Fish and Aquatic Conservation

illustration of a Smallmouth bass

Smallmouth bass

Micropterus dolomieu, (Lacepiede, 1802)

Cool Facts

It normally takes three to five years of growth before smallmouth bass are legally harvestable in states that have a minimum recreational size limit of 12 inches. The oldest reported age for smallmouth bass is 26 years. The heaviest reported weight for a smallmouth bass is 5.4 kg (11 lbs., 15 oz.)

SIZE: The length of smallmouth bass most commonly caught is between 12 and 16 in (30.5 cm to 40.6 cm). The maximum recorded length for a smallmouth bass is 27.2 in (69 cm). Generally, male smallmouth bass are smaller than female smallmouth bass.

RANGE: The range of smallmouth bass in North America includes the St. Lawrence Seaway to the Great Lakes systems and Hudson Bay. Their range extends from southern Quebec in Canada to North Dakota and south to northern Alabama and eastern Oklahoma within the U.S. They are also present in the drainages of the Mississippi river basins. Smallmouth bass have also been introduced into England, Europe, Japan, Russia and into Africa.

HABITAT: Adult smallmouth bass live in shallow rocky areas of lakes and in the clear and gravel bottom runs and flowing pools of rivers. They also live in cool flowing streams and reservoirs fed by these types of streams.

DIET: Young smallmouth bass feed on plankton and immature aquatic insects. Smallmouth bass are also known to be cannibalistic. Adult smallmouth bass may feed on crayfish, fish and aquatic and terrestrial insects.

Natural History

When reproducing , male smallmouth bass build spawning nests just like their largemouth cousins in the shallow waters of lakes and rivers, on sand, gravel, or rocky bottoms. Nest building occurs within 150 yards of where the male smallmouth bass built his nest the previous year.

The mating smallmouth pair (male and female) swim above the nest, rubbing against each other and then rest on the bottom of the nest. While resting on the bottom, spawning occurs and lasts for five seconds. The spawning pair will then encircle the nest from between 25 to 45 seconds before preparing to spawn again. This paired spawning ritual can continue for up to two hours.

After completing this ritual the female will leave the nest and might spawn with another male smallmouth bass. Only a fraction of adult males build nests and only a fraction of adult females spawn. The remaining male will stay and guard the nest until the eggs hatch which is usually within four to seven days and will remain on the nest until the young fry are ready to leave the nest.


Smallmouth bass are a popular recreational species in the United States. State fish and wildlife agencies manage smallmouth bass by conserving and protecting smallmouth habitat, installing nesting cover in their habitat, stocking, and using various recreational fishing regulations to control the harvest of smallmouth bass. The National Fish Hatchery System and the Fish and Wildlife Conservation Offices of the U.S. Fish and Wildlife Service assist the States in managing America’s smallmouth bass resources.

Smallmouth bass have been introduced into many countries for recreational fishing purposes. Several countries have reported negative impacts from the introductions of smallmouth bass.