Morone americana

Geographic Range

Morone americana (white perch) is found along the Atlantic coast area of the Nearctic region, ranging from the coastal areas of New Jersey as far south as South Carolina. The species has been introduced into inland bodies of water in New England and some of Nebraska’s waters as well as Lakes Ontario and Erie.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native

Habitat

Morone americana inhabits mainly brackish water and estuaries such as the Chesapeake Bay. Members of the same genus ( Morone ) reside in large bodies of water such as lakes, reservoirs, estuaries, or bays among others.

• Habitat Regions
• temperate temperate
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• coastal coastal
• brackish water brackish water

• Wetlands
• marsh marsh

• Other Habitat Features
• estuarine estuarine

Physical Description

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. Morone americana 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. Morone americana 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.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

Development

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.

Reproduction

Morone americana is polyandrous, without mate guarding or displays of dominance. A ripe female is merely enveloped by a group of males. The sperm and eggs are released at random into the environment, where the eggs stick to one another and to the substrate, and sperm from various males fertilize them.

• Mating System
• polyandrous polyandrous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• broadcast (group) spawning
• oviparous oviparous

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.

• Parental Investment
• no parental involvement

Lifespan/Longevity

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.

Behavior

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.

• Key Behaviors
• natatorial natatorial
• motile motile
• migratory migratory

Home Range

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.

Communication and Perception

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.

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

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.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore

• Animal Foods
• fish
• eggs
• insects
• mollusks
• aquatic or marine worms
• aquatic crustaceans
• zooplankton zooplankton

• Other Foods
• detritus detritus

Predation

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), Stizostedion vitreum (walleye), Pomatomus saltator (bluefish), and Cynoscion regalis (weakfish) prey mainly on juveniles and adults. Morone americana (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.

Ecosystem Roles

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.

Economic Importance for Humans: Positive

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.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

As invasive piscivores, white perch have been implicated in changes to some Great Lakes fisheries, such as white bass and walleye.

Conservation Status

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.

Other Comments

Recorded infections in Connecticut of Epitheliocystis Bacterial Diseases are the only listed diseases affecting white perch.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Aaron Martens (author), Eastern Kentucky University, Sherry Harrel (editor, instructor), Eastern Kentucky University.

Mary Hejna (editor), University of Michigan-Ann Arbor.

References

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 .

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 .