Lepomis macrochirus

Invasion History

First Non-native North American Tidal Record: 1855
First Non-native West Coast Tidal Record: 1908
First Non-native East/Gulf Coast Tidal Record: 1855

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General Invasion History:

The Bluegill (Lepomis macrochirus) is native to the Great Lakes and St. Lawrence and Mississippi Basins, from Quebec and New York south to the Gulf; and south on the Coastal Plain and Gulf Slope from Pee Dee or Cape Fear River basins to Rio Grande (Lee et al. 1980; Page and Burr 1991; Jenkins and Burkhead 1993). The original range of the Bluegill on the southern Atlantic Coastal Plain is uncertain because of probable early introductions. Bluegills were widely introduced by the 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 in 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 1930s to the present by many state agencies. Bluegills have been introduced into river systems in 36 states (Fuller et al. 1999), including Hawaii, and into southwestern Canada, Panama, Venezuela, South Africa, Japan, and the Philippines (Lever 1996). On the West Coast, they have been introduced to the San Francisco and Columbia River estuaries, and also into some smaller coastal estuaries (Cohen and Carlton 1995; Sytsma et al. 2004).

North American Invasion History:

Invasion History on the West Coast:

The dates of introduction of Bluegills to West Coast watersheds is uncertain, because many shipments and stockings of 'sunfishes' or 'bream' were of mixtures of species, presumably Bluegills and Green Sunfish, but possibly others (Smith 1895; Lampman 1946; Dill and Cordone 1997). Bluegills may have been released into the Willamette River in Salem, Oregon, during a stocking in 1893, or during the disposal of a large exhibit of 'spiny-rayed' fishes from the Lewis and Clark exhibition in Portland in 1905 (Lampman 1946). Some of the early plantings of Green Sunfish in Lake Cuyamaca, the Feather River, and Lake Elsinore, California in 1891 may have also included Bluegill (Dill and Cordone 1997). The first definite release of Bluegills in the San Francisco Bay watershed was in 1908, including lakes in Lassen, Placer, Lake, Sacramento, and San Joaquin counties, including the San Joaquin River at Stockton (Shebley 1917; Dill and Cordone 1895). In the Columbia River estuary, the first definite capture was in Kalama, Washington, downstream of Portland in 1930 (Chapman 1943).

The Bluegill was collected in several San Francisco Bay watershed streams by the 1940s (Leidy 2007). By 1966, Bluegill were the second most abundant centrarchid fish collected in the Delta (Turner 1966, cited by Cohen and Carlton 1995). From the 1980s to 2000, Bluegills comprised 10–30% of the total fish caught in freshwaters of the Delta (Feyrer and Healy 2003; Brown and Michniuk 2007; Grimaldo et al. 2012; Mahardja et al. 2017). However, they were rare (<1% of the total) in the fresh-brackish Suisun marsh (Matern et al. 2002). In the Columbia River basin, Bluegills seem to be rare in the mainstem of rivers (Hughes and Gammon 1987; Farr and Ward 1994), but common to abundant in lakes and sloughs (Lampman 1994; Van Dyke et al. 2009). Bluegills probably occur occasionally in smaller West Coast estuaries, but records are scarce, and may be dependent on stream flow, rainfall, dikes and barrier beaches that reduce seawater inflow, and a lower frequency of sampling. They were and probably are common in dune lakes on the Oregon Coast (Lampman 1946). Occasional specimens were captured in the Bandon Marsh National Wildlife Refuge, on the Coquille River, Oregon (Silver et al. 2017), and the Snohomish River estuary (1995, Tanner et al. 2002, 1 specimen).

Invasion History on the East Coast:

Bluegills are considered native to the southern Atlantic Slope, but the northern boundary of the native range is uncertain. It is considered probably native to the Cape Fear Rivers, North Carolina (Jenkins and Burkhead 1993). A specimen was collected in the Cape Fear River in 1877, at Wilmington, North Carolina (Smith 1907). They were apparently abundant in Albemarle Sound and Roanoke Rivers by 1907, but Hugh Smith makes no mention of introductions, although he was a leader of the US Fisheries Commission. The earliest record on the Northeast coast was a collection in the Hudson River in 1855 (Smith and Lake 1990; Daniels et al. 2005). Another early record was in the Delaware River, near Trenton, New Jersey, in 1871 (Abbott 1977). Bluegills may have been introduced with Smallmouth Bass (Micropterus dolomieu), already established in the river (Abbott 1877). As on the West Coast, there were many stockings of mixed sunfishes and 'bream', so precise records of stocking are absent.

In the Potomac River, Bluegill were first reported 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 (Anacostia River)' (Bean and Weed 1911). The first verified voucher specimen was collected in 1916 (Jenkins and Burkhead 1993). Bluegill were present in the upper Susquehanna in New York State by 1936 (Greeley 1936), and abundant in lower Susquehanna (PA) by 1961 (Bielo 1963). In other Chesapeake tributaries, first records occurred later: James-1945; York-1938; Rappahannock-1938 (Jenkins and Burkhead 1993); Patuxent River- 1940s, 'mostly in impoundments where it has been stocked' (Mansueti 1950). '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. Bluegills were collected in upper Chesapeake Bay in 1933 ('near Rock Hall', Kent Co/MD/Swan Creek, Academy of Natural Sciences of Philadelphia 2000), although missed in other surveys. The first published catch records for the Upper Bay (1958) are a creel survey in Northeast River (Elser 1960). Bluegills were rare to common in brackish tributaries (Curtis Creek to Rhode River), but less abundant than Pumpkinseeds (Carmichael et al. 1992; Hines et al. unpublished data). In Maryland Department of Natural Resources surveys, Bluegills are 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)

Bluegills were first reported from the state of Connecticut in 1942, and were well established in the tidal Connecticut River by 1965 (Whitworth 1968; Marcy 1976; Jacobs et al. 2004). Bluegills are established in many smaller New England estuaries, including the Thames River, Connecticut (Jacobson 1980), the Pettaquamscutt River estuary (Rhode Island, Narragansett Bay, Paul Fofonoff, personal observations), the Taunton River estuary (Narragansett Bay, Marine Research Inc. 1992); Slocum River (Buzzards Bay, Massachusetts, Hoff and Ibarra 1977), and the Merrimack River (Massachusetts, Peterson 1975). The tidal freshwater and low-salinity space available for these populations fluctuates with rainfall and river flow.
 

Invasion History in Hawaii:

Fourteen Bluegills were brought from California and were planted in a pond near Kaneohe Bay, Oahu, and became established. They were later transferred to all the major islands (Brock 1960). There have been later imports to island reservoirs (Maciolek 1984; Lever 1996).

Invasion History Elsewhere in the World:

Bluegills have been introduced to at least 22 countries, and are established in at least 15 (Froese and Pauly 2018). They are introduced and established in Puerto Rico in 1915, where they colonized the Cartagena Lagoon (~1957), but were later replaced by Mozambique Tilapia (Lever 1996). Bluegills were stocked in Gatun Lake, of the Panama Canal, but did not become established. Bluegills were later introduced to inland lakes in Panama, where they did become established (Lever 1996). They are established in Venezuela, and outside their native range in Mexico (Lever 1996; Froese and Pauly 2018).

Bluegills were introduced to South Africa in 1938 for recreational fishing and as forage of previously stocked Largemouth Bass (Micropterus salmoides). They are established in interior regions of South Africa, but are apparently rare or absent in coastal rivers. They have also been introduced to Swaziland and Zimbabwe (Lever 1996). In 1960, 15 Bluegill from Iowa were placed in a hatchery in Japan and their offspring were stocked in many lakes in Japan. By 2004 they were found throughout the country. All of the Bluegill in Japan are descended from the original stock. Although genetic diversity is low, populations have showed high phenotypic plasticity (Kawamura et al. 2010). In 1969, Bluegills from Japan were introduced to South Korea for aquaculture, but soon became established in the wild (Lever 1996).

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Description

The Bluegill (Lepomis macrochirus) is a medium-sized freshwater fish. Fishes of the family Centrarchidae (Sunfishes and Black Basses) have a strongly 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. The sunfishes of the genus Lepomis have a shallowly forked tail, a smooth edge to the gill cover, and a fleshy 'ear-flap' projecting from the gill-cover. The gill-cover has a thin, flexible rear edge. Bluegills have a deep, strongly compressed, oval body, a small terminal mouth (not extending to the pupil of the eye), and long, pointed pectoral fins, which extend far past the eye when bent forward. The dorsal fin has 9–12 spines and 10–13 rays, while the anal fin has 3 spines and 9–12 rays. There are 38–46 lateral line scales. The maximum length is 410 mm, but a more usual length is 100–180 mm. The back is olive, with yellow and green flecks on the upper side, and 5–6 vertical dark bars, which are broad in adults, but thin and chainlike in juveniles. The ear-flap is black to the edge. There is a large black spot on the rear edge of the dorsal fin, and often a dusky spot on the anal fins. The gill-cover has two blue streaks running from the chin to the edge. The belly is white-to-yellow, and the fins range from transparent to dusky. A breeding male has an orange breast, and a blue head and back. Young and female fish have chain-like dark bars on the side (Hardy 1978; Page and Burr 1991; Jenkins and Burkhead 1993; Murdy et al. 1997; Moyle 2002).

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Taxonomy

Ecology

General:

The Bluegill (Lepomis macrochirus) is a freshwater fish that also enters brackish water (Murdy et al. 1997). Adults mature at 1–2 years, at 75–100 mm in a stunted population, but more typically at 100–150 mm (Hardy 1978). Spawning takes place at 17–27 °C in freshwater (Hardy 1978; Wang 1986; Jenkins and Burkhead 1993; Moyle 2002). Males excavate and guard a nesting site, in shallow water, in sand or gravel, often nesting colonially, but guarding their nests individually. Males may spawn with several females, and guard the nests until they hatch. Females can carry 2540–64,000 eggs. Eggs hatch in 1.5–3.5 days at 18.5–28.0 °C. When the yolk-sac is absorbed, the larvae leave the nest and begin feeding on zooplankton (Hardy 1978; Jenkins and Burkhead 1994; Moyle 2002).

Bluegills inhabit a wide range of freshwater habitats, including ponds, pools, small rivers, and can tolerate a wide range of temperatures, 5–33.5 °C (Hardy 1978; Moyle 2002). It appears to be more tolerant of ice-cover and long winters than many other sunfishes, based on its native range (Page and Burr 1991; Lever 1996). In estuaries on the East Coast, it ranges into brackish water. It has been collected at 10–12 PSU in the Rhode River, a Chesapeake tributary (Hines et al., personal communication), and at 18.0 PSU in the lower Potomac (Hardy 1978; Murdy et al. 1997). Habitats include vegetated lakes and ponds, pools of creeks, small rivers and tidal creeks (Hardy 1978; Jenkins and Burkhead 1994; Moyle 2002; Murdy et al. 1997). Young Bluegills are planktivores, while adults shift to aquatic insects, terrestrial insects, small crustaceans, snails, and small fishes (Jenkins and Burkhead 1994; Moyle 2002). Common predators include larger fishes, such as bass and catfish, birds, and humans (Murdy et al. 1997).

Food:

Zooplankton, plants, insects, invertebrates

Consumers:

fished, humans

Competitors:

Other sunfishes

Trophic Status:

Carnivore

Carn

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Habitats

General Habitat	Nontidal Freshwater	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Grass Bed	None
General Habitat	Coarse Woody Debris	None
General Habitat	Swamp	None
General Habitat	Unstructured Bottom	None
General Habitat	Canals	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Salinity Range	Mesohaline	5-18 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Nektonic	None

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Life History

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	5	Field, Hardy 1978
Maximum Temperature (ºC)	35	Field, Hardy 1978
Minimum Salinity (‰)	0	This is a freshwater species
Maximum Salinity (‰)	18	Field, Schwartz 1965. However, in experiments fish died ar 14–18 PSU (Smith 1971).
Minimum Dissolved Oxygen (mg/l)	1	Moyle 2002
Minimum pH	4	Field, Hardy 1978
Maximum pH	10.4	Field, Hardy 1978
Minimum Reproductive Temperature	27	Field, Hardy 1978
Maximum Reproductive Temperature	35	Field, Hardy 1978
Minimum Length (mm)	48	Size at first reproduction, male, female- 48 mm (Hardy 1978)
Maximum Length (mm)	410	Page and Burr 1991, but a more usual length is 100–180 mm (Hardy 1978; Jenkins and Burkhead 1993)
Broad Temperature Range	None	Cold Temperate-Subtropical
Broad Salinity Range	None	Limnetic-mesohaline

General Impacts

The Bluegill (Lepomis macrochirus) is a tolerant, adaptable, fast-reproducing fish, which has been widely introduced as a gamefish and a forage fish (mostly for introduced Black Basses, Micropterus spp.) It is popular as a game fish for food and sport, but also has a tendency to overpopulate and become stunted, especially in small ponds (Jenkins and Burkhead 1993; Lever 1996; Moyle 2002). In California, it may have contributed to the decline of the native Sacramento Perch (Archoplites interruptus) through competition or predation on eggs and larvae (Marchetti 1999). Hybrids have been noted with Pumpkinseed, Green Sunfish, and Warmouth (Hubbs 1955; Jenkins and Burkhead 1993; Moyle 2002).

Economic Impacts

Fisheries- Bluegills are a popular sport fish, well regarded as a 'pan-fish' which can easily be caught by children with minimal equipment. However, especially in small bodies of water, it is prone to developing dense populations of stunted fish. It is also a potential predator on eggs and larvae of more desirable game-fishes (Lampman 1946; Murdy et al. 1997; Moyle 2002). A major reason for their introduction in Japan and South Africa has been as forage for introduced North American 'Black Basses' Micropterus spp. (Lever 1996).

Ecological Impacts

Bluegills are fast-reproducing fishes, which are strong competitors, and potential predators on eggs and larvae of other fishes. In South Africa and Japan, they were introduced as forage for introduced North American 'Black Basses' (Micropterus spp.). The impacts of basses and sunfishes are difficult to separate, but the two groups of fishes together have had negative effects on native fishes in South Africa and Japan (Lever 1996; Yonekura et al. 2005).

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Regional Impacts

P090	San Francisco Bay		Ecological Impact	Competition
Introductions of Bluegill and other introduced centrarchids are blamed for the virtual elimination of the Sacramento Perch (Archoplites interruptus), a native centrarchid, from its native habitats in California, through the Bluegill's aggressive behavior in feeding, nesting, and use of cover (Moyle 1976; Marchetti 1999; Moyle 2002).
P090	San Francisco Bay		Ecological Impact	Predation
In the eastern Sacramento-San Joaquin Delta (North Fork Mokelumne River), experimental removal of predators (probably mostly Bluegill and Largemouth Bass), increased survival of tagged, migrating juvenile Chinook Salmon (Oncorynchus tshawytscha (Cavallo et al. 2013).
M130	Chesapeake Bay		Ecological Impact	Predation
Predation- Juvenile Bluegill fed heavily on Striped Bass larvae (Morone saxatilis) in experiments. This species was abundant in larval nursery areas in the tidal Pamunkey River VA (McGovern and Olney 1988). Bluegills also fed on newly stocked shad (Alosa sapidissima larvae in the nontidal Susquehanna River, Pennsylvania (Johnson and Dropkin 1992).
M130	Chesapeake Bay		Economic Impact	Fisheries
Fisheries - Bluegill 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 Pumpkinseed and Redbreast Sunfish (L. auritus). However, Bluegill is apparently less abundant than Pumpkinseed 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.
P090	San Francisco Bay		Economic Impact	Fisheries
Bluegills are a very popular gamefish in California, but are prone to stunting due to rapid reproduction and crowding (Moyle 2002).
P260	Columbia River		Economic Impact	Fisheries
Bluegills were (and still are) highly regarded pan-fish for fight and flavor, but are prone to stunting (Lampman 1946).
CA	California		Ecological Impact	Competition
Introductions of Bluegill and other introduced centrarchids are blamed for the virtual elimination of the Sacramento Perch (Archoplites interruptus), a native centrarchid, from its native habitats in California, through the Bluegill's aggressive behavior in feeding, nesting, and use of cover (Moyle 1976; Marchetti 1999; Moyle 2002).
CA	California		Ecological Impact	Predation
In the eastern Sacramento-San Joaquin Delta (North Fork Mokelumne River), experimental removal of predators (probably mostly Bluegill and Largemouth Bass), increased survival of tagged, migrating juvenile Chinook Salmon (Oncorynchus tshawytscha (Cavallo et al. 2013).
CA	California		Economic Impact	Fisheries
Bluegills are a very popular gamefish in California, but are prone to stunting due to rapid reproduction and crowding (Moyle 2002).

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