Micropterus dolomieu
smallmouth bass

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)

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, O'Neil, and Pierson, 1996; Page and Burr, 1998)

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)

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

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)

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)

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)

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)

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)

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)

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)

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, O'Neil, and Pierson, 1996)