Description
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Animalia | Chordata | Osteichthyes | Perciformes | Centrarchidae | Lepomis |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1900 | Established | Stable | Introduced | Regular Resident | North America | North America | Fisheries(Fisheries Intentional) |
History of Spread
Lepomis macrochirus (Bluegill) is native to the Great Lakes-St. Lawrence and Missisippi Basins from Quebec and NY south to the Gulf; and south on the Coastal Plain and Gulf Slope from Pee Dee or Cape Fear River basins to Rio Grande (Jenkins and Burkhead 1993; Lee et al. 1980; Page and Burr 1991).The original range of L. macrochirus (Bluegill) on the southern Atlantic Coastal Plain is uncertain because of probable early introductions. Lepomis macrochirus was widely introduced by United States Fish Commission and state fish commissions, usually recorded as 'Sun-fish' or 'Bream', probably with a mixture of species. Many of these stockings were of small ponds, recorded by pond name only, so the full extent of the introductions is difficult to trace. Shipments and stocking by United States Fish Commission (USFC) continued into the 1930's and by many state agencies to the present. Lepomis macrochirus have been introduced into river systems in 38 states (Fuller et al. 1999), including HI, and into southern Canada, Panama, Venezuela South Africa, Japan, and the Phillipines (Lever 1996). They occur in the Hudson River (not listed by Mills et al. 1997, but considered 'probably introduced' by Smith and Lake (1990), the San Francisco Bay Delta (Cohen and Carlton 1995), and the Columbia River estuary (Fuller et al. 1999).
Invasions of river basins by L. macrochirus has apparently been facilitated by dams and impoundments. In the Savannah River Basin SC, it is abundant in impoundments, but colonization was unsuccessful in the free-flowing river (Meffe 1991). This fish is also tolerant of disturbances associated with urbanization, and was the only species increasing in abundance from 1958 to 1988 in Tuckahoe Creek VA, in the suburbs of Richmond (Weaver and Garman 1994). Low pH has limited its abundance and colonization of swampy regions of the VA (Jenkins and Burkhead 1993) and the NJ Coastal Plain (Graham and Hastings 1984).
Chesapeake Bay records are summarized below:
James River - Introductions of 390 adult 'Sun-fish' were made by the USFC in 1901 (Ravenel 1902), but the first verified record of L. macrochirus occurred in 1945. It was collected in Dismal Swamp 1941 (Jenkins and Burkhead 1993). Lepomis macrochirus was the only species increasing in abundance between 1958 and 1988 in Tuckahoe Creek, which drains suburban areas around Richmond (Weaver and Garman 1994).
York River - The first verified record of L. macrochirus was in 1938 (Jenkins and Burkhead 1993), and it was abundant in the tidal Pamunkey by 1949 (Raney and Massmann 1953).
Rappahannock River - The first verified record of L. macrochirus was in 1938 (Jenkins and Burkhead 1993). It was rare in estuary in 1951 (Massman et al. 1952), but abundant throughout the river; including the estuary by 1983 (Maurakis et al. 1987).
Potomac River - The first report of this species (as L. pallidus) was in 1900. By 1911: 'This species is taken in the Potomac River; in the Tidal Basin; and in the lower portion of the Eastern Branch' (Bean and Weed 1911). The first verified voucher specimen was collected in 1916. L. macrochirus was probably introduced by United States Fish Commission with mixed batches of 'Bream' or 'Sun-Fishes' (Jenkins and Burkhead 1993). It is now common in tidal fresh water and brackish water (at least to the Wicomico River), but generally less abundant in estuary than L. gibbosus (Pumpkinseed) (Carmichael 1992; Killgore et al. 1989; Lippson et al. 1979; Serafy et al. 1994). It has been recorded at all tidal and nontidal sampling sites at Fort Belvoir VA (Ernst et al. 1995).
Patuxent River - In the late 1940s, L. macrochirus occurred 'mostly in impoundments where it has been stocked', and was not recorded from the estuary (Mansueti 1950), but it is common there now at Jug Bay (Jug Bay Wetlands Sanctuary 1995).
Susquehanna River - 'Two cans of fish from Ohio' were stocked in 1878 in the reservoir at Hollidaysburg PA, Juniata River (Susquehanna drainage) (Creveling 1881). However, L. macrochirus was included in lists of Susquehanna fishes in PA made in 1893 (Bean 1893), 1919 (Fowler 1919), or 1948 (Fowler 1948). 'Bream' were released in the Susquehanna drainage by the United States Fish Commission between 1910-1919 (Bowers 1911; Leach 1921). L. macrochirus was present in the upper Susquehanna drainage (NY) by 1936 and abundant in lower Susquehanna (PA) by 1961 (Bielo 1963).
Upper Bay - Lepomis macrochirus was not reported in early upper Bay surveys (Fowler 1917; Fowler 1933; Hildebrand and Schroeder 1928; Radcliffe and Welsh 1917). However, Fowler apparently overlooked at least one specimen in 1933 ('Swan Creek, near Rock Hall', Kent Co., (Academy of Natural Sciences of Philadelphia). 'Bream' were introduced to upper Bay tributaries by the USFC (e.g. ponds in Bel Air MD; 1909- Bowers 1911; Patapsco River 1919- Leach 1921) and probably also by the Maryland Department of Natural Resources. The first published catch records for the Upper Bay (1958) are a creel survey in Northeast River (Elser 1960). Lepomis macrochirus was rare to common in brackish tributaries (Curtis Creek to Rhode River), but less abundant than L. gibbosus (Carmichael et al. 1992; Hines et al. unpublished data). It was found at Calvert Cliffs and Cove Point in 1971-72 after very heavy rains (including tropical storm 'Agnes') (Academy of Natural Sciences of Philadelphia 1973), but did not occur in later fish surveys there (Horwitz 1987).
Eastern Shore Tributaries- Lepomis macrochirus was collected at several Eastern Shore MD locations (Dorchester County, Caroline County, Queen Annes County, Kent County) by 1949 but probably was introduced much earlier (U.S. National Musem of Natural History 1996). In MD Department of Natural Resources Surveys, L. macrochirus was widespread in Eastern Shore drainages, including the Elk, Choptank, Nanticoke, and Pocomoke (Boward et al. 1998b; Boward et al. 1998d; Kazyak et al. 1998b; Kazyak et al. 1998c
Delaware River - L. macrochirus was recorded from the Delaware River estuary in 1873 (as Icthhelis incisor ), 'quite new to our fauna' (Abbott 1877). The source of this introduction is not known. Extensive stocking has occurred since 1920, but there has been only limited colonization of acidic drainages of the Pine Barrens (Graham and Hastings 1984).
History References - Abbott 1877; Academy of Natural Sciences of Philadelphia 1973; Academy of Natural Sciences of Philadelphia 1996; Bean 1893; Bean and Weed 1911; Bielo 1963; Boward et al. 1998b; Boward et al. 1998d; Bowers 1911; Carmichael et al. 1992; Creveling 1881; Elser 1960; Ernst et al. 1995 ; Fowler 1917; Fowler 1919; Fowler 1933; Fowler 1948; Fuller et al. 1999; Graham and Hastings 1984; Hardy 1978; Hildebrand and Schroeder 1928; Hines et al. unpublished data; Horwitz 1987; Jenkins and Burkhead 1993; Jug Bay Wetlands Sanctuary 1995; Killgore et al. 1989; Leach 1921; Lee et al. 1976; Lippson et al. 1979; Mansueti 1950; Massman et al. 1952; Maurakis et al. 1987; Meffe 1991; Musick 1972a; Page and Burr 1991; Radcliffe and Welsh 1917; Raney and Massman 1953; Serafy et al. 1994; U.S. National Musem of Natural History 1996; Weaver and Garman 1994
Invasion Comments
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 5.0 | 35.0 | 27.0 | 35.0 |
| Salinity (‰) | 0.0 | 18.0 | 0.0 | 7.0 |
| Oxygen | hypoxic | |||
| pH | 4.0000000000 | 10.4000000000 | ||
| Salinity Range | fresh-meso |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 58.0 | 89.0 |
| Typical Adult Size (mm) | 140.0 | 140.0 |
| Maximum Adult Size (mm) | 384.0 | 384.0 |
| Maximum Longevity (yrs) | 11.0 | 11.0 |
| Typical Longevity (yrs | 5.0 | 5.0 |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Lepomis macrochirus (Bluegill) is a widespread sport fish in Chesapeake Bay's freshwater and slightly brackish tidal tributaries.
Fisheries - Lepomis macrochirus is a very popular sport fish, although small (a pan-fish) and a favorite catch of children (Elser 1960; Jenkins and Burkhead 1993). They are larger and more desirable as a sports fish than the native L. gibbosus (Pumpkinseed) and L. auritus (Redbreast Sunfish). However, L. macrochirus is apparently less abundant than L. gibbosus in many Chesapeake tributaries (Carmichael et al. 1992; Hines et al. unpublished data; Killgore et al. 1989; Serafy et al. 1993). Negative effects on native centrarchids and other fish with similar food habits [Notemigonus chrysoleucas (Golden Shiner); Perca flavescens (Yellow Perch); Morone americana (White Perch)] are not known, but fisheries benefits probably exceed negative impacts.
References - Carmichael et al. 1992; Elser 1960; Hines et al. unpublished data; Jenkins and Burkhead 1993; Killgore et al. 1989; Serafy et al. 1993
Economic Impacts Outside of Chesapeake Bay
Lepomis macrochirus (Bluegill) is widely introduced throughout the temperate, low altitude United States and around the world (Carlander 1977; Hardy 1978). Severe competition with native fishes is unlikely in the Atlantic drainage. Lepomis gibbosus (Pumpkinseed) and L. auritis (Redbreast Sunfish) and most other similar centrarchids (sunfishes) and perciforms (perchlike fishes) coexist as natives over part of their range, especially in the Great Lakes, MA valley and parts of the south Coastal Plain (Lee et al. 1980; Page and Burr 1991). In CA, negative interactions with a native sport fish, Archoplites interruptus (Sacramento Perch, Centrarchidae), have been reported (Florida Caribbean Science Center 2000). Lepomis macrochirus have been introduced to drainages in 32 states (Fuller et al. 1999) and at least 12 countries (Lever 1996).
References - Carlander 1977; Florida Caribbean Science Center 2000; Fuller et al. 1999; Hardy 1978; Lee et al. 1980; Lever 1996; Page and Burr 1991
Ecological Impacts on Chesapeake Native Species
Effects of Lepomis macrochirus's (Bluegill's) introduction on abundance of native fish and invertebrate populations in Chesapeake Bay are not well studied. However, extensive experimental and field studies of this fish have been conducted in its native range. Possible impacts are discussed below.
Hybridization - Lepomis macrochirus hybridizes with L. gibbosus (Pumpkinseed) and L. auritis (Redbreast Sunfish) in VA (Jenkins and Burkhead 1993). Lepomis macrochirus X L. gibbosus hybrids are common, especially in artificial ponds, but are usually sterile (Hubbs 1955).
Competition - Lepomis macrochirus, L.auritus, L. gibbosus, and Enneacanthus gloriosus (Blue-Spotted Sunfish) overlap to some extent in habitat preference and diet (Carlander 1977; Flemer and Woolcott 1966; Jenkins and Burkhead 1993).
Lepomis gibbosus (Pumpkinseed) appears to use estuaries to a greater extent, and is more frequent in brackish water, than L. macrochirus (Massmann et al. 1952; Raney and Massmann 1953; Smith 1971). L. gibbosus breeds in tidal fresh and brackish water, while L. macrochirus spawns primarily or exclusively in nontidal waters (Lippson and Moran 1974; Smith 1971; Wang and Kernehan 1974). In a comparison of 27 Ontario lake population, L. gibbosus had delayed maturity and reduced egg production in the presence of L. macrochirus, compared to populations in lakes where L. macrochirus was absent (Fox 1994). In an MI lake, resource partitioning was observed with adult L. macrochirus feeding more on zooplankton in open water and L. gibbosus more on gastropods in vegetation. Juvenile habitat and food use were much more similar between the species (Mittelbach 1984) and competitive relationships change in complex ways with growth (Osenberg et al. 1994). When piscivorous fish are present, Lepomis spp. are restricted to vegetated habitats and competition is intensified. L. gibbosus growth rates and invertebrate size in cages decreased in a linear fashion with increasing L. macrochirus abundance (Mittelbach 1988).
Introductions of L. macrochirus and other introduced centrarchids are blamed for the virtual elimination of Archoplites interruptus (Sacramento Perch), a native centrarchid, from its native habitats in CA, through the L. macrochirus' agressive behavior in feeding, nesting, and use of cover (Moyle 1976).
In a VA Piedmont stream, diets of L. macrochirus, L. gibbosus, L. auritis, and Enneacanthus gloriosus overlapped considerably, but E. gloriosus fed more heavily on copepods and ostracods than the other species (Flemer and Woolcott 1966). We calculated overlap coefficients (Pianka 1975), from Flemer and Woolcott's data. [Values of the coefficient range from 0 (no overlap) to 1.0 (complete overlap]. For L. macrochirus versus L. gibbosus, the overlap coefficient was 0.40, indicating moderate levels of overlap. L. macrochirus had lower levels of overlap with L. gibbosus and E. gloriosus, 0.33 and 0.23, respectively. However, the overlap coefficient for two of the coexisting native species, L. gibbosus and L. auritus was 0.52, so the importance of competition in this assemblage is not clear.
In the Schuylkill River PA, diet habits of L. macrochirus overlapped broadly with L. auritis, L. gibbosus and L. cyanellus, particularly when sewage fly larvae (Psychodidae) dominated all the species' diets. When these larvae were absent, L. macrochirus fed more heavily on annelids and crustaceans than the two native species (L. auritus; L. gibbosus), but overlap was still substantial (Kirby 1982). Lepomis auritus is rare in brackish water (Musick 1972a; Schwartz 1965).
Native Dorosoma cepedianum (Gizzard Shad) competed with juvenile L. macrochirus in experimental ponds in AL, apparently by removing large zooplankton which were L. macrochirus' preferred prey (Kirk and Davis 1985). In experimental aquaria, the presence of Bluegills reduced the feeding rates of /i>Notemigonus chrysoleucas (Golden Shiner) from bottom sediments, the water column, smooth surfaces, and simulated vegetation (Pazkowski 1986).
Predation - Juvenile and adult L. macrochirus (Bluegills) are efficient visual predators, which selectively eat larger zooplankton, and also pick epifaunal invertebrates on vegetation and other surfaces (Flemer and Woolcott 1966; Werner and Hall 1977). The importance of planktivory by L. macrochirus in Chesapeake tributaries is not known, since many native fishes, including clupeids (herrings and shads), cyprinids (minnows), and centrarchids (sunfishes) also have zooplanktivorous feeding habits.
However, L. macrochirus is an opportunistic species. In Lake Ponchartrain LA, L. macrochirus feeds on a wide range of estuarine invertebrates including Rangia cuneata (Wedge Clam), Balanus spp. (barnacles), Rhithropanopeus harrisi (Harris' Mud Crab), Callinectes sapidus (Blue Crabs, very small), and Gammarus spp. (amphipods) (Desselles et al. 1978), but this estuarine diet does not seem greatly different from that of L. gibbosus in Chesapeake Bay (Hildebrand and Schroeder 1928).
Juvenile L. macrochirus fed heavily on Morone saxatilis (Striped Bass) larvae in experiments. This species was abundant in larval nursery areas in the tidal Pamunkey River VA (McGovern and Olney 1988). Lepomis macrochirus also fed on newly stocked Alosa sapidissima (American Shad) larvae in the nontidal Susquehanna River PA (Johnson and Dropkin 1992).
Habitat Change - In small lakes and experimental ponds, planktivorous fishes such as L. macrochirus can have dramatic effects throughout the ecosystem. Selective feeding by L. macrochirus can eliminate larger zooplankton size classes, favoring smaller species which are less efficient grazers, and altering the species composition of the algal community as well, favoring species which had previously been suppressed by zooplankton grazing (Lazarro 1987). In experimental tanks, tanks with added fish had higher turbidity and biomasses of algae than controls, but L. macrochirus treatments had lower algal biomasses than tanks with Dorosoma cepedianum (Gizzard Shad), a less selective feeder. However, colonial green algae were more abundant in the L. macrochirus tanks, possibly because of the selective predation on large zooplankton (Lazarro et al. 1992). The native L. gibbosus, while having some morphological and behavioral biases towards feeding on mollusks and epibenthos (Werner and Hall 1977; Wainwright 1995), also feeds on zooplankton, and had similar effects on experimental pond ecosystems to those reported by Lazarro et al. (1992) for L. macrochirus (Hambright 1994), so that partial displacement of L. gibbosus by L. macrochirus might not greatly affect planktonic foodwebs.
References - Carlander 1977; Desselles et al. 1978; Flemer and Woolcott 1966; Fox 1994; Hambright 1994; Hildebrand and Schroeder 1928; Hubbs 1955; Jenkins and Burkhead 1993;Johnson and Dropkin 1992; Kirby 1982; Kirk and Davis 1985; Lazarro 1987; Lazarro et al. 1992; Lippson and Moran 1974; Massmann et al. 1953; McGovern and Olney 1988; Mittelbach 1984; Mittelbach 1988; Musick 1972a; Osenberg et al. 1994; Pazkowski 1986; Pianka 1975; Raney and Massmann 1953; Schwartz 1965; Smith 1971; Wainwright 1995; Wang and Kernehan 1979; Werner and Hall 1977
Ecological Impacts on Other Chesapeake Non-Native Species
Effects of Lepomis macrochirus's (Bluegill's) introduction on abundance of introduced fish and invertebrate populations in Chesapeake Bay are not well studied. Possible impacts, based on studies in its native range, are discussed below.
Hybridization - Lepomis macrochirus hybridizes wiith Lepomis cyanellus (Green Sunfish) and Lepomis gulosus (Warmouth) in VA (Jenkins and Burkhead 1993).
Competition - Some food and habitat overlap with other introduced Lepomis is likely. However, L. gulosus and L. cyanellus have larger mouths and can take larger prey as adults than L macrochirus. L. microlophus and L. megalotis feed more frequently on molluscs (Carlander 1977; Jenkins and Burkhead 1993; McCrady 1990). All these species are less frequent than L. macrochirus in brackish parts of the Bay (Musick 1972a; Jenkins and Burkhead 1993).
In experimental ponds in MI, L. cyanellus displaced L. macrochirus from food-rich littoral vegetation, forcing L. macrochirus to feed on open-water zooplankton. When both species were confined together in the littoral zone, L. cyanellus had higher growth rates and survivorship than L. macrochirus (Werner and Hall 1976; Werner and Hall 1977). In the Schuylkill River PA, diet habits of L. macrochirus overlapped broadly with L. auritis, L. gibbosus, and L. cyanellus, particularly when sewage fly larvae (Psychodidae) dominated all the species' diets. When these larvae were absent, L. macrochirus fed more heavily on caddisfly larvae than L. cyanellus, and less on molluscs, but overlap was still substantial (Kirby 1982).
In an IL pond with high densities of L. macrochirus), L. gulosus did not become stunted but never constituted more than 5% of the population (Carlander 1977). Lepomis gulosus overlapped considerably in diet with L. macrochirus in Tuckahoe Creek VA, but took a much larger proportion of crayfish (Flemer and Woolcott 1966). Contrary to the usual pattern in freshwater lakes, L macrochirus in Lake Ponchartrain seemed to feed more on molluscs than L. microlophus (Desselles et al. 1978).
In MI lakes, juvenile L. macrochirus appear to slow the growth rates of Micropterus salmoides (Largemouth Bass) by competition among juveniles. The growth reduction persists beyond the period of food overlap, because it delays the switch to fish predation in M. salmoides (Olson 1992). Competitive interactions thus can shift to predatory interactions with growth (Osendorf et al. 1994).
In TX reservoirs, corrrelations between numbers of White Crappie (Pomoxis annularis) and L. macrochirus of different size classes indicated competition among juveniles of the two species, but predation on small L. macrochirus by adult P. annularis. Lakes with dense populations of M. salmoides and intermediate-sized L. macrochirus tended to have stunted P. annularis populations (Cichra et al. 1981).
Food/Prey -Lepomis macrochirus is a frequent prey of M. salmoides (Carlander 1977) and other predatory fishes including P. annularis (Cichra et al. 1981).
References - Carlander 1977; Cichra et al. 1981; Desselle et al. 1978; Flemer and Woolcott 1966; Jenkins and Burkhead 1993; Kirby 1982; McCrady 1990; Musick 1972a; Olson 1992; Osenberg et al. 1994
References
Academy of Natural Sciences of Philadelphia (1973) Preoperational estuarine ecological studies for the Calvert Cliffs Nuclear Power Plant, , Philadelphia. Pp.1998 Ichthyological Collection Catalog. gopher://fowler.acnatsci.org:71
Bean, Barton A.; Weed, Alfred C. (1911) Recent additions to the fish fauna of the District of Columbia, Proceedings of the Biological Society of Washington 24: 171-174
Bean, Tarleton H. (1893) The fishes of Pennsylvania, In: (Eds.) . , Harrisburg PA. Pp.
Bielo, Robert J. (1963) A fishery investigation of the Susquehanna River in Pennsylvania, In: (Eds.) . , Newark. Pp.
Boward, Daniel; Christmas, John; Randle, Douglas; Kazyak, Paul (1997) Chester River Basin: Environmental Assessment Stream Conditions, , Annapolis. Pp.
Boward, Daniel; Dail, Helen M.; Kazyak, Paul F. (1997) Elk River Basin: Environmental Assessment of Stream Conditions, , Annapolis. Pp.
Bowers, George (1911) Bureau of Fisheries- Report of the Commissioner of Fisheries for the fiscal year 1909 and special papers., , Washington DC. Pp.
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
Carmichael, John; Richardson, Brian; Roberts, Margaret; Jordan, Stephen J. (1992) Fish sampling in eight Chesapeake Bay tributaries, CRBM-HI-92-2 , Annapolis, MD. Pp.
Cichra, Charles E.; Noble, Richard L.; Farquar, Bobby W. (1981) Relationships of white crappie populations to largemouth bass and bluegill, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 35: 416-423
Cope, Edward Drinker (1879) The Fishes of Pennsylvania, In: (Eds.) Report of the State Commisioners of Fisheries. , Harrisburg. Pp.
Creveling, John P. (1881) Report of the State Commisioners of Fisheries., In: (Eds.) . , Harrisburg, PA. Pp.
Desselles, Wayne J.; Poirrier, Michael A.; Rogers, James S.; Cashner, Robert C. (1978) A discriminant functions analysis of sunfish (Lepomis) food habits and feeding niche segregation in the Lake Ponchartrain, Louisiana estuary, Transactions of the American Fisheries Society 107: 713-719
Elser, Harold J. (1960) Creel results on the Northeast River, Maryland, 1958, Chesapeake Science 1: 41-47
Ernst, Carl H.; Wilgenbusch, James C.,; Morgan, Donald L.; Boucher, Timothy P.; Sommerfield, Mark (1995) Fishes of Fort Belvoir, Virginia, Maryland Naturalist 39: 1-60
1966 Food habits and distribution of the fishes of Tuckahoe Creek, Virginia, with special emphasis on the bluegill, <i>Lepomis macrochirus</i> Rafinesque.
Fowler, Henry W. (1917) Notes on fishes from New Jersey, Pennsylvania, and Maryland, Proceedings of the Academy of Natural Sciences of Philadelphia 69: 108-126
Fowler, Henry W. (1919) A list of the fishes of Pennsylvania, Proceedings of the Biological Society of Washington 32: 49-74
Fowler, Henry W. (1933) Notes on Maryland fishes, The Fish Culturist 13: 8-9
Fowler, Henry W. (1948) A list of the fishes of Pennsylvania., Bulletin of the Board of Fish Commisioners, Commonwealth of Pennsylvania 7: 1-26
Fox, Michael G. (1994) Growth, density, and interspecific influences on pumpkinseed sunfish life histories, Ecology 75: 1157-1171
Fuller, Pam. L.; Nico, Leo; Williams, J. D. (1999) Nonindigenous fishes introduced into inland waters of the United States, , Bethesda MD. Pp.
Graham, John H.; Hastings, Robert W. (1984) Distribution of sunfishes on the New Jersey coastal plain, Environmental Biology of Fishes 10: 137-148
Hambright, K. David, Drenner, Ray W., McComas, Steven, Hairston, Nelson G., Jr. (1991) Gape-limited piscivores, planktivore size refuges, and the trophic cascade hypothesis, Archiv fur Hydrobiologie 1241: 389-404
Hardy, Jerry D., Jr. (1978) Development of fishes of the Mid-Atlantic Bight. Vol. 3. Aphredoderidae through Rachycentridae., In: (Eds.) . , Washington DC. Pp.
Hildebrand, Samuel F.; Schroeder, William C. (1928) Fishes of Chesapeake Bay, Unites States Bureau of Bisheries Bulletin 53: 1-388
Horwitz, Richard J. (1987) Fish., In: Heck, Kenneth L., Jr.(Eds.) Ecological Studies in the Middle Reach of Chesapeake Bay.. , Berlin. Pp. 187-224
Hubbs, Carl L. (1955) Hybridization between fish species in nature, Systematic Zoology 4: 1-20
Jenkins, Robert E.; Burkhead, Noel M. (1993) Freshwater fishes of Virginia., , Bethesda, MD. Pp.
Johnson, James H.; Dropkin, David S. (1992) Predation on recently released larval American shad in the Susquehanna River Basin, North American Journal of Fisheries Management 12: 504-58
Jug Bay Wetlands Sanctuary (1994) Checklist of the Fish of the Jug Bay Wetlands Sanctuary, , . Pp.
Kazyak, Paul F.; Christmas, John F.; Kelly, Suzanne M.; Stranko, Scott A. (1998) Pocomoke River Basin: Environmental Assessment of Stream Conditions, , Annapolis. Pp.
Kazyak, Paul F.; Christmas, John F.; Naylor, Michael D.; Kelly, Suzanne M.; Stranko, Scott A. (1998) Choptank River Basin: Environmental Assessment of Stream Conditions, , Annapolis. Pp.
Killgore, K. Jack; Morgan, Raymond P. II; Rybicki, Nancy B. (1989) Distribution and abundance of fishes associated with submersed aquatic plants in the Potomac River, North American Journal of Fisheries Management 9: 101-111
Kirby, John M. (1982) Prey utilization among four sympatric species of sunfish, Proceedings of the Pennsylvania Academy of Science 56: 147-150
Kirk, James P.; Davies, William D. (1985) Competitive influences of gizzard shad on largemouth bass and bluegill in small impoundments, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 39: 116-124
Lazzarro, Xavier (1987) A review of planktivorous species: Their evolution, feeding behaviours, selectivties and impacts., Hydrobiologia 146: 97-167
Lazzarro, Xavier; Drenner, Ray W.; Stein, Roy A.; Smith, J. Durward (1992) Planktivores and plankton dynamics: effectgs of fish biomass and planktivore type., Canadian Journal of Fisheries and Aquatic Sciences 49: 1466-1473
Leach, Glenn H. (1921) Report on the propagation and distribution of food fishes., In: (Eds.) Report of the United States Bureau of Fisheries for 1919.. , Washington D.C.. Pp.
Lee, David S. (1976) Aquatic zoogeography of Maryland, Atlantic Naturalist 31: 147-158
Lee, David S.; Gilbert, Carter R.; Hocutt, Charles H.; Jenkins, Robert E.; McAllister, Don E.; Stauffer, Jay R. (1980) Atlas of North American Freshwater Fishes, , Raleigh. Pp.
Lee, David S.; Platania, S. P.; Gilbert, Carter R.; Franz, Richard; Norden, Arnold (1981) A revised list of the freshwater fishes of Maryland and Delaware, Proceedings of the Southeastern Fishes Council 3: 1-9
Lever, Christopher (1996) Naturalized fishes of the world., , London, England. Pp.
Lippson, Alice J.; Haire, Michael S.; Holland, A. Frederick; Jacobs, Fred; Jensen, Jorgen; Moran-Johnson, R. Lynn; Polgar, Tibor T.; Richkus, William (1979) Environmental Atlas of the Potomac Estuary, , Baltimore, MD. Pp.
Lippson, Alice J.; Moran, R. Lynn (1974) Manual for identification of early developmental stages of fishes of the Potomac River estuary., In: (Eds.) . , Baltimore MD. Pp.
Mansueti, Romeo J. (1950) An ecological and distributional study of the fishes of the Patuxent River watershed, Maryland, , College Park, Maryland. Pp.
Massmann, William H.; Ladd, Ernest C.; McCutcheon, Henry M. (1952) A biological survey of the Rappahannock River, Virginia, Virginia Fisheries Laboratory Special Scientific Report 6: 1-152
Maurakis, Eugene; Woolcott, William S.; Jenkins, Robert E. (1987) Physiographic analyses of the longitudinal distribution of fishes in the Rappahannock River, Virginia, ASB Bulletin 34: 1-14
McCrady, Ellen Joy (1990) Interactions between the invasive freshwater clam, Corbicula fluminea, and its fish predators in Lake Fairfield, Texas, , Arlington, Texas. Pp.
McGovern, John E.; Olney, John E. (1988) Potential predation by fish and invertebrates on early life history stages of striped bass in the Pamunkey River, Virginia, Transactions of the American Fisheries Society 117: 152-161
Meffe, Gary K. (1991) Failed invasion of a southeastern blackwater stream by bluegills: implications for conservation of native communities, Transactions of the American Fisheries Society 120: 333-358
Mills, Edward L.; Scheuerell, Mark D.; Carlton, James T.; Strayer, David (1997) Biological invasions in the Hudson River: an inventory and historical analysis., New York State Museum Circular 57: 1-51
Mittelbach, Gary G. (1984) Predation and resource partitioning in two sunfishes (Centrarchidae), Ecology 65: 499-513
Mittlebach, Gary G. (1988) Competition among refuging sunfishes and effects of fish density on littoral zone invertebrates, Ecology 69: 614-623
Musick, J. A.; Wiley, Martin L. (1972) Fishes of Chesapeake Bay and the adjacent coastal plain, Special Scientific Report, Virginia Institute of Marine Science 65: 175-212
Olson, Mark H. (1992) Mixed competition/predation interactions between largemouth bass and bluegill: patterns in young-of-year (YOY) growth, Bulletin of the Ecological Society of America 73: 291
Osenburg, Craig W.; Olson, Mark H.; Mittelbach, Gary G. (1994) Stage structure in fishes: resource productivity and competition gradients., , Columbia. Pp. 151-170
Page, Lawrence M.; Burr, Brooks M. (1991) Freshwater Fishes., , Boston. Pp.
Paszkowski, Cynthia A. (1986) Foraging site use and interspecific competition between bluegills and golden shiners, Environmental Biology of Fishes 17: 227-233
Peterson, Mark S. (1988) Comparative physiological ecology of centrarchids in hyposaline environments, Canadian Journal of Fisheries and Aquatic Sciences 45: 827-833
Pianka, Eric R. (1973) Niche relations of desert lizards., , Cambridge. Pp. 293-314
Radcliffe, Lewis; Welsh, W. W. (1916) A list of the fishes of the Seneca Creek, Montgomery County, Maryland Region, Proceedings of the Biological Society of Washington 29: 39-45
Raney, Edward, C.; Massmann, William H. (1953) The fishes of the tidewater section of the Pamunkey River, Virginia, Journal of the Washington Academy of Sciences 43: 424-432
Savitz, Jan (1981) Trophic diversity and food partioning among fishes associated with aquatic macrophyte patches, Transactions of the Illinois State Academy of Sciences 74: 111-120
Schwartz, Frank J. (1965) Natural salinity tolerances of some freshwater fishes, Underwater Naturalist 2: 13-15
Serafy, J. E.; Harrell, R. M. (1993) Behavioral responses of fishes to increasing pH and dissolved oxygen: field and laboratory observations, Freshwater Biology 30: 53-61
Serafy, Joseph E.; Harrell, Reginal M.; Hurley, Linda M. (1994) Mechanical removal of Hydrilla in the Potomac River, Maryland: Local impacts on vegetation and associated fishes, Journal of Freshwater Ecology 9: 135-143
Smith, Barry A. (1971) The fishes of four low-salinity tidal tributaries of the Delaware River estuary., In: (Eds.) An Ecological Study of the Delaware River in the Vicinity of Artificial Island. , Ithaca, N.Y.. Pp.
1996-2014 NMNH Fish Collection Database.. http://collections.nmnh.si.edu/search/fishes/
Wainwright, Peter C. (1996) Ecological explanation through functional morphology: the feeding biology of sunfishes, Ecology 77: 1336-1334
Wang, Johnson, C. S.; Kenehahan, Ronnie (1979) Fishes of the Delaware estuaries: a guide to the early life histories, , Towson MD. Pp.
Weaver, L. Alan, Garman, Greg C. (1994) Urbanization of a watershed and historical changes in a small fish assemblage, Transactions of the American Fisheries Society 123: 162-172
Werner, Earle E.; Hall, Donald J. (1976) Niche shifts in sunfishes: experimental evidence and significance., Science 191: 404-406
Werner, Earle E.; Hall, Donald J. (1977) Competition and habitat shifts in two sunfishes (Centrarchidae)., Ecology 58: 869-876