The freshwater drum, ''Aplodinotus grunniens'', is a fish endemic to

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

. It is the only species in the genus ''Aplodinotus'', and is a member of the family

Sciaenidae Sciaenidae is a family (biology), family of ray-finned fishes belonging to the Order (biology), order Acanthuriformes. They are commonly called drums or croakers in reference to the repetitive throbbing or drumming sounds they make. The family co ...

. It is the only North American member of the group that inhabits freshwater for its entire life.Fish of the Great Lakes: Wisconsin Sea Grant. Freshwater Drum Aplodinotus grunniens. Wisconsin Sea Grant 2002.http://seagrant.wisc.edu/greatlakesfish/drum.html. Its generic name, ''Aplodinotus'', comes from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

meaning "single back", and the specific epithet, ''grunniens'', comes from a

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word meaning "grunting". It is given to it because of the grunting noise that mature males make. This noise comes from a special set of muscles within the body cavity that vibrate against the

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

. The purpose of the grunting is unknown, but due to it being present in only mature males and during the spawning season, it is assumed to be linked to spawning. The freshwater drum is also called Russell fish, shepherd's pie, gray bass,Life History Notes: Freshwater Drum
Ohio Department of Natural Resources, Division of Wildlife. Retrieved on 2007-07-14. Gasper goo, Gaspergou,Freshwater Drum (Aplodinotus grunniens)
Texas Parks and Wildlife. Retrieved on 2007-07-14. gou, grunt, grunter, grinder, gobble, and croaker. It is commonly known as sheephead and sunfish in parts of Canada, and the United States.

Description

The drum typically weighs . The world record was caught on Nickajack Lake in

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

, and weighed in at . The freshwater drum is frequently gray or silvery but may be more bronze or brown colored, common in the Lake Erie population. It is a deep-bodied fish with a divided

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

consisting of 10 spines and approximately 30 rays. The pectoral fins are elongate and pointed, and the lateral line extends into the caudal fin, which has a rounded or pointed margin. The eye of the freshwater drum contains a

tapetum lucidum The ; ; : tapeta lucida) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It Reflection (physics), reflects visible light back through the retina, increas ...

within the retinal pigmented epithelium, as in other sciaenids. In other sciaenids this structure has been found to contain packed lipid spherules which contribute to its reflective properties. Extensive pharyngeal tooth pads are present in upper and lower sets, with cardiform and villiform teeth gradually being replaced by molariform teeth as the fish grows larger.

Geographic distribution

Freshwater drum are the only North American member of their family to exclusively inhabit freshwater (freshwater family members in genera '' Pachypops'', '' Pachyurus'', '' Petilipinnis'' and '' Plagioscion'' are from South America, while '' Boesemania'' is Asian). Their great distribution range goes as far north as the

Hudson Bay Hudson Bay, sometimes called Hudson's Bay (usually historically), is a large body of Saline water, saltwater in northeastern Canada with a surface area of . It is located north of Ontario, west of Quebec, northeast of Manitoba, and southeast o ...

, and reaches as far south as

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

. Their longitudinal distribution goes as far east as the eastern

Appalachians The Appalachian Mountains, often called the Appalachians, are a mountain range in eastern to northeastern North America. The term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain ...

and stretches as far west into

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...

, and

Oklahoma Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...

. Freshwater drum are considered to be one of the most wide-ranging species in North America.

Ecology

The freshwater drum prefers clear water, but it is tolerant of turbid and murky water. They prefer the bottom to be clean sand and gravel substrates.Ohio Department of Natural Resources. Freshwater Drum. Ohio Department of Natural Resources 2011. http://www.ohiodnr.com/Home/species_a_to_z/SpeciesGuideIndex/freshwaterdrum/tabid/6634/Default.aspx. The diet of the freshwater drum is generally

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

and composed of

macroinvertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum V ...

s (mainly aquatic insect larvae and bivalve mussels), as well as small fish in certain ecosystems. Freshwater drum show distinct seasonal differences in their diet. In April and May, the drum feeds on

dipteran Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

s. During these months, dipterans make up about 50 percent of the freshwater drum's diet.Griswold, Bernard L and R.A. Tubb. 1977. Food of Yellow Perch, White Bass, Freshwater Drum, and Channel Catfish in Sandusky Bay, Lake Erie. Ohio Journal of Science. Volume 43, Issue 1, 1977. In August through November, they tend to eat fish (which are primarily young-of-the-year Gizzard shad). The percentage of fish in their diet at this time ranges from 52 to 94 percent. Other items in the drum's diet are mollusks and crayfish. The freshwater drum competes with several organisms. During its early stages in

Lake Erie Lake Erie ( ) is the fourth-largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and also has the shortest avera ...

, it has been shown to compete with

yellow perch The yellow perch (''Perca flavescens''), commonly referred to as perch, striped perch, American perch or preacher is a freshwater perciform fish native to much of North America. The yellow perch was described in 1814 by Samuel Latham Mitchill fr ...

, the

trout-perch ''Percopsis omiscomaycus'', also known as the trout-perch, the grounder or the sand minnow, is one of two species in the family Percopsidae. Its name comes from the Greek root words ''perc'', meaning perch and ''opsi'' meaning appearance. The spe ...

, and the emerald shiner.Daiber, Franklin C. 1952. The Food and Feeding Relationships of the Freshwater Drum, ''Aplodinotus grunniens'' Rafinesque in Western Lake Erie. The Ohio Journal of Science. v52 n1 (January, 1952), 35–46. During its adult lifetime, it competes with yellow perch and

silver chub The silver chub (''Macrhybopsis storeriana'') is a species of freshwater Actinopterygii, ray-finned fish belonging to the Family (biology), family Leuciscidae, the shiners, daces and minnows. This species is found in North America. Description ...

in deep water, and competes with

black bass Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''Psy ...

in the shoal areas. Predators on drum include humans and other fish. During its first year, the freshwater drum serves as a

forage fish Forage fish, also called prey fish or bait fish, are small pelagic fish that feed on planktons (i.e. planktivores) and other small aquatic organisms (e.g. krill). They are in turn preyed upon by various predators including larger fish, seabirds ...

for many species of predatory fish. These include

smallmouth bass The smallmouth bass (''Micropterus dolomieu'') is a species of freshwater fish in the Centrarchidae, sunfish family (biology), family (Centrarchidae) of the order (biology), order Centrarchiformes. It is the type species of its genus ''Micropterus ...

walleye The walleye (''Sander vitreus'', Synonym (taxonomy), synonym ''Stizostedion vitreum''), also called the walleyed pike, yellow pike, yellow pikeperch or yellow pickerel, is a freshwater perciform fish native to most of Canada and to the Northern ...

, and many other

piscivore A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted repti ...

s. After its first year, the primary predators on freshwater drum are humans. The drum is an important commercial crop on the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

, but in other areas it constitutes only a small portion of the commercial catch. Consistent with other sciaenids, freshwater drum are strongly nocturnal with the bulk of most catches being derived from night angling/sampling. Commercial fisheries are present for this species, although market price tends to be quite low. Thus, many freshwater drum are harvested as bycatch from targeted higher-value species. There has been some research on the freshwater drum's impact on the invasive

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...

in northern lakes and rivers. Zebra mussels are consumed by freshwater drum once they reach a length of , but drum under in length only eat small mussels and reject the larger ones.Morrison, Todd, W.E. Lynch, and K. Dabrowski. 1997. Predation of Zebra Mussels by Freshwater Drum and Yellow Perch in Western Lake Erie. Ohio State University. The fish larger than exhibit less selectivity and consume mussels relative to their availability in lakes. These larger fish are not restricted by their ability to crush zebra mussels, but they are restricted by the size of the clumps that they can remove. The drums' eating of zebra mussels contributes to a high mussel mortality, but not enough to have an impact on their spread, or control the population.

Life history

During the summer, freshwater drums move into warm, shallow water that is less than deep.Bur, Michael T. 1984. Growth, Reproduction, Mortality, Distribution, and Biomass of Freshwater Drum in Lake Erie. Journal of Great Lakes Research. Volume 10, Issue 1, 1984, Pages 48–58. The freshwater drum then

spawn Spawn or spawning may refer to: * Spawning, the eggs and sperm of aquatic animals Arts, entertainment and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** ''Spawn: Armageddon' ...

during a six to seven-week period from June through July when the water reaches a temperature of about .Swedberg, Donald V. and C.H. Walburg. Spawning and Early Life History of the Freshwater Drum in Lewis and Clark Lake, Missouri River. Transactions of the American Fisheries Society. Volume 99, Issue 3, 1970. During the spawn, females release their eggs into the water column and males release their sperm. Fertilization is random. Males generally reach sexual maturity at four years, whereas females reach maturity at five or six years. Females from six to nine years old have a clutch size of 34,000 to 66,500 eggs and they spawn in open water giving no parental care to their larvae. The eggs then float to the top of the water column and hatch between two and four days. Due to the broadcasting of eggs in open water and lack of parental care, many eggs and larvae fall victim to predation upon hatching, the pro-

larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

average long. The post-larval stage begins about 45 hours after hatching and a length of is attained. Females grow at a faster rate than the males and adult characteristics start to form at a length of . Females continue to outgrow the male throughout their lives reaching a length of . Usually the freshwater drum weighs , but they can reach well over . Freshwater drums are long-lived and have attained maximum ages of 72 years old in Red Lakes,

Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

and 32 years old in the

Cahaba River The Cahaba River is the longest substantially free-flowing river in Alabama. It is a major tributary of the Alabama River and part of the larger Mobile River basin. With headwaters near Birmingham, the Cahaba flows southwest, then at Heiberger tu ...

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

. Though they can reach very old age, the average age of a freshwater drum is between 6 and 13 years. In some cases, otoliths provide such a long record of growth that they can be studied using the same techniques as those used by dendrochronologists.Richard, J.C., and A.L. Rypel. 2013. Waterbody type influences climate-growth relationships of freshwater drum. Transactions of the American Fisheries Society 142: 1308–1320.

Current management

There are few management practices for the species, and in many regions daily bag limits are unlimited. The freshwater drum is not federally or state listed by any states. Although the commercial harvest is up to 1 million pounds per year, they are in no danger of overharvest. In the Mississippi River alone, the commercial catch has reached about in recent years.Minnesota Department of Natural Resources. Fishes of Minnesota: Freshwater Drum (Sheepshead). Minnesota Department of Natural Resources 2011. http://www.dnr.state.mn.us/fish/freshwaterdrum.html. Due to its abundance, many states allow

bowfishing Bowfishing is a fishing technique that uses specialized archery equipment to impale and retrieve fish. A bowfisher will use a bow or crossbow to shoot fish through the water surface with a barbed arrow tethered to a line, and then manually retr ...

and other non-conventional means to harvest the fish.

References