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.

Aplodinotus grunniens
Aplodinotus grunniens
(Freshwater Drum)
Native Transplant

Copyright Info
Aplodinotus grunniens Rafinesque, 1819

Common name: Freshwater Drum

Synonyms and Other Names: bubbler, croaker, gaspergou, gou, gray bass, grinder, grunt, lake drum, sheepshead, silver bass, thunder pumper 

Taxonomy: available through www.itis.govITIS logo

Identification: Laterally compressed, silver, deep bodied fish. Has a long dorsal fin relative to its total length containing a deep notch. Mouth is sub-terminal with a blunt rounded snout (Goldstein and Simon 1999). Anal fin has seven soft rays and two spines, with the first being much shorter than the second. Dorsal fin usually has 10 spines and 29 to 32 rays. Possesses 20-24 gill rakers (Knapp 1953). A unique feature of these fish is that the lateral line extends into their rounded caudal fin. Scales are ctenoid and the number of scales on the lateral line ranges from 49 to 53 (Hubbs et al. 1991). Except for general coloration and the absence of a dark spot on the caudal fin, this species closely resembles its saltwater relative, the red drum (Etnier and Starnes 1993, MN DNR 2005, Robison and Buchanan 1988, Ross and Brenneman 2001, TPWD 2009, Trautman 1981).

95 cm maximum length (IGFA 2001), 45 cm common length (Frimodt 1995). Sexual maturity is reached at 20 cm length (Diaber 1953, Priegel 1969, Wrenn 1969).

Size: 95 cm maximum length

Native Range: East of the Rocky Mountains in the St. Lawrence-Great Lakes, Hudson Bay, and Mississippi River basins from Quebec to northern Manitoba and southern Saskatchewan in Canada and south to the Gulf of Mexico. Present in the Rio Grande and other Texas rivers, and Gulf Coast drainages from Mobile Bay, Georgia and Alabama, through eastern Mexico to the Rio Usumacinta system in Guatemala (Barney 1926, Page and Burr 1991). This species is native and abundant in Lakes Michigan, Huron, Erie, and Ontario (Bean 1903, Cudmore-Vokey and Crossman 2000, Dekay 1855, Forbes and Richardson 1908, Halkett 1913, Richardson 1831).

Native range data for this species provided in part by NatureServe NS logo
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Aplodinotus grunniens are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CO195120095Republican; South Fork Republican; South Platte; Upper Arkansas; Upper Arkansas-John Martin Reservoir
MN200120063Lake Superior; Lower Rainy; St. Louis
NM200920091Elephant Butte Reservoir
NY199620084Hudson-Hoosic; Lower Hudson; Middle Hudson; Mohawk
NC200620131Middle Roanoke
PA198320202Schuylkill; Youghiogheny
TX201220121San Fernando
WI194719471Upper Wisconsin
WY199419942Lower Laramie; Upper Belle Fourche

Table last updated 8/1/2021

† Populations may not be currently present.

Ecology: Aplodinotus grunniens is the only member of its family in North America to occur completely in freshwater habitats. It typically inhabits the bottom of medium to large rivers and lakes up to about 40 to 60 foot depths (Etnier and Starnes 1993, Scott and Crosman 1973). It is tolerant of both clear and turbid conditions (Fremling 1980). Individuals have been observed to become stressed when water temperature exceed 25.6°C and when dissolved oxygen concentrations remain low over an extended period (Priegel 1976). The adult diet consists mainly of immature insects, crayfish, minnows, amphipods, and mollusks, while young fish feed on zooplankton (Daiber 1952, Etnier and Starnes 1993, Fremling 1980). The Freshwater Drum often roots around in the substrate or move rocks on the bottom to dislodge its prey and will feed throughout all hours of the night (Priegel 1967). Spawning occurs in open water during May and June when water temperatures reach 18-26°C (Fremling 1980, Swedberg and Walburg 1970, Wrenn 1969). Large females are capable of laying up to 600,000 positively buoyant eggs (Fremling 1980, Wrenn 1969), which float at the surface until they hatch roughly 24 hours later in warmer waters (Swedberg and Walburg 1970). Sexual maturity is reached after 4 to 6 years, with individuals measuring at least about 200 mm in length (Diaber 1953, Priegel 1969, Wrenn 1969). The maximum reported age of this species is 13 years (Altman and Dittmer 1962), but on average, it lives for 6-8 years (Etnier and Starnes 1993, Ross and Brenneman 2001).

Means of Introduction: Freshwater Drum was stocked in the late 1800s in Illinois lakes as a sport fish (Bean 1892), and later in Colorado in the 1950s for the same reason (Everhart and Seaman 1971). It was accidentally stocked in two Wyoming reservoirs in the early 1990s (Hubert 1994). The two fish reported from the upper Wisconsin drainage in Wisconsin were likely the result of fish rescue and transfer operations from the Mississippi River in the 1930s (Becker 1983).

Great Lakes
Prior to the 1970s, discovery of this species in Lake Superior was considered highly likely, as it was already present in all of the other Great Lakes, including Lake Huron to which Lake Superior is directly connected (Barney 1926, Richardson 1831). Dispersal through the canal and lock system from Lake Huron is thought to be the primary pathway of introduction (N. Mandrak, Fisheries and Oceans Canada, pers. comm.).

Status: Established in Lake Superior (Peterson et al. 2011; Roth et al. 2013). Established in Colorado; reported in Illinois, Wisconsin, and Wyoming. Extirpated in Pennsylvania (Hendricks et al. 1983).


Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: In Wisconsin, there are no other records of Freshwater Drum from the upper Wisconsin River; the species is considered native farther downstream near and below the Portage area (Becker 1983).

This species earned part of its Latin name, grunniens, due to the odd grunting noises it is capable of generating. These noises are produced by a set of muscles located in the body cavity that vibrate against the swim bladder. When removed from the water, they produce a frog-like croaking sound.

References: (click for full references)

Altman, P.L., and D.S. Dittmer. 1962. Growth, including reproduction and morphological development. Federation of American Societies for Experimental Biology, Washington, D.C.

Barney, R.L. 1926. The distribution of the fresh-water sheepshead, Aplodinotus grunniens Rafinesque, in respect to the glacial history of North America. Ecology 7(3): 351-364.

Bean, T.H. 1892. Observations upon fish and fish-culture. Bulletin of the U.S. Fish Commission for 1890 10: 49-61.

Bean, Tarleton H. 1903. The food and game fishes of New York; notes on their common names, distribution, habits, and mode of capture. 7th Annual Report. State of New York Forest, Fish and Game Commission, New York, III, 784.

Becker, G.C. 1983. Fishes of Wisconsin. University of Wisconsin Press, Madison, Wisconsin: 1052 pp.

Beckman, W.C. 1952. Guide to the Fishes of Colorado. University of Colorado Museum, Boulder, Colorado: 110 pp.

Cudmore-Vokey, B., and E.J. Crossman. 2000. Checklists of the fish fauna of the Laurentian Great Lakes and their connecting channels. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2550: v+39p.

Daiber, F.C. 1953. Notes on the spawning population of the freshwater drum (Aplodinotus grunniens Rafinesque) in western Lake Erie. American Midland Naturalist. 50: 159-171.

Dekay, James Ellsworth. 1855. Catalogue of the fishes inhabiting the State of New York, as classified and described in part IV of the New York fauna, with an appendix containing a list of the fishes inhabiting the State, discovered since the publication of the zoology.

Ellis, M. M. 1974. Fishes of Colorado. University of Colorado Studies, Boulder, CO 11(1):1-136.

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

Everhart, W. H., and W. R. Seaman. 1971. Fishes of Colorado. Colorado Game, Fish and Parks Division, Denver, CO. 75 pp.

Forbes, Stephen A., and R.E. Richardson. 1908. The fishes of Illinois. Natural History Survey, Illinois State Laboratory of Natural History, III, 358 pp.

Fremling, C.R. 1980. Aplodinotus grunniens (Rafinesque), Freshwater drum. pp. 756 in D.S. Lee, et al. Atlas of North American Freshwater Fishes. North Carolina State Museum Natural History, Raliegh, i-r: 854 pp.

Frimodt, C. 1995. Multilingual illustrated guide to the world's commercial coldwater fish. Fishing News Books, Osney Mead, Oxford, England. 215 pp.

Halkett, A. 1913. Checklist of fishes of the Dominion of Canada and Newfoundland. Ottawa: 138 pp.

Hendricks, M.L., J.R. Stauffer, Jr., and C.H. Hocutt. 1983. The zoogeography of the fishes of the Youghiogheny River system, Pennsylvania, Maryland and West Virginia. American Midland Naturalist 110(1): 145-164.

Hubbs, C., R.J. Edwards, and G.P. Garrett. 1991.  An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. The Texas Journal of Science, Supplement  43(4): 1-56.

Hubert, W. 1994. Exotic fish. Pages 158-174 in T. L. Parrish, and S. H. Anderson, editors. Exotic species manual. Wyoming Game and Fish Department, Laramie, WY.

International Game Fish Association (IGFA). 2001. Database of IGFA angling records until 2001. IGFA, Fort Lauderdale, United States.
Knapp, F.T. 1953. Fishes found in the freshwater of Texas. Ragland Studio and Litho Printing Co., Brunswick, Georgia. 166 pp.

Meyers, T.R., S. Short, K. Lipson, W.N. Batts, J.R. Winron, J. Wilcock, and E. Brown. 1994. Association of viral hemorrhagic septicemia virus with epizootic hemorrhages of the skin in Pacific herring (Clupea harengus pallasi) from Prince William Sound and Kodiak Island, Alaska, USA. Diseases of Aquatic Organisms 19: 27-37.

Mills, E.L., D.L. Strayer, M.D. Scheuerell, and J.T. Carlton. 1996. Exotic Species in the Hudson River Basin: A history of invasions and introductions. Estuaries 19(4): 814-823.

Minnesota Department of Natural Resources (MN DNR). 2005. "Freshwater Drum (Sheepshead)" (http://www.dnr.state.mn.us/fish/freshwaterdrum.html). Accessed May 24, 2011.

Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin Company, Boston, MA.

Priegel, G.R. 1967. The freshwater drum – its life history, ecology and management. Wisconsin Department of Natural Resources Publication 236. 15 pp.

Richardson, Sir John. 1831. Fauna Boreali-Americana; or the zoology of northern parts of British America. Part III, The Fishes. London and Norwich. 327 pp.

Robison, H., and T. Buchanan. 1988. Fishes of Arkansas. Fayetteville, Arkansas: University of Arkansas Press.

Ross, S., and W. Brenneman. 2001. The Inland Fishes of Mississippi. Jackson, Mississippi: University Press of Mississippi.

Roth, B.M., N.E. Mandrak, T.R. Hrabik, G.G. Sass, and J. Peters. 2013. Fishes and decapods crustaceans of the Great Lakes basin. in W.W. Taylor, N. Leonard, and A. Lynch (eds.). Great Lakes fisheries policy and management: a binational perspective, Second Edition. Michigan State University Press, East Lansing, MI.

Schmidt, R.E., and T.R. Lake. 2006. The role of tributaries in the biology of Hudson River fishes. In J. Levinton and J.R. Waldman (editors). The Hudson River Estuary. pp 205-216.

Schmidt, R.E., R. Morse, and B. Weatherwax. 2007. First record of central stoneroller (Campostoma anomalum) in the tidal Hudson River. Northeastern Naturalist 14(3): 492-494.

Scott, W.B., and E.J. Crossman. 1973. Freshwater Fishes of Canada. Fisheries Research Board of Canada, Ottawa. Bulletin 184: 966 pp.

Swedberg, D.V., and C.H. Walburg. 1970. Spawning and early life history of the freshwater drum in Lewis and Clark Lake, Missouri River. Transactions of the American Fisheries Society 99(3): 560-570.

Texas Parks and Wildlife Department (TPWD). 2009. “Freshwater Drum (Aplodinotus grunniens)” (http://www.bio.txstate.edu/~tbonner/txfishes/aplodinotus%20grunniens.htm). Accessed May 24, 2011.

Trautman, M.B. 1981. The Fishes of Ohio: with illustrated keys. Columbus, Ohio: Ohio State University Press.

United States Department of Agriculture (USDA). 2006. Viral Hemorrhagic Septicemia in the Great Lakes: July 2006 Emerging Disease Notice. Animal and Plant Health Inspection Service. (http://www.aphis.usda.gov/vs/ceah/cei/taf/emergingdiseasenotice_files/vhsgreatlakes.htm) Revision date: 12/8/2006.

Walker, P. - Colorado Division of Wildlife, Brush, CO.

Wisconsin Sea Grant. 2002. “Freshwater Drum” (http://seagrant.wisc.edu/greatlakesfish/fdrum1.html). Accessed May 24, 2011.

Wren, M., and S. Lee. 2006. DEC Confirms virus in Lake Ontario and St. Lawrence River fish; Cornell University, USGS document cases of Viral Hemorrhagic Septicemia. New York State NEWS, Department of Environmental Conservation, New York. (http://www.dec.state.ny.us/website/press/pressrel/2006/200683.html) Revision date: 6/13/2006.

Wrenn, W.B. 1969. Life history aspects of smallmouth buffalo and freshwater drum in Wheeler Reservoir, Alabama. Proceedings of the Southeastern Association of Game Fish Committee 22: 479-495.


FishBase Summary

Author: Fuller, P., K. Dettloff, and R. Sturtevant

Revision Date: 9/12/2019

Peer Review Date: 2/6/2015

Citation Information:
Fuller, P., K. Dettloff, and R. Sturtevant, 2021, Aplodinotus grunniens Rafinesque, 1819: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=946, Revision Date: 9/12/2019, Peer Review Date: 2/6/2015, Access Date: 8/1/2021

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.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2021]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [8/1/2021].

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