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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Largemouth Bass

Taxonomy: available through www.itis.gov

Identification: The Largemouth Bass (Micropterus salmoides) has an elongate body that ranges in color from a silvery-white to brassy-green and occasionally to a light brown in darker water. It is camouflaged with a dark olive mottling on its dorsal surface, a broad black stripe (typically broken into a series of blotches), and greenish-black speckles along its side. The caudal fin has a dusky black edge which is most prominent in juveniles. The species has a large mouth with an upper jaw that extends back past the eye in adults, and a tongue that lacks teeth. Micropterus salmoides have 3 anal spines, 9-11 dorsal spines, typically 58-73 lateral scales, and 8 rakers on its first gill arch (Page and Burr 2011; Robins et al. 2018). Morphological descriptions are also given in Becker (1983), Etnier and Starnes (1993), Jenkins and Burkhead (1994), and Moyle (2002).

Two subspecies of Largemouth Bass are recognized (Bailey and Hubbs 1949). The Florida Bass (Micropterus s. floridanus) attains a larger size than the Northern Largemouth Bass (Micropterus s. salmoides). Micropterus s. floridanus typically has 31 or more branches on the pyloric caeca (second stomach), 65-77 (typically 69-73) lateral scales, and 27-34 (typically 29-31) scales around the caudal peduncle. The Northern Largemouth Bass (Micropterus s. salmoides) typically has fewer than 28 branches on the pyloric caeca, 58-69 (typically 59-67) lateral scales, and 24-32 (typically 27-28) scales around the caudal peduncle (Robins et al. 2018).

Size: 97 cm (Robins et al. 2018).

Native Range: Largemouth Bass are native to the St. Lawrence and Great Lakes, Hudson Bay (Red River), and Mississippi River basins from southern Quebec to Minnesota and south to the Gulf. Its native range also includes the Atlantic Slope drainages from North Carolina to Florida, and the Gulf Slope drainages from southern Florida into northern Mexico (Page and Burr 2011).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Native range data for this species provided in part by NatureServe

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Largemouth bass occupy a variety of habitats ranging from large lakes, rivers, and reservoirs, to smaller waterbodies such as swamps, ponds, and creek pools. (Claussen 2015; Page and bur 2011; Robins et al. 2018). Although they thrive in most aquatic environments, M. salmoides tend to be most abundant in warm eutrophic lakes, rivers, and reservoirs that are highly vegetated. Bass are often associated with shallow shorelines, and they are commonly concentrated in areas with submerged structure such as logs, rocks, and aquatic macrophyte beds (Claussen 2015).

Largemouth Bass are opportunistic feeders that exploit a wide variety of prey. They feed predominately by sight, but also utilize their sense of smell and lateral line to capture prey (Janssen and Corcoran 1993). Because M. salmoides feed largely by sight, they prefer clear rather than turbid waters (Killgore et al. 1989; Sowa and Rabeni 1995). Largemouth Bass are voracious feeders and will consume almost any prey they can fit in their mouth and swallow whole. As adults, Largemouth bass are highly piscivorous, and they are often the dominant carnivores in the systems they inhabit (Howick and O’Brien 1983; Claussen 2015).

Means of Introduction: Intentional stocking for sportfishing. This species is an important sportfish, and it has been stocked extensively outside of its native range for purpose of angling (Maceina and Murphy 1992; Claussen 2015).

Status: Established in most locations.

Impact of Introduction: The introduction of Largemouth Bass usually impact populations of small native fishes directly through predation, sometimes resulting in the decline or extinction of such species (Minckley 1973). Species that have suffered such effects include relict dace (Relictus solitarius), Clover Valley speckled dace (Rhinichthys osculus oligoporus), Independence Valley tui chub (Gila bicolor lethoporus) (U.S. Fish and Wildlife Service 1985), a distinct population of Gila chub (G. intermedia), Monkey Spring pupfish (Cyprinodon sp.) (Minckley 1973), White River springfish (Crenichthys baileyi), Pahranagat roundtail chub (Gila robusta jordani) (U.S. Fish and Wildlife Service 1985), Owens pupfish (Cyprinodon radiosus) (Miller and Pister 1971), wild brook trout (Salvelinus fontinalis) (Boucher 2003), and White River spinedace (Lepidomeda albivallis) (U.S. Fish and Wildlife Service 1994). Jenkins and Burkhead (1994) speculated that introduced Largemouth Bass may have contributed to the demise of an isolated population of trout-perch (Percopsis omiscomaycus) in the Potomac River in Virginia and Maryland. Introduced predatory centrarchids are likely responsible for the decline of native ranid frogs in California, California tiger salamander (Ambystoma californiense) populations (Hayes and Jennings 1986; Dill and Cordone 1997), and the Chiricahua leopard frog (Rana chiricahuensis) in southeastern Arizona (Rosen et al. 1995). In Squaw Creek Reservoir in northcentral Texas, introduced Florida largemouth intergrade with native northern largemouth (Whitmore and Hellier 1988). Nonnative predators, including Largemouth Bass, have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Hughes and Herlihy 2012). The presence of Largemouth Bass, along with other introduced piscivores, reduced the richness of native minnow communities in Adirondack lakes (Findlay et al. 2000).

Remarks: This account includes introductions of both subspecies M. s. salmoides, the northern Largemouth Bass, and M. s. floridanus, the Florida Largemouth Bass. For instance, both subspecies have been introduced into Nevada (Deacon and Williams 1984). Tyus et al. (1982) gave a distribution map of the this species in the upper Colorado basin. MacCrimmon and Robbins (1975) showed a map depicting this species' native and introduced range. Jenkins and Burkhead (1994) reported the largemouth as introduced into the Roanoke drainage in Virginia. Recently prehistoric bones of M. salmoides were discovered near the Roanoke River in Roanoke, Virginia, indicating that the species is native there (Jenkins, personal communication).

Introduced Florida Largemouth Bass are known to hybridize with native populations of northern Largemouth Bass (Whitmore and Hellier 1988), with introgression of Florida bass genes into populations occurring rapidly (Gelwick et al. 1995) and dispersing away from original introduction/stocking sites (Ray et al. 2012).

References: (click for full references)

Bailey, R.M., and C.L. Hubbs. 1949. The black basses (Micropterus) of Florida, with description of a new species. Occassional Papers of the Museum of Zoology, University of Michigan 516:1-40.

Becker, G.C. 1983. Fishes of Wisconsin. University of Madison Press, Madison, WI.

Boucher, D. 2003. Illegal fish stockings threaten Maine lakes and rivers. Available online at URL http://www.state.me.us

Claussen, J.E. 2015. Largemouth Bass Micropterus salmoides (Lacepède, 1802). Pages 27-34 in Tringali, M.D., J.M. Long, T.W. Birdsong, and M.S. Allen (eds.), eds. Black bass diversity: multidisciplinary science for conservation. Volume 82. American Fisheries Society. Bethesda, MD.

Deacon, J.E. and J.E. Williams. 1984. Annotated list of the fishes of Nevada. Proceedings of the Biological Society of Washington 97(1):103-118.

Dill, W.A., and A.J. Cordone. 1997. History and status of introduced fishes in California, 1871-1996. California Department of Fish and Game Fish Bulletin, volume 178.

Etnier, D.A., and W.C. Starnes. 1993. The fishes of Tennessee. University of Tennessee Press, Knoxville, TN.

Findlay, C.S., D.G. Bert, and L. Zheng. 2000. Effect of introduced piscivores on native minnow communities in Adirondack lakes. Canadian Journal of Fisheries and Aquatic Sciences 57:570-580. http://www.nrcresearchpress.com/doi/pdf/10.1139/f99-276

Gelwick, F.P., E.R. Gilliland, and W.J. Matthews. 1995. Introgression of the Florida largemouth bass genome into stream populations of northern largemouth bass in Oklahoma. Transactions of the American Fisheries Society 124(4):550-560.

Hayes, M.P., and M.R. Jennings. 1986. Decline of ranid frog species in western North America: are bullfrogs (Rana catesbeiana) responsible? Journal of Herpetology 20(4):490-509.

Howick, G.L., and W.J. O'Brien. 1983. Piscivorous feeding behavior of largemouth bass: an experimental analysis. Transactions of the American Fisheries Society 11(2):508-516. https://doi.org/10.1577/1548-8659(1983)112<508:PFBOLB>2.0.CO;2

Hughes, R.M. and A.T. Herlihy. 2012. Patterns in catch per unit effort of native prey fish and alien piscivorous fish in 7 Pacific Northwest USA rivers. Fisheries 37(5):201-211.

Janssen, J., and J. Corcoran. 1993. Lateral line stimuli can override vision to determine sunfish strike trajectory. Journal of Experimental Biology 176(1):299-305. https://jeb.biologists.org/content/176/1/299.short

Jenkins, R.E., and N.M. Burkhead. 1994. Freshwater Fishes of Virginia. American Fisheries Society, Bethesda, MD.

Killgore, K.J., R.P. Morgan II, and N.B. Rybicki. 1989. Distribution and abundance of fishes associated with submersed aquatic plants in the Potomac River. North American Journal of Fisheries Management 9:101-111.

MacCrimmon, H.R., and W.H. Robbins. 1975. Distribution of black basses in North America. 56-66 in R.H. Stroud, and H. Clepper, eds. Black bass biology and management. Sport Fishing Institute, Washington, D.C.

Maceina, M.J., and B.R. Murphy. 1992. Stocking Florida largemouth bass outside its native range. Transactions of the American Fisheries Society 121:686-688.

Miller, R.R., and E.P. Pister. 1971. Management of the Owens pupfish, Cyprinodon radiosus, in Mono County, California. Transactions of the American Fisheries Society 100(3):502-509.

Minckley, W. L. 1973. Fishes of Arizona. Arizona Fish and Game Department. Sims Printing Company, Inc., Phoenix, AZ.

Moyle, P.B. 2002. Inland fishes of California. 2nd edition. University of California Press, Berkeley, CA.

Page, L.M., and B.M. Burr. 2011. Field guide to freshwater fishes of North America north of Mexico. Peterson Field Guides series. Houghton Mifflin Harcourt, Boston, MA.

Ray, J.W., M. Husemann, R.S. King, and P.D. Danely. 2012. Genetic analyses reveal dispersal of Florida bass haplotypes from reservoirs to rivers in central Texas. Transactions of the American Fisheries Society 141(5):1269-1273.

Robins, R.H., L.M. Page, J.D. Williams, Z.S. Randall, and G.E. Sheehy. 2018. Fishes in the fresh waters of Florida: an identification guide and atlas. University of Florida Press, Gainesville, FL.

Rosen, P.C., C.R. Schwalbe, D.A. Parizek, Jr., P.A. Holm, and C.H. Lowe. 1995. Introduced aquatic vertebrates in the Chiricahua region: effects on declining native ranid frogs. 251-261 in Biodiversity and management of the Madrean Archipelago: the sky island of the southwestern United States and northwestern Mexico. USDA Forest Service General Technical Report RM-GTR-264.

Sowa, S.P., and C.F. Rabeni. 1995. Regional evaluation of the relation of habitat to distribution and abundance of smallmouth bass and largemouth bass in Missouri streams. Transactions of the American Fisheries Society 12(2):240-251. https://doi.org/10.1577/1548-8659(1995)124<0240:REOTRO>2.3.CO;2

Tyus, H.M., B.D. Burdick, R.A. Valdez, C.M. Haynes, T.A. Lytle, and C.R. Berry. 1982. Fishes of the upper Colorado River basin: distribution, abundance, and status. 12-70 in W.H. 

U.S. Fish and Wildlife Service. 1985. Recovery plan for the Pahranagat roundtail chub, Gila robusta jordani. U.S. Fish and Wildlife Service, Portland, Oregon.

U.S. Fish and Wildlife Service. 1994. White River spinedace, Lepidomeda albivallis, recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon.

Whitmore, D.H. and T.R. Hellier. 1988. Natural hybridization between largemouth and smallmouth bass (Micropterus). Copeia 1988(2):493-396.

Other Resources:
Distribution in Illinois - ILNHS

Micropterus salmoides (Global Invasive Species Database)

US Fish and Wildlife Service Ecological Risk Screening Summary for Micropterus salmoides

Author: Fuller, P., Neilson, M., and Procopio, J.

Peer Review Date: 7/23/2015

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.