumption. However, once a prey item has been reacted to, turbidity does not have an impact on capture success (Sweka and Hartman, 2003). (Sweka and Hartman, 2003)

Food Habits

Fry and juvenile diets consist primarily of zooplankton and insect larvae. Adults have a more diverse palate, subsisting on such varied foods as crayfish, amphibians, insects, and other fish (Scott and Crossman, 1973; Etnier and Starnes, 1993). Adults also cannibalize young of other parents (Scott and Crossman, 1973). (Etnier and Starnes, 1993; Scott and Crossman, 1973)

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


Although large adults are often the top predatory fish in their habitats, young adults and juveniles are often preyed upon by other fish (including other smallmouth bass) and turtles (Scott and Crossman, 1973). Osprey and kingfishers are known avian predators on adult and juvenile largemouth (Cooke et al., 2003b). These and similar birds are also known to eat smallmouth bass. (Cooke, et al., 2003b; Scott and Crossman, 1973)

Ecosystem Roles

Micropterus dolomieu often acts as a top predator in the systems it inhabits, primarily as a piscivore, but also taking a large proportion of macroinvertebrates. Young smallmouth are a major source of larval fish mortality (Etnier and Starnes, 1993). Smallmouth have been shown to reduce abundance of many small-bodied cospecifics, sometimes to the point of local extirpations (MacRae and Jackson, 2001). (Etnier and Starnes, 1993; MacRae and Jackson, 2001)

Economic Importance for Humans: Positive

An important sport fish throughout its range, the smallmouth is almost as popular as the largemouth bass. It is also a popular food fish (Scott and Crossman 1973). In many states, taxes on the sales of fishing rods and tackle, as well as proceeds from the sale of licenses contribute a large part of the budget for natural resource management organizations. (Scott and Crossman, 1973; Scott and Crossman, 1973)

Conservation Status

Micropterus dolomieu is not a conservation concern. Like M. salmoides, M. dolomieu is an important game fish. Each year, millions of dollars are spent by anglers in search of bass. Renowned for its fighting ability and tasty flesh, the smallmouth is fished for sport throughout its range (Etnier and Starnes, 1993). (Etnier and Starnes, 1993)

Other Comments

The genus name Micropterus is Greek, meaning "little fin". The species name "dolomieu" recognizes Comte Déodat de Dolomieu.

Micropterus dolomieu was originally described by Lacepède, who named the species in 1802. (Mettee, et al., 1996)


John Whitlock (author), University of Michigan-Ann Arbor, William Fink (editor, instructor), University of Michigan-Ann Arbor, Renee Sherman Mulcrone (editor).



living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map


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.

World Map


living in the southern part of the New World. In other words, Central and South America.

World Map


living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

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.


an animal that mainly eats meat


uses smells or other chemicals to communicate


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.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


A substance that provides both nutrients and energy to a living thing.


mainly lives in water that is not salty.


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.


An animal that eats mainly insects or spiders.


referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

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.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)


an animal that mainly eats fish


an animal that mainly eats plankton


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


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).


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight to communicate


animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)


Berra, T. 2001. Freshwater Fish Distribution. San Diego, CA: Academic Press.

Carlander, K. 1977. Handbook of freshwater fishery biology. Volume 2: Life history data on centrarchid fishes of the United States and Canada. Ames, IA: Iowa State University Press.

Clark, M., K. Rose, J. Chandler, T. Richter, D. Orth, W. Van Winkle. 1998. Simulating smallmouth bass reproductive success in reservoirs subject to water level fluctuations. Environmental Biology of Fishes, 51: 161-174.

Cooke, S., J. Schreer, D. Philipp, P. Weatherhead. 2003. Nesting activity, parental care behavior, and reproductive success of smallmouth bass, Micropterus dolomieu, in an unstable thermal environment. Journal of Thermal Biology, 28(6-7): 445-456.

Cooke, S., J. Steinmetz, J. Degner, E. Grant, D. Philipp. 2003. Metabolic fright responses of different-sized largemouth bass (Micropterus salmoides) to two avian predators show variations in nonlethal energetic costs. Canadian Journal of Zoology, 81(4): 699-709.

Etnier, D., W. Starnes. 1993. The Fishes of Tennessee. Knoxville, TN: University of Tennessee Press.

Johnson, G. 1983. Percoidei: Development and Relationships. Ontogeny and Systematics of Fishes, American Society of Ichthyologists and Herpetologists, Special Publication 1: 464-498.

Larimore, R. 1975. Visual and tactile orientation of smallmouth bass fry under floodwater conditions. Pp. 323-332 in R Stroud, H Clepper, eds. Black Bass Biology and Management. Washington, D.C.: Sport Fishing Institute.

Latta, W. 1963. The life history of the smallmouth bass, Micropterus d. dolomieui, at Wagoshance Point, Lake Michigan. Bulletin, Institute of Fisheries Research, Michigan Department of Conservation, 5.

MacRae, P., D. Jackson. 2001. The influence of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages. Canadian Journal of Fisheries and Aquatic Sciences, 58(2): 342-351.

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

Near, T., T. Kassler, J. Koppleman, C. Dillman, D. Philipp. 2003. Speciation in North American black basses, Micropterus (Actinopterygii: Centrarchidae). Evolution, 57(7): 1610-1621.

Neves, R. 1975. Factors affecting fry production of smallmouth bass (Micropterus dolomieui) in South Branch Lake, Maine. Transactions of the American Fisheries Society, 104: 83-87.

Page, L., B. Burr. 1998. A Field Guide to Freshwater Fishes : North America North of Mexico. New York: Houghton-Mifflin.

Probst, W., C. Rabeni, W. Covington, R. Marteney. 1984. Resource use by stream-dwelling rock bass and smallmouth bass. Transactions of the American Fisheries Society, 90: 125-129.

Rawson, D. 1945. The experimental introduction of smallmouth black bass into lakes of the prince Albert National Park, Saskatchewan. Transactions of the American Fisheries Society, 73: 19-31.

Scott, W., E. Crossman. 1973. Freshwater Fishes of Canada. Bull. Fish. Res. Board Can., 184: 1-966.

Shuter, B., J. MacLean, F. Fry, H. Regier. 1980. Stochastic simulation of temperature effects on first-year survival of smallmouth bass. Transactions of the American Fisheries Society, 109: 1-34.

Smith, P. 1979. The Fishes of Illinois. Urbana, Ill.: University of Illinois Press.

Sweka, J., K. Hartman. 2003. Reduction of reactive distance and foraging success in smallmouth bass, Micropterus dolomieu, exposed to elevated turbidity levels. Environmental Biology of Fishes, 67: 341-347.

Welcomme, R. 1988. International introductions of inland aquatic species. FAO Fisheries Biology Technichal Papers, 294: 1-328.