The smallmouth bass (Micropterus dolomieu) is freshwater fish in the sunfish family (Centrarchidae). The seven species in genus Micropterus are known as the black basses. Micropterus dolomieu is the type species of its genus, and can be distinguished from its congenitor, the large mouth bass, (M. salmoides) by the feature that the back end of its lower jaw does not extend past its eye orbit. Smallmouth bass are also known as bronzeback, brown bass, brownie, smallie, bronze bass, and bareback bass. Native to the great lakes region, the smallmouth bass is a popular game fish throughout temperate North America, as a strong fighter with good tasting flesh. It has been spread as a recreational stock fish to many cool-water tributaries and lakes in the United States and Canada, and also throughout the world. Smallmouth bass mature at three to four years of age. Anglers usually catch fish 8 to 15 inches long and weighing less than three pounds, however, the current world record was caught at Dale Hollow Reservoir in 1955, weighing in at 11 lbs, 15 oz.

(Michigan Department of Natural Resources 2011; Wikipedia 2011; Wikipedia 2012)

Inhabit shallow rocky areas of lakes, clear and gravel-bottom runs and flowing pools of rivers, cool flowing streams and reservoirs fed by such streams (Ref. 1998). Young feed on plankton and immature aquatic insects while adults take in crayfish, fishes, and aquatic and terrestrial insects (Refs. 1998, 10294, 44091). Sometime cannibalistic (Ref. 30578). Preyed upon by fishes and turtles (Ref. 1998). Excellent food fish (Ref. 1998).

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.

Biogeographic Regions: nearctic (Introduced , Native ); palearctic (Introduced ); ethiopian (Introduced ); neotropical (Introduced ); oceanic islands (Introduced )

occurs (regularly, as a native taxon) in multiple nations

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

Global Range: Smallmouth bass is native to the St. Lawrence-Great Lakes, Hudson Bay (Red River), and Mississippi River basins from southern Quebec to North Dakota and south to northern Alabama and eastern Oklahoma. It has been widely introduced throughout the United States, southern Canada, and other countries.

North America: St. Lawrence-Great Lakes system, Hudson Bay and Mississippi River basins from southern Quebec in Canada to North Dakota and south to northern Alabama and eastern Oklahoma in the USA. Introduced into many countries for sport fishing. Several countries report adverse ecological impact after introduction.

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).

Range length: 30 to 50 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes alike

Average mass: 2975.5 g.

Dorsal spines (total): 911; Dorsal soft rays (total): 1315; Analspines: 1011; Vertebrae: 31 - 32

Length: 69 cm

Maximum size: 690 mm TL

69.0 cm TL (male/unsexed; (Ref. 5723)); max. published weight: 5,410 g (Ref. 4699); max. reported age: 26 years (Ref. 46974)

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).

Habitat Regions: temperate ; tropical ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams

Depth range based on 83 specimens in 2 taxa.

Environmental ranges
  Depth range (m): 0.05 - 15

Graphical representation

Depth range (m): 0.05 - 15
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Freshwater

Comments: Smallmouth basses prefer large clear lakes (especially in the northern part of the range) and clear midorder streams with many large pools, abundant cover (rocks, shelves, logs, etc.), and cool summer temperatures. Adults seek shelter of pools or deep water during day.

Spawning habitat includes shallow water in lakes or quiet areas of streams, often fairly close to shore. Lake populations may move a short distance up a stream to spawn. Females deposit eggs in nests made by males, usually near cover on gravel or sand bottoms. Individual males may nest close to the previous year's nest site(Ridgway et al. 1991).

benthopelagic; freshwater

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 short distances between spawning and nonspawning habitats (Moyle 1976).

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).

Animal Foods: amphibians; fish; insects; aquatic crustaceans; zooplankton

Plant Foods: phytoplankton

Primary Diet: carnivore (Piscivore , Insectivore , Eats non-insect arthropods); planktivore

Inhabits shallow rocky areas of lakes, clear and gravel-bottom runs and flowing pools of rivers, cool flowing streams and reservoirs fed by such streams. Young feed on plankton and immature aquatic insects while adults take in crayfish, fishes, and aquatic and terrestrial insects (Refs. 1998; 44091). Sometime cannibalistic (Ref. 30578). Preyed upon by fishes and turtles (Ref. 1998). Feeds on fish and benthic invertebrates (Ref. 26273).

Comments: Fry eat mainly crustaceans and aquatic insects (e.g., chironomid larvae and pupae) until they are about 5 cm TL, when they start feeding heavily on fishes. Crayfish, amphibians, and insects often become dominant foods of local populations or seasonally. Adults almost entirely piscivorous if sufficient prey available.

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).

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.

Known Predators:

• fish (Actinopterygii)
• turtles (Testudines)
• osprey (Pandion haliaetus)
• kingfishers (Alcedininae)

Micropterus dolomieu preys on:
Lepomis megalotis
Etheostoma caeruleum
Gallinula chloropus

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

Usually stays within 5 miles of place of original capture, but longer movements have been recorded (Scott and Crossman 1973).

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).

Communication Channels: tactile ; chemical

Perception Channels: visual

Comments: In the warmer months, smallmouth bass are most active at dusk and dawn. In the northern part of the range, smallmouth basses are relatively inactive in winter (Becker 1983).

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).

The male builds the nest in shallow waters of lakes and rivers, on sand, gravel, or rocky bottoms. Nest building usually occurs within 150 yards of where his nest was built in previous years. The pair swims about the nest, rubbing and nipping each other and eventually come to rest on the bottom. Actual spawning occurs and lasts for 5 seconds. The pair then encircles the nest for about 25-45 seconds, before settling to spawn again. This goes on for 2 hours. After spawning, the female leaves the nest and may spawn with another male in another nest. Males guard the eggs and young. (Ref. 1998).

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

Range lifespan

Status: wild: 26 (high) years.

Typical lifespan

Status: wild: 6 to 14 years.

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.

Mating System: polygynandrous (promiscuous)

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).

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.

Key Reproductive Features: seasonal breeding ; sexual ; fertilization (External ); broadcast (group) spawning; oviparous

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).

Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Protecting: Male); pre-independence (Protecting: Male)

Spawning occurs in late spring or early summer and may be interrupted by flooding. Eggs hatch in 2-10 days at 60-77°F (15-25°C). Males guards eggs and hatchlings. Fry leave the nest about 10-15 days after egg deposition. Parental care may last 4 weeks or longer. Individuals usually attain sexual maturity at age II in south, age VI in north (Moyle 1976, Becker 1983). Nests are solitary rather than colonial.

The following is a representative barcode sequence, the centroid of all available sequences for this species. 

 
There are 34 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
 

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 34
Species: 64
Species With Barcodes: 1

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).

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Not Evaluated

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.

Positive Impacts: food ; ecotourism

Comments: Relatively infrequently cultured.

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

Species Impact: Introduced populations may negatively impact native frogs. Kiesecker and Blaustein (1998) found that R. AURORA was negatively impacted when exposed to the combined effects of bullfrog larvae and adults or bullfrog larvae and smallmouth bass.

Comments: Introductions of this species have led to hybridization with Guadalupe bass (Whitmore 1983). Has hybridized with spotted bass in Missouri (Koppleman, Copeia 1994:204-210).

Robins et al. (1991) emended the specific name dolomieui to the original spelling, dolomieu. This change conforms with the policies of the 1985 International Code of Zoological Nomenclature and has been followed in recent major ichthyological publications (e.g., Etnier and Starnes 1993, Jenkins and Burkhead 1994).