The channel catfish (Ictalurus punctatus),meaning “fish cat with spots”. known informally as the "channel cat", is a species of catfish native to North America. They are North America's most abundant catfish species, and the official state fish of Kansas, Missouri, Nebraska and Tennessee. The channel catfish is the most fished species of catfish in the United States, with around 8 million anglers angling them per year. The popularity of channel catfish for food has contributed to the rapid expansion of this species' aquaculture in the United States. It has also been widely introduced to Europe, Asia and South America, and many countries consider it an invasive species.
Evolution
The channel catfish appears to be a rather old species that has persisted for nearly 20 million years, as fossil remains assigned to it are abundant in numerous geological formations of central North America from the Miocene onwards. Fossil remains of the channel catfish are known from the Sheep Creek, Runningwater, Valentine, Ogallala, Ash Hollow and Seymour Formations of the United States. The oldest of these remains are known from the Middle Miocene of South Dakota. These remains were initially assigned to their own extinct species, "Ictalurus decorus" <small>Smith, 1961</small>, but later studies have found these remains to fall within the range of morphological variation of the modern channel catfish, and it has thus been synonymized with it.
Distribution and habitat
left|alt=Channel catfish|thumb|An adult channel catfish.
Channel catfish are native to the Nearctic realm and are widely distributed in southern Canada, the eastern and northern United States, and parts of northern Mexico.
They have an extensive native range consisting of almost all of the United States west of the Appalachian Mountains and east of the Rocky Mountains, roughly following the Mississippi River Basin. They are also native to peninsular Florida. They have also been widely introduced to Atlantic-draining rivers east of the Appalachians and Pacific-draining rivers west of the Rockies, giving them a continent-spanning range. Although they are officially considered introduced to this region, it has been suggested that they may also be native to the Atlantic-draining rivers from the Susquehanna south to the Neuse. Its range in southern Canada includes the Great Lakes (excluding Lake Superior) and parts of the Quebec, Ontario, and Manitoba provinces.
They have also been introduced into some waters of the Czech Republic and Romania, as well as parts of Malaysia and Indonesia.
This species thrives in rivers, reservoirs, lakes, and ponds. Channel catfish are cavity nesters, which means that they lay their eggs in crevices, hollows, or debris to protect them from swift currents.
Characteristics
thumb|At [[Gavins Point National Fish Hatchery]]
Channel catfish have a well developed sense of smell and taste. Their nostril pits (nares) contain sense organs with high concentrations of olfactory receptors. In channel catfish, these organs are sensitive enough to detect several amino acids at about one part per 100 million in water. Also, the channel catfish has taste buds distributed over the surface of its entire body. These buds are especially concentrated on the four pairs of barbels (whiskers) surrounding the mouth, which have about 25 buds per square millimeter. This combination of strong senses of taste and smell allows the channel catfish to find food in dark, stained, or muddy water with relative ease. They also possess a Weberian apparatus, which amplifies sound waves that would otherwise not be perceptible. There is a misconception that the barbels of channel catfish sting upon contact. The barbels lack such capabilities and cannot sting. However, these catfish do have spines on their pectoral and dorsal fins which may cause injury if the fish is handled improperly. There is a common misconception that being pricked by a catfish spine is dangerous: it is no more dangerous than a sting from a mosquito.
Length and weight
350px|right | thumb | Weight vs. length for channel catfish, where b = 3.2293 and <math>L_1 = 45.23</math> cm
An average adult channel catfish measures at least 12 inches (30 centimeters) long, and weighs between 2 and 4 pounds. The largest specimen on record weighed 58 pounds and was caught in 1964 by an angler in South Carolina.
As channel catfish grow longer, their weight increases. The relationship between length and weight is not linear. The relationship between length (L, in cm) and weight (W, in kg) for nearly all species of fish can be expressed by an equation of the form:
:<math>W = (L/L_1)^b\!\,</math>
Invariably, b is close to 3.0 for all species, <math>L_1</math> is the length of a typical fish weighing 1 kg. For channel catfish, b = 3.2293, somewhat higher than for many common species, and <math>L_1 = 45.23</math> cm. Like other catfish, channel catfish feed through suction by opening their mouths quickly to create a vacuum into which water and food rapidly flow. They lack large teeth and, rather than biting and chewing, swallow their food whole.
Diet
Adult channel catfish, over , prey on fishes such as yellow perch and sunfish. The diet of adults consists of snails, clams, crustaceans (such as crayfish), snakes, frogs, small fish, insects, aquatic plants, algae, seeds, grains, nuts, and occasionally even small birds and small mammals. Younger channel catfish are more consistently omnivorous, eating a large variety of plants and animals. Members of the genus Ictalurus, which lives in muddy waters with very bad sight, do not depend solely on visual cues. Instead, they are known to rely heavily on chemotactic cues. Sound production may be another important means of communication among channel catfish and other species living in turbid habitats.
Chemical communication
The North American channel catfish is an ostariophysan, or a bony fish living in freshwater habitats. Stridulation consists of the clicking or grinding of bony parts on the fish's pectoral fins and pectoral girdle, and drumming consists of the contraction of specialized sonic muscles with subsequent reverberation through the swim bladder. These noises are distinguished by distinct pulses produced when the ridges on the spine's base interact with the rough surface of the girdle's channel.
In many channel catfish, individuals favor one fin or another for stridulatory sound production (in the same way as humans are right-handed or left-handed). The first ray of the channel catfish pectoral fin is a bilaterally symmetrical spinous structure that is minimally important for movement; however, it can be locked as a defensive adaptation or used as a means for sound production. The hearing ability of the channel catfish is enhanced by the presence of the swim bladder. It is the main structure that reverberates the echo from other individuals' sounds, as well as from sonar devices. In most catfish, a drumming sound can be produced for this use, and the incidences of the drumming sounds can reach up to 300 or 400 per second. However, the channel catfish must resort instead to stridulation sounds and pectoral spine display for predator avoidance. In addition to communication towards predators, stridulation can be seen as a possible alarm signal to other catfish, in the sense of warning nearby individuals that a predator is near. Results from comparative genomics and transcriptomics analyses and experiments involving channel catfish have supported a role for secretory calcium-binding phosphoproteins (SCPP) in scale formation in teleost fishes. Other studies of genetic diversity, outcrossing, etc. in channel catfish have focused primarily on inbred lines and farm strains relevant to this species' aquaculture. For example, earlier studies have compared the genetic diversity of domestic versus wild populations of channel catfish using AFLPs.
Cultural & economic significance
thumb|right|Chuck the Channel Catfish, 1986 roadside sculpture in [[Selkirk, Manitoba]]
thumb|Global aquaculture production of Channel catfish (Ictalurus punctatus) in thousand tonnes from 1960 to 2022, as reported by the [[Food and Agriculture Organization|FAO]]
The channel catfish is an important food source in the southern United States and is valued for the quality of its meat. In the United States, catfish is the largest aquaculture industry, and channel catfish make up 90% of farm-raised catfish. In 2021, catfish farmers in the United States made $421 million in sales. Most catfish farming in the United States occurs in the southeast: Alabama, Arkansas, Louisiana, and Mississippi produce 94% of American farm-raised catfish, with Mississippi responsible for over 50%.
Fishing
thumb|Channel catfish caught in a stocked lake
Channel catfish are omnivores, and can be caught using a variety of natural and prepared baits, including crickets, nightcrawlers, minnows, shad, freshwater drum, crawfish, frogs, bullheads, sunfish, chicken liver, raw steak, hot dogs, and suckers. Catfish have even been known to take Ivory soap as bait.
When removing the hook from a catfish, anglers should be mindful of the sharp spines on the pectoral and dorsal fins, since they inject venom and may cause injury.