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Blue catfish

Ictalurus furcatus

What do they look like?

Blue catfish are included in a family with bullhead catfishes, and have many similar features as other members of this group, such as their lack of scales, their single dorsal fin followed by an adipose fin just before their tail fin, and their flat anal fin. Their anal fin is long, their tail fin has a deep fork, and their dorsal fin and posterior fins have spines, which help them defend themselves. Blue catfish have eight whiskers (barbels) on their faces. Blue catfish have two whiskers from their nose, two from both corners of their mouth, and four from the chin. Their jaws contain small teeth. Recognized for their large bodies that can weigh up to 100 pounds (45kg), blue catfish can reach two to five feet in length (600 to 1500mm). Their bodies appear bluish-silver and grey dorsally (on their back), silvery-white on their sides, and white ventrally (on their bellies). They look similar to channel catfish; however, unlike channel catfish, blue catfish have no dark blue spots and have a straight edged adipose fin. Both male and female blue catfish look the same. ("Blue catfish", 2012; Jenkins and Burkhead, 1994; "Maryland fish facts", 2014; Murdy, et al., 1997)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    45 (high) kg
    99.12 (high) lb
  • Average mass
    2 kg
    4.41 lb
  • Range length
    600 to 1500 mm
    23.62 to 59.06 in
  • Average length
    700 mm
    27.56 in

Where do they live?

Blue catfish are found in the Mississippi, Missouri, and Ohio river basins and the Gulf of Mexico drainages from Pennsylvania to South Dakota, and south to the Gulf Coast. They were stocked in the James, Rappahannock, and York Rivers, which expanded their range to the Chesapeake Bay area. They have also been added to areas in Alabama, Florida, California, and Mexico. Today, they are found in most rivers in California, Louisiana, and the Atlantic slope regions including the Rio Grande, James, Rappahannock, Mattaponi, York, Potomac, Patuxent, and Nanticoke Rivers. They have also been reported in the Burke and Brittle Lakes and far north in the Chesapeake Bay tributaries. ("Blue catfish - Chesapeake Bay", 2014; "Invasive catfish", 2013; "Ictalurus furcatus", 2013; Schloesser, et al., 2011; "Ictalurus furcatus", 2014)

What kind of habitat do they need?

Blue catfish mostly live on the sandy bottoms of medium to large freshwater channels and pools with well-flowing currents that are deeper than 6 meters. They enjoy living near or in rock piles that give them a place to rest without currents. In the spring, they may go to areas with little or no currents such as backwaters, sloughs, and reservoirs so they can breed and nest. During these times, they seek protected, slightly isolated, and covered areas such as in logs and under rocks. Blue catfish are more migratory than other catfish species and often travel long distances. They also adjust to changes in water temperature and swim to warmer waters during the winter and cooler waters during the summer. Although blue catfish prefer freshwater, they are sometimes found in saltier estuaries. ("Blue catfish - Chesapeake Bay", 2014; "Blue catfish", 2012; Jenkins and Burkhead, 1994; "Maryland fish facts", 2014; Murdy, et al., 1997; "Invasive catfish", 2013; "Ictalurus furcatus", 2013)

  • Range depth
    15 to 0 m
    49.21 to 0.00 ft
  • Average depth
    6 m
    19.69 ft

How do they grow?

After spawning, blue catfish eggs usually hatch in six to ten days depending on water temperature. The best temperatures for egg growth range between 25 to 27 degrees Celsius. Temperatures below 21 degrees Celsius may damage eggs and lead to fungal growth. After hatching, blue catfish stay in a small 'fry' stage until they completely absorb their yolk sacs, this depends on water temperature and usually takes between 3 to 6 days. Although the habits of blue catfish hatchlings are unknown in the wild, in hatcheries they swim in schools for several weeks before dispersing. Blue catfish are ready to breed when they are 4 to 7 years old; at this time, they are usually 35 to 66 cm (14 to 26 in) long and weigh 2.3 kg. Blue catfish grow slowly during their first few years of development and more quickly as they age. Growth rates vary from river to river depending on how crowded the area is and how much food is available. In the James River, they can grow up to 3 pounds in the first 8 years, while in 11 years, they can reach 20 pounds. ("Blue catfish - Chesapeake Bay", 2014; Greenlee, 2011; Jenkins and Burkhead, 1994; "Freshwater catfish in Texas", 2012; Wyatt, et al., 2006)

How do they reproduce?

Both male and female blue catfish are need for reproduction. Blue catfish spawn with only one partner per yearly reproductive cycle. Mating includes many chemical interactions between males and females. Males build nests and attract females using pheromones before they swim together in various patterns. (Holtan, 1998; Jenkins and Burkhead, 1994; "Ictalurus furcatus", 2014)

Blue catfish spawn and breed once a year between April and June depending on their location. Their breeding behavior is similar to other members of the Bullhead family, especially channel catfish. Their reproductive behavior begins when a male creates a nest about 6 to 14 inches in diameter. They use their tails to sweep away debris and their jaws to remove larger objects. Male and female catfish are attracted to each other due to chemical (pheromonal) cues. Catfish often perform courtship swimming patterns and even mild biting in the nest before fertilization. After the courtship, female catfish deposit about 40 eggs at a time, which stick to the nest. For every kilogram of body weight, females lay 4,000 to 8,000 eggs, a process that may take several hours. During egg dispersal, male catfish fertilize the eggs with sperm. Afterward, males chase females away and guard, organize, and sometimes ventilate eggs with their tails. Once the young hatch, they are believed to form schools before becoming independent. Until then, they stay close to their nest, which is guarded by the male. (Holtan, 1998; Jenkins and Burkhead, 1994; "Invasive catfish", 2013; "Freshwater catfish in Texas", 2012)

  • How often does reproduction occur?
    Blue catfish breed once a year.
  • Breeding season
    Breeding and spawning takes three to four months in the spring.
  • Average number of offspring
    10000
  • Range time to hatching
    3 to 6 days
  • Average time to hatching
    5 days
  • Range time to independence
    1 to 3 weeks
  • Range age at sexual or reproductive maturity (female)
    4 to 7 years
  • Average age at sexual or reproductive maturity (female)
    5 years
  • Range age at sexual or reproductive maturity (male)
    4 to 7 years
  • Average age at sexual or reproductive maturity (male)
    5 years

Although the male is the primary caretaker, both male and female blue catfish care for their young. They seek low current areas with protective structures to better secure their eggs and rear their young. In addition, they seek sturdy and stable surfaces to which their sticky eggs can properly adhere. Once eggs are fertilized, male catfish force females away from the nest to organize and protect the eggs. Males stay within the nest after eggs hatch to guard and direct the young, leaving only when the young completely absorb their yolk sacs. ("Blue catfish - Chesapeake Bay", 2014; Holtan, 1998; "Freshwater catfish in Texas", 2012)

  • Parental Investment
  • male parental care
  • pre-hatching/birth
    • protecting
      • male
  • pre-weaning/fledging
    • protecting
      • male
  • pre-independence
    • protecting
      • male

How long do they live?

Blue catfish usually live 9 to 10 years, but they can live up to twenty years. The oldest known blue catfish was found in Rappahannock River in Virginia and lived to be 25 years old. Their life expectancy can range from river to river, with rivers in Virginia being better suited at producing older and larger catfish. In Maryland, a survey found blue catfish between the ages of 3 to 14 years; although most were between 5 to 7 years old. Males protecting their young help them to survive to maturity and avoid being eaten. During their early life, when they are smaller in size, they are hunted by other fish such as flathead catfish and even their own species. However, as they age, they become larger than other fish, resulting in less predation. ("Blue catfish", 2012; Greenlee, 2011; Murdy, et al., 1997; "Ictalurus furcatus", 2014)

  • Range lifespan
    Status: wild
    25 (high) hours
  • Typical lifespan
    Status: wild
    3 to 14 hours
  • Average lifespan
    Status: wild
    6 hours

How do they behave?

Blue catfish usually rest during the day near the bottom of deep waters. During the night, they swim to faster flowing waters to find food. Blue catfish also migrate and adjust to temperature changes by swimming to warmer waters during the winter and cooler waters during the summer. They often travel upstream during the breeding seasons and move back downstream after the mating season. Catfish species may bite, slam into each other, or swim quickly to show a clear pecking order. ("Blue catfish - Chesapeake Bay", 2014; "Blue catfish", 2012; Greenlee, 2011; Holtan, 1998; Jenkins and Burkhead, 1994; "Ictalurus furcatus", 2013)

Home Range

Unlike flathead catfish, blue catfish do not show territorial behavior for a home range. (Holtan, 1998)

How do they communicate with each other?

Blue catfish communicate with their sensory organs and by releasing chemical pheromones. This communication system is developed enough to have social systems with pecking orders. Hormonal pheromones are very important for reproduction in this species. In the wild, blue catfish rarely mate to form hybrids with other catfish species. This is most likely because each catfish species releases their own type of pheromones. Blue catfish have the ability to taste their surroundings using tissues on their whiskers and certain areas on their skin, this helps them search for food. Instead of relying on their eyesight, they use their whiskers and sense of smell to identify their surroundings. (Broach and Phelps, 2011; "Maryland fish facts", 2014)

What do they eat?

As they grow, blue catfish eat different things, from small invertebrates to a larger variety of fish, worms, clams, small crustaceans, mussels, crabs, insects and even frogs, as they age. Blue catfish eat what they can find and use the sensory tissues on their whiskers and skin to find food. These taste buds allow blue catfish to taste the surrounding environment before they actually eat anything. Young are very small and are easily eaten by other fish, so they feed at night at low depths near cover on zooplankton and aquatic insects. As they grow, their diet expands to include a variety of smaller fish, even their own species. Mollusks have also been found in catfish stomachs, including Asiatic clams. ("Blue catfish - Chesapeake Bay", 2014; Greenlee, 2011; Jenkins and Burkhead, 1994)

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

What eats them and how do they avoid being eaten?

Sea and shorebirds, such as double-crested cormorants, willets, brown pelicans, and osprey, hunt small fish, including blue catfish. In fact, catfish are actually preferred by bald eagles over other fish species. To avoid predators, blue catfish defend themselves with barbs on their dorsal and pectoral fins. The spines have glands at their base that can release toxins and make their way into predators’ wounds and cause sharp pain. ("Blue catfish - Chesapeake Bay", 2014; "Blue catfish", 2012; Jenkins and Burkhead, 1994)

What roles do they have in the ecosystem?

Blue catfish can be predators and prey. They feed on many other fish, which limits the growth of these species. Blue catfish are an excellent food source for predatory birds in the Chesapeake area. They are also eaten by otters and other fish like flathead catfish. As adults, blue catfish may be eaten by humans and birds. Since blue catfish often grow to be very large and eat whatever they can find, they can have a negative impact on other fish communities. Their diets sometimes include endangered fish like shads and herrings, which causes their populations to become even smaller. Blue catfish were introduced to several rivers, but have been able to spread as they do not seem to mind saltier waters, as scientists originally thought. Large populations of blue catfish have reduced the populations of white catfish in Virginia and Maryland. Blue catfish can become infected with various bacteria, which may cause symptoms such as ulcers, frayed fins, white spots around their mouths, fins, and scales, white lesions on their backs and sides, and hemorrhages under their bodies and around their mouths. (Bonvechio, et al., 2012; Jenkins and Burkhead, 1994; Schloesser, et al., 2011; "Ictalurus furcatus", 2014; Wyatt, et al., 2006)

Do they cause problems?

The population growth and dominance of blue catfish has caused the populations of other fish to decline, including white catfish, shads, and herrings. Because the populations of these fish have declined so quickly, blue catfish have gained recognition for damaging their own ecosystem. (Schloesser, et al., 2011)

  • Ways that these animals might be a problem for humans
  • injures humans
    • bites or stings

How do they interact with us?

Blue catfish populations are popular for recreational and commercial fishing. In the James River, blue catfish can grow to large sizes, so recreational fishers often travel to Virginia and the surrounding commonwealths in hopes of catching them. This popularity has lead to a profitable business in guided fishing tours. Their abundance and firm tasty meat make them a source of profit for several inland fisheries. Blue catfish account for one third of the total recreational fishing efforts in Virginia. Likewise, commercial catches of blue catfish in Virginia have increased from about 25,000 pounds in the early 2000s, to well over 1.5 million pounds in 2011. Not only are blue catfish used as sport fishes, they are also an important food source for more than sixteen states. ("Blue catfish - Chesapeake Bay", 2014; Greenlee, 2011; Schloesser, et al., 2011)

Are they endangered?

Populations of blue catfish can sometimes be threatened by reservoirs caused by dams, such as Bull Shoals and Table Rock reservoirs in the White River in Missouri. However, blue catfish have stable birth, death, and growth rates, with populations that are considered to be of least concern overall. This species is neither threatened nor endangered. ("Ictalurus furcatus", 2013)

Contributors

Yama Barekzi (author), Bridgewater College, Maria Hawkins (author), Bridgewater College, Jacob Sheets (author), Bridgewater College, Tamara Johnstone-Yellin (editor), Bridgewater College, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

References

Blue Ocean Institute. 2014. "Blue catfish - Chesapeake Bay" (On-line). Accessed April 20, 2014 at http://blueocean.org/documents/2013/03/blue-catfish-chesapeake-bay-full-species-report.pdf.

Chesapeake Bay Program. 2012. "Blue catfish" (On-line). Chesapeake Bay Program. Accessed April 20, 2014 at http://www.chesapeakebay.net/fieldguide/critter/blue_catfish.

Texas Parks and Wildlife. 2012. "Freshwater catfish in Texas" (On-line). Accessed April 20, 2014 at https://www.tpwd.state.tx.us/publications/pwdpubs/media/pwd_br_t3200_0236.pdf.

NatureServe. 2013. "Ictalurus furcatus" (On-line). Accessed April 20, 2014 at http://www.iucnredlist.org/details/202679/0.

Smithsonian Environmental Research Center. 2014. "Ictalurus furcatus" (On-line). National Exotic Marine and Estuarine Species Information System. Accessed April 20, 2014 at http://invasions.si.edu/nemesis/CH-IMP.jsp?Species_name=Ictalurus+furcatus.

National Oceanic and Atmospheric Administration. 2013. "Invasive catfish" (On-line). National Oceanic and Atmospheric Administration. Accessed April 20, 2014 at http://chesapeakebay.noaa.gov/fish-facts/invasive-catfish.

Maryland Department of Natural Resources. 2014. "Maryland fish facts" (On-line). Accessed April 20, 2014 at http://dnr.wi.gov/topic/fishing/documents/species/catfish.pdf.

Bonvechio, T., B. Bowen, J. Mitchell, J. Bythwood. 2012. Non-indigenous range expansion of the blue catfish (Ictalurus furcatus) in the Satilla River, Georgia. Southeastern Naturalist, 11/2: 349-359.

Broach, J., R. Phelps. 2011. Response of male blue catfish, Ictalurus furcatus, and male channel catfish, Ictalurus punctatus, to female channel catfish given pheromonal steroids or prostaglandin. Journal of the World Aquaculture Society, 42: 376–387.

Greenlee, B. 2011. "Tidal river blue catfish" (On-line). Accessed April 20, 2014 at http://www.dgif.virginia.gov/fishing/conditions/tidal-river-blue-catfish-report.pdf.

Holtan, P. 1998. "Catfish" (On-line). Accessed April 20, 2014 at http://dnr.wi.gov/topic/fishing/documents/species/catfish.pdf.

Jenkins, R., N. Burkhead. 1994. Freshwater Fishes of Virginia. Bethesda, Maryland: American Fisheries Society.

Murdy, E., R. Birdsong, J. Musick. 1997. Fishes of the Chesapeake Bay. Washington, D.C: Smithsonian Institution Press.

Schloesser, R., M. Fabrizio, R. Latour, G. Garman, B. Greenlee, M. Groves, J. Gartland. 2011. Ecological Role of Blue Catfish in Chesapeake Bay Communities and Implications for Management. American Fisheries Society Symposium, 77: 369–382.

Wyatt, T., J. Martinez, R. Sparrow, A. Barkoh. 2006. Guidelines for the culture of blue and channel catfish. Texas: Inland Fisheries Division.

 
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Barekzi, Y.; M. Hawkins and J. Sheets 2014. "Ictalurus furcatus" (On-line), Animal Diversity Web. Accessed December 11, 2017 at http://www.biokids.umich.edu/accounts/Ictalurus_furcatus/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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