Lepomis cyanellus

Invasion History

First Non-native North American Tidal Record: 1895
First Non-native West Coast Tidal Record: 1895
First Non-native East/Gulf Coast Tidal Record: 1900

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General Invasion History:

The Green Sunfish (Lepomis cyanellus) is a freshwater fish native to the Great Lakes, Hudson Bay and Mississippi Basins from New York and Ontario to Minnesota and South Dakota south to the Gulf Coast (Escambia River, Florida) south to the Rio Grande River. Its typical habitats are small streams, ponds, and backwaters (Lee et al. 1980; Page and Burr 1991; Jenkins and Burkhead 1993). This fish was probably widely introduced by United States Fish Commission and state fish commissions in mixtures recorded as 'Sun-Fish' or 'Bream'. They are introduced in much of United States and Canada, and parts of Europe (Carlander 1977; Dill and Cordone 1997; Hardy 1978; Page and Burr 1991). In the United States they were introduced to Nevada, Utah, and California where they are abundant, frequently displace native fishes. In the east, they were introduced in Chesapeake Bay tributaries, Delaware Bay, and Hudson River (Cohen and Carlton 1995; Fuller et al. 1999; Mills et al. 1997). Altogether, they have been introduced to 32 states, and are established in most (Fuller et al. 1999; USGS Nonindigenous Aquatic Species Program 2018).

North American Invasion History:

Invasion History on the West Coast:

In 1891 to 1895 The US Fish Commission stocked many ponds and streams in Washington and California with mixtures of Green Sunfish and Bluegills (L. macrochirus), and possibly other species. Eighteen fish were stocked in the Bolso Chica River. Additional plantings were made in Lake Elsinore, San Jacinto County, and Cuyamaca Lake (Smith 1895). The early history of 'sunfish' in California is obscure because of the confusion among species. Dill and Cordone (1997) cite recollections of fisheries biologists who saw Green Sunfish and Bluegills in the San Joaquin River between 1908 and 1917. Green Sunfish were probably widely introduced by fishermen transplanting Bluegills from one stream or lake to another and are now widespread in low-elevation waters in California. They are found in watershed streams, including Suisun Creek Walnut-San Ramon Creek (1945), and San Francisquito Creek in 1940-1956 (Leidy 2007), and was present in the Delta by 1963 (Cohen and Carlton 1995). Its habitats include creeks, ponds, ditches, sloughs and reservoirs, such as lower portion of Walnut Creek; Napa River near spillway (Wang 1986). In freshwater portions of the Delta, Green Sunfish, are common to rare, but not abundant (Feyrer and Healy 2003; Brown and Michniuk 2007). Green Sunfish were rare in the brackish Suisun marshes (Matern et al. 2002).

Green Sunfish are especially good at colonizing small bodies of water, including ponds and temporary streams (Moyle 2002). These fish have been found in many small streams in coastal Southern California (Swift et al. 1993), and have been reported from the tidal regions of several coastal streams, including the Santa Clara River, Ventura County (Lafferty and Page 1997), Malibu Creek, San Juan Creek (Orange County), inlets to Carlsbad Lagoon, and the San Diego River (USGS Nonindigenous Aquatic Species Program 2018). The occurrence of Green Sunfish in these small estuaries is likely to be very dependent on rainfall and streamflow.

We have not found reports of Green Sunfish from the tidal Columbia or Willamette Rivers (Hughes and Gammon 1984; Farr and Ward 1994; Systma et al. 2004; Van Dyke et al. 2008). However, it was found in Blue Lake, Portland, a few kilometers from the Columbia River (Wydoski and Whitney 1973, cited USGS Nonindigenous Aquatic Species Program 2018).

Invasion History on the East Coast:

The earliest record of the Green Sunfish (Lepomis cyanellus) on the East Coast is in the tidal Potomac River in 1900 (Jenkins and Burkhead 1993). By 1911, they were found in large numbers in the vicinity of Chain Bridge, at the head of tide in the river (Bean and Weed 1911). It was probably introduced by United States Fish Commission with mixed batches of 'Bream' or 'Sun-Fishes' (Jenkins and Burkhead 1993). There are apparently few recent records from tidal Potomac (Lippson and Moran 1974) but these sunfish are common in the nontidal river (Jenkins and Burkhead 1993), in nontidal waters of Rock Creek and Anacostia River (Lippson et al. 1979), and nontidal creeks at Fort Belvoir, near Gunston Cove (Ernst et al. 1995). In the Susquehanna, 'Bream' were released in the Susquehanna drainage by the United States Fish Commission between 1910-1919 (Bowers 1911; Leach 1919). Green Sunfish were not listed for the Susquehanna in Pennsylvania in 1893 (Bean 1893), 1919 (Fowler 1919), or 1948 (Fowler 1948). However, they were common in the lower Susquehanna (PA) by 1961 (Bielo 1963) and collected below Conowingo Dam after 1972 (McKeown 1984, National Museum of Natural History 1996). They were also found in a creel survey in the Northeast River (Elser 1958) and are apparently common on Susquehanna Flats (Serafy et al. 1995), but rare in the Rhode River (Hines et al. unpublished). They were found in the watersheds of the Severn and Rhode Rivers (Kazyak et al. 1998).

Green Sunfish were not listed for the Delaware River by Fowler (1948) but were collected in Delaware ponds and nontidal streams beginning in 1952 (Raasch and Altemus 1991). Currently, this fish is a stray in tidal freshwater of Delaware River (Horwitz 1986; Weisberg et al. 1996). In the Hudson River drainage in 1936, Green Sunfish were found in a pond near Millwood, New York, and were reported from the main channel of the river in 1976 (Smith and Lake 1990; Mills et al. 1997). They are rare but increasing in the Mohawk River and the lower Hudson (below Troy, Daniels et al. 2005). Green Sunfish were found occasionally in the upper Thames River estuary, near Norfolk, Connecticut, in spring and summer (Jacobson et al. 1980).

Invasion History in Hawaii:

A population of Green Sunfish were discovered in a golf course pond in Kauai in 1990 but was extirpated by 1999 (USGS Nonindigenous Aquatic Species Program 2018).

Invasion History Elsewhere in the World:

Green Sunfish have established populations in Germany, Morocco, South Africa, Brazil, Korea, the Philippines, and Mauritius. Introductions to Japan and Zimbabwe have failed to establish. These introductions were made mainly as forage for introduced 'Black Basses' (Micropterus spp.) (Lever 1996).

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Description

Green Sunfish (Lepomis cyanellus) are medium-sized freshwater fish. Fishes of the genus Centrarchidae (Sunfishes and Black Basses) have laterally compressed bodies with a fused spiny and soft dorsal fin. 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 stiff rear edge. Green Sunfish have a compressed, somewhat rectangular 'bass-like' body, a large mouth (with the upper jaw extending to the midpoint of the eye), and short, rounded pectoral fins, which do not extend past the eye when bent forward. The dorsal fin has 9-12 spines and 10-12 rays, while the anal fin has three spines and 9-10 rays. There are 41-53 lateral line scales. Their maximum length is 310 mm, but they are usually 150-200 mm long. The back and sides are blue green, with yellow metallic green flecks, and dusky bars on the sides, with a white-to-yellow belly. The earflap is black, with a white margin. There is a large dark spot on the posterior dorsal and anal fins (Hardy 1978; Page and Burr 1991; Jenkins and Burkhead 1993; Moyle 2002).

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Taxonomy

Ecology

General:

Green Sunfish (Lepomis cyanellus) are freshwater fish found in ponds, backwaters, and slow-moving rivers (Page and Burr 1991; Moyle 2002). Males and females are similar in appearance, but males can mature at a smaller size (45 mm) compared to females (65 mm) (Hardy 1978), at ages as early as 6 months, in some populations, but more usually in 2-3 years. Spawning takes place at 16-28 C (Hardy 1978). Males excavate and guard a nesting site, in sand, gravel (or rarely) muck, often near vegetation or logs. Males can produce a grunting sound during mating or courting. Males are territorial and aggressive when defending nesting areas. Females can carry 2000-10000 eggs (Hardy 1978; Jenkins and Burkhead 1994). Eggs hatch in 19-50 hours at 24-28 C. Early maturation and stunting is common in crowded populations, resulting in fish that mature at 100-120 mm (Moyle 2002).

Green Sunfish inhabit a wide range of freshwater habitats, including temporary ponds, streams, and backwaters, and can tolerate a wide range of temperatures, 4-36 C (Hardy 1978; Moyle 2002). They are found mostly in tributaries at the edges of estuaries, with few records from brackish waters (Wang 1986; Peterson 1988), but they have been collected at 10-12 PSU in the Rhode River, a Chesapeake tributary (Hines et al., personal communication). Habitats include 'quiet pools and backwaters of sluggish streams, lakes, and ponds' (Page and Burr 1991) and in shallow 'sunlit waters in creeks, ponds, ditches, sloughs and reservoirs' (Wang 1986). They are generally rare in waters that contain a diverse fish community and are especially abundant in streams disrupted by human activity. They are a pioneer species, good at colonizing streams and pools with depleted fish communities (Moyle 2002). As a relatively small fish with a big mouth, they are opportunistic feeders, feeding on small aquatic insects and crustaceans as a juvenile, and incorporating larger adult insects, crayfishes, and small fishes as they grows (Jenkins and Burkhead 1994; Moyle 2002). Predators of Green Sunfish include larger fishes, such as Largemouth Bass, and humans. However, frequent stunting makes this fish a less desirable catch (Moyle 2002).

Food:

micro-crustaceans, aquatic insects, crayfish, fish

Consumers:

fishes (basses), birds, humans

Competitors:

other sunfishes (Lepomis spp.)

Trophic Status:

Carnivore

Carn

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Habitats

General Habitat	Fresh (nontidal) Marsh	None
General Habitat	Nontidal Freshwater	None
General Habitat	Swamp	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Grass Bed	None
General Habitat	Unstructured Bottom	None
General Habitat	Canals	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Nektonic	None

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	3.9	Field, Hardy 1978
Maximum Temperature (ºC)	36	Moyle 1988
Minimum Salinity (‰)	0	This is a freshwater species.
Maximum Salinity (‰)	12	Field, Rhode River, MD, Hines et al. (unpublished data).There is only one published records of Green Sunfish from brackish water (0.7 PSU, Hardy 1978, Peterson 1988).
Minimum Dissolved Oxygen (mg/l)	3	Moyle 2002
Minimum Reproductive Temperature	15.6	Field, Hardy 1978
Maximum Reproductive Temperature	28	None
Minimum Reproductive Salinity	0	This is a freshwater species.
Minimum Length (mm)	45	Males, 66 mm for females (Hardy 1978)
Maximum Length (mm)	310	Page and Burr 1991, but usually less than 200

General Impacts

Green Sunfish (Lepomis cyanellus) were widely intentionally introduced as a 'pan-fish', and unintentionally with stocked Bluegills (Lepomis macrochirus) (Smith 1895; Dill and Cordone 1997). Green Sunfish are often caught by children, but they can be regarded as a pest, because they can produce large populations of stunted fish (Jenkins and Burkhead 1994; Moyle 1992). Some of the more recent introductions of Green Sunfish have been stockings as forage fish for 'Black Basses' (Micropterus spp.) (Dill and Cordone 1997; Lever 1996). They are usually rare and peripheral in estuaries, but in tributaries they have been considered responsible for local extinctions of the California Roach (Hesperoleucus symmetricus) in the Sierra Foothills, and the Tidewater Goby (Eucyclogobius newberryi), in southern California coastal streams through predation (Lafferty and Page 1997; Moyle 2002). They are also potential predators on adults and tadpoles of California Red-Legged (Rana draytoni) and Foothill Yellow-Legged Frogs (R. boylii) (Cohen and Carlton 1995). Hybridization is common among introduced populations of sunfishes, especially in small, turbid bodies of water (Hubbs 1955; Jenkins and Burkhead 1993).

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