Species in the genus Morone are generally deep bodied fishes with complete lateral lines, ctenoid scales, and an opercular spine. Their jaws contain conical, villiform teeth which are set close together. The pelvic fin contains 1 spine and 5 rays, the caudal fin has 17 principal rays, and there are 7 branchiostegal rays, 3 anal spines, and 2 dorsal fins, one with 9 spines and the other with 1 spine and 10-14 soft rays. has a silvery green-gray or dark color above with silver or brass sides and a white underside. During spawning the underside of the mandible may be a pink or blue to purplish color. Often the caudal and pelvic fins have a reddish colored base. The body is oblong and dorsoventrally compressed with a depressed head, and a pointed nose with an oblique terminal mouth and a projecting jaw. Teeth are small, pointed, and banded on the jaw. The dorsal fins are hardly connected and about equivalent in length. differs from other members of the genus by the dorsal fin connection being so slight, by having no teeth on the base of the tongue and no lateral stripes, by and the anal spines being ungraduated. (Etnier and Starnes, 1993; Stanley and Danie, 1983)
White perch development consists of four stages: embryonic, larval, juvenile, and adult. The embryonic stage is short and begins directly after fertilization. The young develop within a mature egg for 30 to 108 hours depending upon water temperature, where warmer water reduces the incubation period.
The larval stage begins at hatching and is divided into two stages: prolarval and postlarval. Upon hatching, prolarvae measure 1.7 to 3.0 mm in length, and stay in the place they were spawned for 4 to 13 days. They lack pigmentation in the eyes and are not very mobile. Later in the prolarval stage, larvae grow to 3 to 4 mm and begin to swim up or down in the water column, resulting in dispersal due to water currents. Older and larger individuals seek deeper waters. Prolarvae move into the postlarval stage when they develop mouths and coloration in the eyes, and average 3.8 mm in length. Postlarvae continue to grow and develop but are sensitive to temperature fluctuations and water salinity up to 3 to 5 ppt.
When larvae produce fins and grow to total lengths of 7 to 9 mm, they are dubbed juveniles. Juveniles stay close to shore and use creeks and rivers as nurseries. They prefer demersal habitats, living in muddy and silty waters containing aquatic plants. They may stay in these areas for up to a year and reach lengths of 20 to 30 mm, but remain reproductively immature until 2 to 4 years of age, when males are 72 to 80 mm long and females 90 to 98 mm.
Growth rate and size are determined by several external limiting factors such as temperature, precipitation, food availability, and competition. The most growth occurs during the first year of life, and it is then that external factors are most influential. White perch grow slowly and are often stunted when population densities are high. It is also a common trend for warmer water with less rainfall to produce faster growing individuals. (Stanley and Danie, 1983)
White Perch are anadromous fish which spawn once yearly. They prefer freshwater bodies but are fairly diverse in spawning habitat. They can reproduce in water with salinity levels as high as 4.2 ppt, in tidal or non tidal, clear or murky, slow moving or fast waters. The lack of a need for specialized breeding habitat allows them to reproduce in almost any water system, from lakes and ponds to estuaries or rivers. Spawning always occurs in water less than 7.01 m deep. Individuals tend to spawn in estuarine waters 0.91 m to 6.10 m deep, lake waters up to 1.52 m deep, and in marshes up to 3.66 m deep.
Diversity of breeding habitat allows many M. americana to spawn in the same waters they normally inhabit. However, some populations travel up to 104.61 Km to spawn, and all marine populations must migrate to waters within the proper salinity constraints. Spawning behavior is triggered by temperature fluctuations in early spring. Populations can be split into four major periods of spawning. The Northern populations spawn from March to early April, while the Southern are later. Estuarine populations spawn from May through July, and freshwater populations from April to May.
During spawning there may be two or three different periods of ripe egg release, generally at dusk or after rain. Fecundity for small females (151 to 160 mm fork length) averages 21,180 eggs per individual, and for larger females (241 to 250 mm fork length) 234,342 eggs. At release, the eggs adhere to the substrate or can stick to each other and be free-floating. After the eggs reach maturity they hatch at different intervals determined by water temperature; at 20˚ C they hatch in 30 hrs, at 18˚C hatch within 50 hrs, and at 15˚ C between 96 and 108 hrs. The hatcheries are not gaurded and larvae are independant upon hatching. (Heemstra, 2002; Stanley and Danie, 1983)
Adults do not guard eggs and no parental care is provided for the larvae. The largest energy expenditure in reproduction occurs if an individual migrates to spawn. (Heemstra, 2002; Stanley and Danie, 1983)
Little is known about the lifespan of M. americana. However, closely related species such as river perch, european perch, and largemouth bass live up to 15 to 25 years. ("Animal Diversity Web Site", 1995)
Juveniles often aggregate in shoals and in creek and river backwaters, using them as nurseries. They may move outside of the nursery to feed, and return to it at night. As water temperatures fall, juveniles move to brackish water and submerge themselves in deep pools to over-winter.
Adults exhibit this same behavior in winter weather. As temperatures rise in spring they move toward their spawning grounds, which are usually upstream in shallower freshwaters. After spawning they move back into deeper water for the summer months. (Stanley and Danie, 1983)
No information indicates white perch as a territorial species, and when not migrating to their spawning grounds they tend to move within a perimeter of 19 km. (Stanley and Danie, 1983)
There is little information available on communication in M. Americana. It is able to perceive its environment using vision, hearing, chemoreception and detection of vibrations by the lateral line system. (Etnier and Starnes, 1993)
White perch are primarily piscivorous, feeding on other fish such as those in the families Cyprinidae and Osmeridae. Other major components of the diet of M. americana are fish eggs and larvae, annelids, insects, some crustaceans, and detritus.
Larval white perch feed off of zooplankton. As they grow, they tend to eat larger zooplankton and insects in spring, and as these populations wane their diet switches to larval fish, eggs, detritus, and crustaceans, and in some areas shrimp, squid, and crabs. Once white perch grow to 22 cm they eat almost nothing but other fish. (Heemstra, 2002; Stanley and Danie, 1983)
Predation usually occurs within the embryonic and larval stages, but is not uncommon in the juvenile stage. It is less common in the adult stage. Of the recognized predators, Morone saxatilis (striped bass), Sander vitreus (walleye), Pomatomus saltatrix (bluefish), and Cynoscion regalis (weakfish) prey mainly on juveniles and adults. (white perch), Lepomis macrochirus (bluegill), and Cyclops bicuspidatus (a copepod), are mainly larval and egg predators.
Because of the low degree of predation on adults, white perch do not show strong camouflage or avoidance techniques. The adaptation that appears most important is the large number of eggs produced during spawning. (Heemstra, 2002; Stanley and Danie, 1983)
As an important predator on a large number of species and an important prey species of some fish, copepods and terrestrial vertebrates, white perch fill many roles within their environment depending on age, size, competition, and season. They occupy different depths and are opportunistic feeders. (Stanley and Danie, 1983)
These fish have become a favorite food source for humans. White perch are important both commercially and as a popular sport fish. The commercial industry is strongest from Massachusetts to North Carolina, being the most popular in the Chesapeake Bay area. No commercial fishing takes place in the northern and southern-most edges of their range. White perch harvest is accomplished by trawl, haul seines, and drift gill nets, and occurs all year, with the best results during the spring. In 1979, Maryland had the greatest harvest during a single year, yielding 563 metric tons of perch.
Sport fishing is popular in both marine and fresh waters throughout the species' range except in the gulf of Maine. Marine populations are most heavily utilized in Mid-Atlantic States, and an estimated 5,494,000 fish were caught by recreational fisherman in 1979. Freshwater sport fishing of white perch is most common in the northern portion of its range, where in 1979 Maine had an estimated catch of 60,175,000 and New Hampshire 664,000. (Etnier and Starnes, 1993; Stanley and Danie, 1983)
As invasive piscivores, white perch have been implicated in changes to some Great Lakes fisheries, such as white bass and walleye. ("White perch", 2002)
The lack of habitat restrictions, diversity of food sources, high fecundity rates, and generalist behavior white perch exhibit give them a competitive edge over many other species. They easily colonize new areas and utilize the available food sources better than native populations. Therefore, a need to has never arisen to protect M. americana. The species has no special conservation status, and its populations are doing quite well. (Heemstra, 2002; Stanley and Danie, 1983; Heemstra, 2002; Stanley and Danie, 1983)
Recorded infections in Connecticut of Epitheliocystis Bacterial Diseases are the only listed diseases affecting white perch. (Heemstra, 2002)
Aaron Martens (author), Eastern Kentucky University, Sherry Harrel (editor, instructor), Eastern Kentucky University.
Mary Hejna (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
marshes are wetland areas often dominated by grasses and reeds.
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
University of Michigan. 1995. "Animal Diversity Web Site" (On-line). Class Actinopterygii. Accessed October 26, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Actinopterygii.html.
University of Wisconsin Seagrant Institute. 2002. "White perch" (On-line). Fish of the Great Lakes. Accessed September 23, 2006 at http://www.seagrant.wisc.edu/greatlakesfish/whiteperch.html.
Etnier, D., W. Starnes. 1993. The Fishes of Tennesse. Knoxville: The University of Tennesse Press.
Heemstra, P. 2002. "Fish Base" (On-line). Morone americana. Accessed October 24, 2005 at http://www.fishbase.org/Summary/speciesSummary.php?ID=355&genusname=Morone&speciesname=americana.
Jackson, L., C. Sullivan. 1995. Reproduction of White Perch: The Annual Gametogenic Cycle. Transactions of the American Fisheries Society, 124: 563-557.
Stanley, J., D. Danie. 1983. "White Perch" (On-line). Accessed October 23, 2005 at http://www.nwrc.usgs.gov/wdb/pub/0199.pdf.