Invasion History

First Non-native North American Tidal Record: 2002
First Non-native West Coast Tidal Record: 2002
First Non-native East/Gulf Coast Tidal Record: 2005

General Invasion History:

Spotted Bass (Micropterus punctulatus) has been stocked less widely (12 states) than the Largemouth Bass (M. salmoides and M. dolomieu), mostly by state agencies (Fuller et al. 1999). It is native to the Mississippi basin from Ohio and West Virginia to Kansas, and south to Gulf of Mexico drainages from Georgia to Texas (Page and Burr 1991). It has been introduced outside its native range in 26 US states and South Africa (USGS Nonindigenous Aquatic Species Program 2018).

North American Invasion History:

Invasion History on the West Coast:

In 1936–37, Spotted Bass from Ohio ('Kentucky Bass') were introduced to San Joaquin River tributaries in 1937, and became established in the lowermost reaches of Delta tributaries. This species was chosen as having intermediate habitat requirements between the Smallmouth Bass (M. dolomieu) and the Largemouth Bass (M. salmoides), and more suitable for foothill streams and reservoirs. However, success was difficult to determine, due to similarity with the other 'black basses' and hybridization with Smallmouth Bass. The only purebred Spotted Bass were believed to occur in the lowermost reaches of the Cosumnes and Mokelumne rivers (Dill and Cordone 1997). In 1974–1977, Alabama Bass (M. henshalli), then considered a subspecies of M. punctulatus, were stocked in foothill streams and reservoirs, in hopes of developing more extensive populations (Dill and Cordone 1997). 'Spotted Bass' were reported from the freshwater Delta in 1980s, but the exact species identity is unclear (Light et al. 2005; Brown and Michniuk 2007; Cavallo et al. 2014). This fish was present in small (0.7%, Cavallo et al. 2014) to very small numbers (<0.1%) (Brown and Michniuk 2007). Spotted Bass have been introduced to lakes and reservoirs in San Diego, Riverside, and Shasta Counties (Dill and Cordone 1997; USGS Nonindigenous Aquatic Species Program 2018).

Invasion History on the East Coast:

On the East Coast, Spotted Bass were stocked in the James River (Appomattox River) and York River systems, in Virginia (South Anna, Pamunkey) in 1976–1979, and now established near the head of tide (Jenkins and Burkhead 1995; Virginia Institute of Marine Science 1998-2005; Virginia Division of Game and Inland Fisheries 2018). In 2005, it was listed in the Virginia Juvenile Striped Bass Survey of tidal waters, where it ranked 75th in relative abundance (Virginia Institute of Marine Science 2005). They have also been introduced to upland rivers from Georgia to North Carolina, from 1962 to 2017 (Rohde et al. 1994; USGS Nonindigenous Aquatic Species Program 2018).

Invasion History Elsewhere in the World:

In 1939,120 Spotted Bass were imported to South Africa in order to provide a broodstock for introduction into rivers unsuitable for Largemouth or Smallmouth Bass, because of drought, flooding, or turbidity. They were planted in rivers in Cape and Natal provinces. Some populations persist, but establishment is spotty (Lever 1996). 


Fishes of the genus Centrarchidae (Sunfishes and Black Basses) have a laterally compressed body. They have a spiny and a soft dorsal fin, which are fused. They have 3–8 anal spines, thoracic pelvic fins, and ctenoid scales. Black Basses (Micropterus spp.) are large (over 360 mm), moderately laterally compressed, with an elongated body and a large mouth, extending under or past the eye. The base of the anal fin is less than half the length of the dorsal fin. The tail fin is shallowly forked. There is a black spot at the rear angle of the gill cover but no flap. There are dark brown lines radiating from the snout and back of the eye to the rear edge of the gill-cover (Page and Burr 1991). 

The Spotted Bass is streamlined, with the dorsal profile of the head smoothly convex. The mouth is smaller than that of the Largemouth Bass, with the upper jaw not extending past the rear half of the eye. There are 60–71 lateral line scales, 9–11 dorsal spines, 11–15 dorsal rays, 3 anal spines, and 9–12 anal rays. The dorsal fin is moderately notched where the spiny and soft sections join.The fish can grow to 610 mm, but rarely exceed 400 mm. The body is light gold-green above, with olive mottling on the back and sides, and yellowish white below. Three dark bars radiate from around the eyes to the posterior edge of the gill cover. A row of black blotches (8–11) runs along the lateral line, often forming a continuous stripe on the caudal peduncle, and ending in a solid dark tail spot. Underneath the blotches, there are several rows of small black spots (Page and Burr 1991; Jenkins and Burkhead 1993; Moyle 2002).

Spotted Bass was formerly regarded as consisting of two subspecies, (M. p. punctulatus, native to the lower Mississippi -Gulf Basin, and M. p. henshalli (Alabama Spotted Bass), native to a more restricted range. In central Alabama, Micropterus henshalli (Alabama Bass) has been raised to full species status (Baker et al. 2008). Both fishes have been introduced to the San Francisco Bay watershed, and other streams in California, as 'Spotted Bass' in field collections, so we will treat them together, noting the morphological differences. 'Spotted Bass' (Micropterus punctulatus s.l. ) are in many characteristics an intermediate between M. salmoides (Largemouth Bass) and M. dolomieu (Smallmouth Bass). They were not recognized as a distinct from the Smallmouth Bass until 1927 (Hubbs 1927; cited by Jenkins and Burkhead 1993).

The Alabama Bass (M. henshalli) is very similar, but with more lateral line scales (68-84), a narrower head, and narrower scales. The blotches (10-13) remain separate on the caudal peduncle (Baker et al. 2008). The specimens examined by Baker et al. ranged up to 433 mm (Baker et al. 2008).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Chordata
Subphylum:   Vertebrata
Superclass:   Osteichthyes
Class:   Actinopterygii
Subclass:   Neopterygii
Infraclass:   Teleostei
Superorder:   Acanthopterygii
Order:   Perciformes
Suborder:   Percoidei
Family:   Centrarchidae
Genus:   Micropterus
Species:   punctulatus


Calliurus punctulatus (Rafinesque, 1817)
Micropterus pseudaplites (Hubbs, 1927)
Micropterus punctulatus (Hubbs and Bailey, 1940)

Potentially Misidentified Species

Micropterus coosae
Redeye Bass Micropterus coosae has a large mouth, with the upper maxilla extending under the rear half of the eye. The fins are brick red, with a white edge to the upper and lower edges of the tail fin. There are rows of small spots on the sides. Redeye Bass are native to the Coosa River basin of Tennessee, Georgia, and Alabama (Page and Burr 1991). They are introduced to the San Francisco estuary watershed and other basins in California (Dill and Cordone 1997; Moyle 2002).

Micropterus dolomieu
Smallmouth Bass (Micropterus dolomieu) has clear fins, 8-16 dark bars on the side, and lacks rows of spots. It is native to the Great Lakes, upper Mississippi Basin, and is introduced to San Francisco and Columbia River estuaries, and Northeastern estuaries from Maine to Virginia. Smallmouth Bass are found in cool lakes and flowing waters (Page and Burr 1991).

Micropterus henshallae
Alabama Bass (Micropterus henshalli) was formerly regarded as a subspecies of Spotted Bass (M. punctulatus). It is native to central Alabama It was stocked in Millerton Lake in the San Joaquin River in 1974. Both Spotted and Alabama Bass are established in the Sacramento-San Joaquin watershed (Dill and Cordone 1997).

Micropterus salmoides
Largemouth Bass (Micropterus salmoides) has a large mouth, with the upper jaw extending past the eye. The front and rear dorsal are nearly separate. There is a broad, black band extending from the eye to the tail, sometimes broken up into blotches. Largemouth Bass are characteristic of lakes and large rivers, with clear water and dense vegetation. Largemouth Bass are native to the Great-Lakes-Mississippi basin, and the Atlantic Slope from North Carolina to Florida. It is introduced to the Columbia River and San Francisco estuaries, and from Chesapeake Bay to Maine (Page and Burr 1991).



Spotted Bass (Micropterus punctulatus) is a predatory freshwater fish. Spotted Bass mature at year 2 or 3 at 152–323 mm (Jenkins and Burkhead 1993; Moyle 2002). Spawning takes place at 15–19 C. In streams, males excavate and guard nests in shallow water at the edge of pools, or in deeper water on firm or soft bottoms in reservoirs. Females described from an Arkansas reservoir may carry 2800 to 36,000 eggs; nests contained 87 to 3800 larvae. The eggs are guarded by the male, but the larvae are more active, and leave at an earlier age than those of Smallmouth Bass (Jenkins and Burkhead 1993; Moyle 2002).

Spotted Bass (Micropterus punctulatus) are native to the central and southern Mississippi-Gulf region can probably tolerate moderately long cold-winters and hot summers. In experiments, they tolerated temperatures up to 38 °C. Spotted Bass are mostly an inland freshwater fish, but they have been collected at 10 PSU in Biloxi Bay (Peterson 1988). In Chesapeake Bay, they occur primarily just below the Fall Line, at the head of tide, in the James and Pamunkey Rivers (Jenkins and Burkhead 1994; Virginia Division of Inland Fisheries 2018). In the San Francisco estuary, Spotted Bass have been collected in small numbers in the freshwater tidal edges of the Delta (Brown and Michniuk 2007; Cavallo et al. 2014). Spotted Bass are usually considered to be intermediate between Smallmouth Bass and Largemouth Bass in habitat preference in warm, clear to moderately turbid, moderate gradient-streams and rivers, but usually avoiding backwaters with heavy growths of aquatic plants. In reservoirs, adults tend to move into deeper waters. Juvenile Spotted Bass feed on micro-crustaceans and small insects, and as they grow, shift to crayfish, larger insects, and fishes (Jenkins and Burkhead 1993; Moyle 2002). As with the other 'black basses', humans are the chief predators on adults.

Micropterus henshalli (Alabama Bass) was formerly regarded as a subspecies of Micropterus punctulatus and differs somewhat in its habitat preferences, life history, and growth characteristics. Alabama Bass were introduced to California reservoirs, because they were believed to grow faster and live longer in some Alabama reservoirs, and were more tolerant of rapid changes in water levels, and barren or rocky habitat, compared to northern Spotted Bass (Dill and Cordone 1997). The abundance, range, and habitat of M. henshalli, and the occurrence of hybridization in California are unknown.


insects; crayfish; fishes


fish, birds, mammals, humans


Micropterus spp.

Trophic Status:




General HabitatNontidal FreshwaterNone
General HabitatRockyNone
General HabitatGrass BedNone
General HabitatCoarse Woody DebrisNone
General HabitatTidal Fresh MarshNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Salinity RangeMesohaline5-18 PSU
Tidal RangeSubtidalNone
Vertical HabitatNektonicNone

Life History

Tolerances and Life History Parameters

Maximum Temperature (ºC)37.8This was the upper end of range in a preferred temperature experiment (Carlander 1977).
Minimum Salinity (‰)0This is a freshwater species.
Maximum Salinity (‰)10Field record, Biloxi Bay Missippi (Peterson 1988).
Minimum Reproductive Temperature15Jenkins and Burkhead 1993
Minimum Length (mm)216Minimum adult size (Jenkins and Burkhead 1993)
Maximum Length (mm)610Page and Burr 1991, but rarely over 400 mm ( Moyle 2002)

General Impacts

Spotted and Alabama Bass (Micropterus punctulatus; (M. henshalli ) have been introduced to the San Francisco estuary watershed, as gamefishes. Both species fight well on light tackle, and have supported small, but localized sport fisheries (Dill and Cordone 1997; Moyle 2002). Similarly, in Virginia waters, Spotted Bass fisheries appear to be localized, especially when compared to Largemouth Bass, in the fresh, tidal regions in estuaries (Jenkins and Burkhead 1993; Virginia Division of Game and Inland Fisheries 2018). Ecological impacts of Spotted Bass appear to be small, when compared to those of Largemouth and Smallmouth Bass. This was also true for introductions to South Africa, where establishment was limited by low pH in many rivers (Lever 1996).

Regional Impacts

P090San Francisco BayEcological ImpactPredation
Removal of predators, dominated by Redeye Bass (Micropterus coosae) and Spotted Bass (M. punctulatus), by electrofishing, enhances the survival of tagged Chinook Salmon (Oncorhynchus tshawytscha) in migration through the North Fork of the North Fork Mokelumne River (Cavallo et al. 2013).
CACaliforniaEcological ImpactPredation
Removal of predators, dominated by Redeye Bass (Micropterus coosae) and Spotted Bass (M. punctulatus), by electrofishing, enhances the survival of tagged Chinook Salmon (Oncorhynchus tshawytscha) in migration through the North Fork of the North Fork Mokelumne River (Cavallo et al. 2013).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
M130 Chesapeake Bay 2005 Def Estab
P090 San Francisco Bay 2002 Def Estab
G100 Apalachicola Bay 0 Native Estab
G260 Galveston Bay 0 Native Estab
G250 Sabine Lake 0 Native Estab
G110 St. Andrew Bay 0 Native Estab
G240 Calcasieu Lake 0 Native Estab
G130 Pensacola Bay 0 Native Estab
G230 Mermentau River 0 Native Estab
G120 Choctawhatchee Bay 0 Native Estab
G230 Mermentau River 0 Native Estab
G140 Perdido Bay 0 Native Estab
G220 Atchafalaya/Vermilion Bays 0 Native Estab
G150 Mobile Bay 0 Native Estab
G210 Terrebonne/Timbalier Bays 0 Native Estab
G160 East Mississippi Sound 0 Native Estab
G200 Barataria Bay 0 Native Estab
G190 Mississippi River 0 Native Estab
G170 West Mississippi Sound 0 Native Estab
G170 West Mississippi Sound 0 Native Estab
G180 Breton/Chandeleur Sound 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Baker, Winston; Blanton, Rebecca E,; Johnstov, Carol E. (2013) Diversity within the Redeye Bass, Micropterus coosae (Perciformes: Centrarchidae) species group, with descriptions of four new species, Zootaxa 3635(4): 379-401

Bangs, Max R.; Oswald, Kenneth J.; Greig, Thomas W.; Leitner, Jean K.; Rankin, Daniel M.; Quattro, Joseph M. (2018) Introgressive hybridization and species turnover in reservoirs: a case study involving endemic and invasive basses (Centrarchidae: Micropterus) in southeastern North America, Conservation Genetics 19: 57-69
DOI 10.1007/s10592-017-1018-7

Brown, Larry R.; Michniuk, Dennis (2007) Littoral fish assemblages of the alien-dominated Sacramento-San Joaquin Delta, California, 1980-1983 and 2001-2003., Estuaries and Coasts 90: 186-200

Carlander, Kenneth D. (1977) Handbook of Freshwater Fishery Biology. , In: (Eds.) Handbook of Freshwater Fishery Biology, Volume Two: Life History Data on Centrarchid Fishes of the U.S & Canada. , Ames. Pp. Ames

Cavallo, Bradley; Merz, Joseph; Setka, Jose (2013) Effects of predator and flow manipulation on Chinook salmon (Oncorhynchus tshawytscha) survival in an imperiled estuary, Environmental Biology of Fishes 393: 393-403

Dill, William A.; Cordone, Almo J. (1997) History and status of introduced fishes in California, 1871-1996, California Department of Fish and Game Fish Bulletin 178: 1-414

Jenkins, Robert E.; Burkhead, Noel M. (1993) Freshwater Fishes of Virginia, American Fisheries Society, Bethesda, MD. Pp. <missing location>

Kim, Daemin; Taylor, Andrew T.; Near, Thomas J. (2022) Phylogenomics and species delimitation of the economically important Black Basses (Micropterus), Scientific Reports 12(9113): Published online

Lever, Christopher (1996) Naturalized fishes of the world, Academic Press, London, England. Pp. <missing location>

Light, Theo; Grosholtz, Ted; Moyle, Peter (2005) Delta ecological survey (phase1): Nonindigenous aquatic species in the Sacramento-San Joaquin Delta, a literature review, In: None(Eds.) None. , Stockton, CA. Pp. <missing location>

Moyle, Peter B. (2002) Inland Fishes of California, revised and expanded, University of California Press, Berkeley CA. Pp. <missing location>

Page, Lawrence M.; Burr, Brooks M. (1991) Freshwater Fishes: North America North of Mexico, Houghton-Mifflin, Boston. Pp. <missing location>

Peterson, Mark S. (1988) Comparative physiological ecology of centrarchids in hyposaline environments, Canadian Journal of Fisheries and Aquatic Sciences 45: 827-833

Rohde, Fred C.; Arndt, Rudolf G.; Lindquist, David G.; Parnell, James F. (1994) Freshwater fishes of the Carolinas, Virginia, and Delaware, Universilty of North Carolina Press, Chapel Hill NC. Pp. <missing location>

Salmon, Terry and 21 authors 2014-2022 California Fish Website.

USGS Nonindigenous Aquatic Species Program 2003-2024 Nonindigenous Aquatic Species Database.

Virginia Institute of Marine Science 1998-2005 VIMS's juvenile striped bass seine survey- species caught. <missing URL>