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(Alternanthera philoxeroides)
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White Perch
Photo credit: © Robert Aguilar,
Smithsonian Environmental Research Center
(Morone americana)
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Species at a Glance
The white perch, also called the silver perch and the stiffback, is not actually a perch but rather a member of the temperate bass family. It is a prolific competitor of native fish species and is believed to have the potential to cause declines of Great Lakes walleye populations.
Identification
Its deep, laterally compressed body, which averages in length from 13-18 cm (5.1-7 in), is steeply sloped from the dorsal origin to the nose. The mouth is large and extends just below the eye, and the tongue lacks teeth. The dorsal fin is made up of a spiny and soft portion separated by a deep notch and a small membrane. Color is silvery-gray to greenish-brown above, fading to silvery-white below and paler on the sides, with no lateral line.
Similar Species
The white perch is most similar to the white bass (Morone chrysops), which grows larger, is more uniformly silver with prominent dark horizontal stripes, and lacks the connected membrane between the first and second dorsal fins. Hybridization between the two species has been documented in Lake Erie, which has resulted in mixed characteristics.
Habitat
This predacious and opportunistic feeder thrives in brackish and freshwater rivers, streams, and lakes. It exploits shallow and deep water, and can overpopulate quickly.
Spread
Spread has occurred through natural dispersal, unauthorized stockings, and recreational activities. Additional spread may occur as the white perch is stocked as a sport fish in many areas of the Mississippi River watershed.
Distribution
The white perch is native to the Atlantic coastal regions of the United States, including the Lower St. Lawrence River south to South Carolina. It invaded the Great Lakes through the Erie and Welland canals in 1950 and is now found in all of the Great Lakes. In Pennsylvania it is established in Lake Erie, the Monongahela and Allegheny rivers, and has been found in several inland lakes throughout the state. This species is native in the lower Delaware and lower Susquehanna rivers.
Note: Distribution data for this species may have changed since the publication of Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015), the source of information for this description.
*To learn more about the native/invasive range of White perch in Pennsylvania, check out the information available for this species on our Invasive Here but Not There page.
Environmental Impacts
The diet of the white perch, which includes zooplankton, insect larvae, and other fishes, puts it in direct competition with native game and forage species for food. In the spring, white perch feed heavily on the eggs of other fish species such as walleye and white bass, limiting recruitment and causing declines in species numbers.
Note
Information for this species profile comes from Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015).