Redspotted sunfish, dwarf sunfish, pygmy sunfish, sunperch

L. humilis was first recorded in the Great Lakes Basin in 1929 at Lake St. Mary’s State Park in Ohio; by the 1940s it had spread to the Maumee River and other Lake Erie river systems (Emery, 1985).

L. humilis breeding season is during the summer. L. humilis construct round nests in gravel to lay their eggs; males guard and fan eggs until fry emerge (Barney and Anson, 1923). Females may lay as many as 4,700 eggs (Barney and Anson, 1923).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic	Beneficial

Current research on the environmental impact of Lepomis humilis in the Great Lakes is inadequate to support proper assessment.

Potential:
It is possible that the orangespotted sunfish competes for food with native fishes such as young bass (Micropterus spp.), bluegill (L. macrochirus), and crappie (Pomoxis spp.) (Cross 1967).

There is little or no evidence to support that Lepomis humilis has significant socio-economic impacts in the Great Lakes.

Potential competition with native sport fishes may inhibit recreation.

Current research on the beneficial effects of Lepomis humilis in the Great Lakes is inadequate to support proper assessment.

Potential:
Although closely related to bluegill, orangespotted sunfish is not considered an important sportfish in the southern U.S., where many populations are native (Hassan-William and Bonner n.d.). L. humilis may act as a forage fish for economically important sport fishes such as bass (Micropterus spp.) or members of the Esox genus (Barney and Anson, 1923); however there are numerous species of native fishes that serve the same purpose.

L. humilis was originally listed in Canada under the Species at Risk Act (SARA), but it was removed once its native status was revised (COSEWIC, 2008) There are not currently any regulations specific to this species in the Great Lakes Region.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
Predatory fish such as bass (Micropterus spp.) consume L. humilis (Barney and Anson, 1923). Restricting harvest of predatory fish in bodies of water where L. humilis are established may help to control their populations.

Physical
Physical barriers such as dams may prevent the dispersal of L. humilis.

Chemical
Of the four chemical piscicides registered for use in the United States, antimycin A and rotenone are considered “general” piscicides, but no studies have been found of their effects on Lepomis humilis (GLMRIS 2012).

Increasing CO2 concentrations, either by bubbling pressurized gas directly into water or by the addition of sodium bicarbonate (NaHCO3) has been used to sedate fish with minimal residual toxicity, and is a potential method of harvesting fish for removal, though maintaining adequate CO2 concentrations may be difficult in large/natural water bodies (Clearwater et al. 2008). CO2 is approved only for use as an anesthetic for cold, cool, and warm water fishes the US, not for use as euthanasia, and exposure to NaHCO3 concentration of 142-642 mg/L for 5 min. is sufficient to anaesthetize most fish (Clearwater et al. 2008).

It should be noted that chemical treatment will often lead to non-target kills, and so all options for management of a species should be adequately studied before a decision is made to use piscicides or other chemicals. Potential effects on non-target plants and organisms, including macroinvertebrates and other fishes, should always be deliberately evaluated and analyzed. The effects of combinations of management chemicals and other toxicants, whether intentional or unintentional, should be understood prior to chemical treatment.  Other non-selective alterations of water quality, such as reducing dissolved oxygen levels or altering pH, could also have a deleterious impact on native fish, invertebrates, and other fauna or flora, and their potential harmful effects should therefore be evaluated thoroughly.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Possibly native to the Lower Great Lakes (particularly the southern ends Lake Michigan), but currently the confirmed native range is just outside the basin boundary.