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Blue Catfish (Ictalurus furcatus)
Ecological Risk Screening Summary
U.S. Fish & Wildlife Service, August 2014
Revised, July 2019
Web Version, 1/16/2020
Image: D. Raver, U.S. Fish and Wildlife Service.
1 Native Range and Status in the United States
Native Range
From Fuller and Neilson (2019):
“Native Range: Mississippi River basin from western Pennsylvania to southern South Dakota
and the Platte River, southwestern Nebraska, south to the Gulf of Mexico; tributaries of the gulf
from Mobile Bay basin, Alabama, to the Rio Grande drainage, Texas and New Mexico. Ictalurus
furcatus is endemic to the Mississippi, Missouri, and Ohio River basins of the central and
southern United States and inhabits Gulf Coast streams from Alabama south into Mexico. Also,
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native to the Atlantic Slope of Mexico (Page and Burr 1991) if not distinguished separately from
I. meridionalis (Gilbert 1998). Rarely found in the Mississippi above the confluence with the
Missouri River (Becker 1983). Two historic records from Wisconsin (one from Lake Pepin, and
one from Lansing Iowa) are believed to be misidentifications of Channel Catfish (Becker 1983).
As such, Becker does not consider the species native to Wisconsin.”
From CABI (2019):
“The blue catfish, Ictalurus furcatus, is native to central and southern states of the USA, Mexico
and Guatemala.”
“I. furcatus is native to the major rivers of Mississippi, Missouri, and Ohio basins of central and
southern USA, south into Mexico and northern Guatemala (Glodek, 1980).”
“In Texas, the species is present in all parts of the state but is absent from the northwest (Hubbs
et al., 1991). Warren et al. (2000) listed the following drainage units for distribution of I.
furcatus in the state: Red River (from the mouth upstream to and including the Kiamichi River),
Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay
(including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado
River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to
mouth of Nueces River) and Nueces River. Warren et al. (2000) also reported that the
populations in southern drainages are currently stable.”
Status in the United States
According to Fuller and Neilson (2019), nonindigenous occurrences of Ictalurus furcatus have
been reported in the following states, with range of years and hydrologic units in parentheses:
Alabama (1971-2012; Apalachicola Basin; Lower Chattahoochee; Middle
Chattahoochee-Walter F; Upper Choctawhatchee; Upper Conecuh)
Arizona (1973-2011; Imperial Reservoir; Upper San Pedro)
California (1966-2014; Los Angeles; Lower Sacramento; Middle San Joaquin-Lower
Chowchilla; San Diego; San Joaquin Delta; Santa Ana; Santa Clara; Santa Margarita;
Santa Maria)
Colorado (1952-2009; San Luis; South Platte; Upper Arkansas; Upper Arkansas-John
Martin Reservoir; Upper Arkansas-Lake Meredith)
Delaware (2010-2019; Brandywine-Christina; Nanticoke)
District of Columbia (2010-2010; Middle Potomac-Anacostia-Occoquan)
Florida (1968-2008; Apalachicola; Escambia; Lower Choctawhatchee; Lower Conecuh;
Lower Suwannee; Yellow)
Georgia (1971-2016; Altamaha; Cumberland-St. Simons; Etowah; Hiwassee; Lower
Chattahoochee; Lower Flint; Middle Chattahoochee-Lake Harding; Middle
Chattahoochee-Walter F; Middle Savannah; Satilla; Upper Ocmulgee; Upper Oconee;
Upper Savannah; Upper Tallapoosa)
Idaho (1985-1990; Bear Lake; Brownlee Reservoir; C.J. Strike Reservoir; Lake Walcott;
Upper Snake-Rock)
Iowa (1900-1987; Coon-Yellow)
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Kansas (1980-2003; Denton; Lower Marais Des Cygnes; Lower Republican; Medicine
Lodge; Middle Republican; Neosho Headwaters; Smoky Hill; South Fork Ninnescah;
Upper Cimarron; Upper Marais Des Cygnes; Upper Neosho; Upper South Fork Solomon)
Kentucky (2002-2002; Salt)
Maryland (2010-2015; Lower Potomac; Lower Susquehanna; Middle Potomac-
Anacostia-Occoquan; Monocacy; Patuxent)
Minnesota (1900-2001; Lower St. Croix; Rush-Vermillion; St. Croix)
Nebraska (1980-2011; Lower Platte-Shell; Salt; Upper Republican)
New Jersey (1920-1978; Hackensack-Passaic; Lower Hudson; Mid-Atlantic Region)
New Mexico (1955-2007; Conchas; Upper San Juan)
North Carolina (1975-2018; Albemarle; Black; Cape Fear; Chowan; Contentnea; Lower
Cape Fear; Lower Pee Dee; Lower Roanoke; Lower Tar; Lumber; Meherrin; Middle
Neuse; Northeast Cape Fear; Roanoke Rapids; Upper Cape Fear; Upper Catawba; Upper
Neuse; Upper Pee Dee; Upper Pee Dee; Upper Yadkin; Waccamaw)
North Dakota (1980-1980; Upper Lake Oahe)
Ohio (1975-2013; Licking; Lower Great Miami; Muskingum; Upper Great Miami; Upper
Scioto)
Oklahoma (1947-2007; Arkansas-White-Red Region; Blue-China; Cache; Caney;
Chikaskia; Clear Boggy; Deep Fork; Lake O' The Cherokees; Little; Lower Canadian;
Lower Canadian-Walnut; Lower Cimarron; Lower Cimarron-Skeleton; Lower Neosho;
Lower North Canadian; Lower North Fork Red; Lower Verdigris; Middle North
Canadian; Middle Verdigris; Middle Washita; Muddy Boggy; Poteau; Upper Little; West
Cache)
Oregon (1910-1946; Brownlee Reservoir; Middle Willamette)
South Carolina (1964-2018; Carolina Coastal-Sampit; Congaree; Cooper; Edisto River;
Lake Marion; Lower Pee Dee; Middle Savannah; Salkehatchie; Santee; Seneca;
Waccamaw; Wateree)
South Dakota (19800-1980; Fort Randall Reservoir; Lower Lake Oahe)
Tennessee (1993-1993; Conasauga)
Texas (1965-2018; Atascosa; Austin-Travis Lakes; Bosque; Brady; Buchanan-Lyndon B.
Johnson Lakes; Cedar; Chambers; Cibolo; Colorado Headwaters; Concho; Cowhouse;
Denton; Double Mountain Fork Brazos; East Fork Trinity; Elm Fork Trinity; Hondo;
Hubbard; Jim Ned; Lake Meredith; Lake O'the Pines; Lampasas; Leon; Little; Little
Wichita; Llano; Lower Angelina; Lower Brazos-Little Brazos; Lower Colorado-
Cummins; Lower Frio; Lower Pecos-Red Bluff Reservoir; Lower Prairie Dog Town Fork
Red; Lower Trinity-Kickapoo; Lower Trinity-Tehuacana; Lower West Fork Trinity;
Medina; Middle Brazos-Lake Whitney; Middle Brazos-Millers; Middle Brazos-Palo
Pinto; Middle Colorado; Middle Colorado-Elm; Middle Guadalupe; Middle Neches;
Middle Nueces; Middle Sabine; Navasota; North Bosque; North Concho; North Fork
Double Mountain Fork Brazos; North Llano; Nueces Headwaters; Paint; Pecan Bayou;
Pedernales; Richland; San Gabriel; San Marcos; San Miguel; San Saba; South Concho;
South Llano; Sulphur Headwaters; Tule; Turkey; Upper Angelina; Upper Clear Fork
Brazos; Upper Colorado; Upper Frio; Upper Guadalupe; Upper Neches; Upper North
Fork Red; Upper Nueces; Upper Salt Fork Red; Upper San Antonio; Upper Trinity;
Upper West Fork Trinity; West Nueces; White; Wichita; Yegua)
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Virginia (1974-2016; Albemarle; Appomattox; James; Lower Chesapeake Bay; Lower
James; Middle James-Willis; Middle Potomac-Anacostia-Occoquan; Middle Roanoke;
Pamunkey; Rapidan-Upper Rappahannock; Shenandoah)
Washington (1910-1910; Lower Snake)
Wisconsin (1998-2006; South Fork Flambeau; Upper Fox)
From Fuller and Neilson (2019):
“Not listed as occurring in South Carolina by Loyacano (1975). Not listed as occurring in Idaho
by Simpson and Wallace (1978). Reports of I. furcatus in the New drainage in West Virginia and
Virginia are more likely misidentified I. punctatus (Burkhead et al. 1980).”
“There is considerable doubt about the introduction of this species in the Potomac River near the
turn of the century. Although numerous authors (Bean and Weed 1911; McAtee and Weed
1915; Wiley 1970; Jenkins et al. 1972; Stauffer et al. 1978; Graham 1999) report that the species
was introduced between 1898 and 1905, it appears that statement is based on misidentified I.
punctatus (Burkhead et al. 1980), or if any of those fish actually were I. furcatus, the introduction
failed. Starnes et al. (2011) reported that young I. furcatus were increasing in number in the
lower reaches of the Potomac, and that this species is established in river and the Chesapeake
and Ohio Canal up through the Plummers Island region.”
NatureServe (2013):
“In Missouri, stocking of this species in small impoundments has not resulted in the
establishment of self-sustaining populations (Pflieger 1997).”
“Locally, impoundments have eliminated or reduced some populations. For example, a
population in the White River, Missouri, disappeared after construction of Bull Shoals and Table
Rock reservoirs (Pflieger 1997).”
From CABI (2019):
“This species is ranked in the top five "species of concern" in Virginia and also as a high priority
in Maryland by the US Environmental Protection Agency's Chesapeake Bay Program. It was
further identified as a species for which a risk assessment plan is required (Moser, 2002).”
“It is, however, ranked among the most invasive species in Chesapeake Bay in the United States
(Higgins, 2006).”
“Within the United States, stocking programs and unauthorized introductions have established I.
furcatus populations in reservoirs and rivers of several states, including tributaries of the
Chesapeake Bay in Maryland and Virginia. The species was intentionally introduced to three
major tributaries of Chesapeake Bay watershed and a number of impoundments between 1974
and 1989 for sport fishing, and has since spread into three additional tributaries (Higgins, 2006).”
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“Although I. furcatus were reported as introduced to the Chesapeake Bay region between 1898
and 1905 in the Potomac River, this purported introduction has been attributed to a misidentified
Ictalurus punctatus (Burkhead et al., 1980). From 1974 to 1985, juvenile I. furcatus were
introduced into coastal rivers of Virginia to establish self-sustaining fisheries (Higgins, 2006).”
Means of Introductions in the United States
Ictalurus furcatus has been intentionally stocked outside its native range within the United States
by State fishery managers to achieve fishery management objectives. State fish and wildlife
management agencies are responsible for balancing multiple fish and wildlife management
objectives. The potential for a species to become invasive is now one important consideration
when balancing multiple management objectives and advancing sound, science-based
management of fish and wildlife and their habitat in the public interest.
From Fuller and Neilson (2019):
“Means of Introduction: Intentionally stocked for food and sport. Stocked in the Cape Fear
River, North Carolina, in 1966 (Guire et al. 1984). Introductions in the Choctawhatchee River,
Alabama, were due to flooding of a private lake in 1993 (Mettee et al. 1996). Recent
introductions into the Chattahoochee River in Alabama and Georgia were due to flooding of
catfish farms in Alabama during a storm in March 1990 (Ober, personal communication).
Presumably these fish moved downstream into the Apalachicola in Florida. Sources of
introductions in Escambia and Yellow rivers of Florida are unknown (R. Cailteux, personal
communication).”
“Blue Catfish has been stocked to feed on the introduced Asian clam Corbiucula fluminea.
Although the species may not actually control clam populations, it is hoped that clam biomass
could be converted to fish biomass and create trophy-sized catfish to catch (Dill and Cordone
1997). Blue Catfish are known to consume the invasive Asian clam, Corbicula fluminea, in Lake
Norman (NC Wildlife Resources Commission, pers. comm.), and feed almost exclusively on
Corbicula in the Cape Fear River, North Carolina, (M. Moser, personal communication).”
From CABI (2019):
“Within the United States, stocking programs and unauthorized introductions have established I.
furcatus populations in reservoirs and rivers of several states, including tributaries of the
Chesapeake Bay in Maryland and Virginia. The species was intentionally introduced to three
major tributaries of Chesapeake Bay watershed and a number of impoundments between 1974
and 1989 for sport fishing, and has since spread into three additional tributaries (Higgins, 2006).
According to Guire et al. (1984), the intentional stocking of this species for food and sport
fishery took place in 1966. Introductions in the Choctawhatchee River, Alabama, were due to
flooding of a private lake in 1993 (Mettee et al., 1996). It is assumed that these fish moved
downstream into the Apalachicola in Florida (Fuller and Neilson, 2012). Sources of introductions
in Escambia and Yellow rivers of Florida are unknown (R. Cailteux, personal communication as
stated in Fuller and Neilson, 2012).”
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“Main means of dispersal of I. furcatus is natural dispersal and intentional introductions. It has
been reported that I. furcatus has established secondary populations outside its native range due
to its natural movement and/or intentional introductions. Higgins (2006), using genetic variation
in fish populations, tested the sources of the secondary populations of two primary invasions
within the United States. The tested means of secondary populations are (1) Natural dispersal
(recruits moved from a nearby stocked river through the Chesapeake Bay during periods of
significant freshwater influx), and (2) Intentional introductions (Bubba). It is widely believed
that the I. furcatus range expansion was intentionally facilitated by anglers or commercial
fisherman. Although not inconceivable, Higgins (2006) found that genetic evidence did not
support the Bubba mechanism as the primary mode of expansion and natural dispersal was found
to be the most probable mode underlying the range expansion. Though not tested, he also stated
that it is worth investigating a separate scenario, i.e. escapement from impoundments, as a
number of characteristics of the population genetic and mixed stock analyses suggested that this
could also be a possible mechanism.”
Remarks
From CABI (2019):
“Alterations made to their native riverine habitats, particularly on the peripheries, has seen their
numbers reduced in their native range. Changes to their native range leading to a decline in
abundance may include construction of impoundments, channelization and increases in siltation
(Graham, 1999; Higgins, 2006).”
“I. furcatus most closely resembles the headwater catfish (Ictalurus lupus) and the channel
catfish (Ictalurus punctatus) (Virginia Department of Game and Inland Fisheries, 2012). Juvenile
I. punctatus typically will have spots that are lacking in the juvenile I. furcatus. However, large I.
punctatus and medium-sized I. furcatus can be more difficult to tell apart as they are often
similar in colour and general body shape. I. furcatus can be distinguished from I. lupus and I.
punctatus by having smaller eyes situated more anteriorly; a longer and straighter margin on the
anal fin; a median keel-like crest anterior to the dorsal fin; a crest on the dorsal edge of the
opercle; the sides lacking dark spots; and a higher number of anal rays (I. furcatus usually has
>32; I. puntatus usually has 25-28; I. lupus usually has <25;) (Sublette et al., 1990).”
A previous version of this ERSS was published in 2014. Revisions were done to incorporate new
information and to bring the document in line with current standards.
2 Biology and Ecology
Taxonomic Hierarchy and Taxonomic Standing
From Fricke et al. (2019):
“Current status: Valid as Ictalurus furcatus (Valenciennes 1840).”
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From ITIS (2019):
“Kingdom Animalia
Subkingdom Bilateria
Infrakingdom Deuterostomia
Phylum Chordata
Subphylum Vertebrata
Infraphylum Gnathostomata
Superclass Actinopterygii
Class Teleostei
Superorder Ostariophysi
Order Siluriformes
Family Ictaluridae
Genus Ictalurus
Species Ictalurus furcatus (Valenciennes in Cuvier and Valenciennes,
1840)”
Size, Weight, and Age Range
From Froese and Pauly (2019):
“Max length : 165 cm TL male/unsexed; [Page and Burr 2011]; max. published weight: 68.0 kg
[Frimodt 1995]; max. reported age: 21 years [Hugg 1996]”
From Fuller and Neilson (2019):
“Size: 165 cm (maximum length); 40-50 kg (Graham et al. 1999)”
From CABI (2019):
“It has the ability to grow to a large size, to exceed 165 cm in length and 45 kg in weight and has
a lifespan of around 20 years (Graham, 1999).”
“It is reported that I. furcatus lives at least 14 years (Kelley, 1969 as stated in Hassan-Williams
and Bonner, 2007). Due to its large size, Ross (2001) and Smith (1979) noted that the life span of
I. furcatus is likely to be over 20 years. Some records of lifespan for this fish are from 21 years
to 29 years (Hugg, 1996; Graham, 1999).”
Environment
From Froese and Pauly (2019):
“Freshwater; brackish; demersal; depth range 50 - ? m [Page and Burr 1991].”
From Fuller and Neilson (2019):
“The harsh winters in their native and introduced range region make it likely Blue Catfish can
survive low temperatures. They can be found in the Missouri River near Bismarck, North Dakota
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(Fuller and Neilson 2013). A CLIMATCH analysis included in the USFWS risk assessment for
Blue Catfish found that the climate of the Great Lakes Basin closely matches the climate of their
current range (Australian Bureau of Rural Sciences 2008).This species migrates toward warmer
waters during winter and to cooler waters during summer (Graham 1999). Their preferred
temperature is between 28 and 30°C. In fish farms in Mississippi Delta, 95% survive after
winter with temperatures as low of 5.1°C (Bosworth 2012).”
Climate/Range
From Froese and Pauly (2019):
“Subtropical; 44°N - 25°N, 108°W - 80°W [Page and Burr 2011]”
Distribution Outside the United States
Native
From Fuller and Neilson (2019):
“Native Range: Mississippi River basin from western Pennsylvania to southern South Dakota
and the Platte River, southwestern Nebraska, south to the Gulf of Mexico; tributaries of the gulf
from Mobile Bay basin, Alabama, to the Rio Grande drainage, Texas and New Mexico. Ictalurus
furcatus is endemic to the Mississippi, Missouri, and Ohio River basins of the central and
southern United States and inhabits Gulf Coast streams from Alabama south into Mexico. Also,
native to the Atlantic Slope of Mexico (Page and Burr 1991) if not distinguished separately from
I. meridionalis (Gilbert 1998). Rarely found in the Mississippi above the confluence with the
Missouri River (Becker 1983). Two historic records from Wisconsin (one from Lake Pepin, and
one from Lansing Iowa) are believed to be misidentifications of Channel Catfish (Becker 1983).
As such, Becker does not consider the species native to Wisconsin.”
From CABI (2019):
“The blue catfish, Ictalurus furcatus, is native to central and southern states of the USA, Mexico
and Guatemala.”
“I. furcatus is native to the major rivers of Mississippi, Missouri, and Ohio basins of central and
southern USA, south into Mexico and northern Guatemala (Glodek, 1980).”
“In Texas, the species is present in all parts of the state but is absent from the northwest (Hubbs
et al., 1991). Warren et al. (2000) listed the following drainage units for distribution of I.
furcatus in the state: Red River (from the mouth upstream to and including the Kiamichi River),
Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay
(including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado
River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to
mouth of Nueces River) and Nueces River. Warren et al. (2000) also reported that the
populations in southern drainages are currently stable.”
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Introduced
Froese and Pauly (2019) lists Ictalurus furcatus as introduced from the United States to China.
From CABI (2019):
“I. furcatus has been introduced to China from its native United States for fisheries and
aquaculture purposes. Neither records of its establishment in natural waters in China nor its
spread to other geographical areas from China and its subsequent ecological effects are
reported.”
Means of Introduction Outside the United States
From CABI (2019):
“In China, it has been introduced for aquaculture but is not known as invasive.”
Short Description
CABI (2019):
“Ictalurus has the Greek meaning of "fish cat", and furcatus has the Latin meaning of "forked", a
reference to the species' forked tail fin (Texas Parks and Wildlife, 2012). It has a moderately
robust, elongated body with a deeply forked tail and a rounded head, which has a sub-terminal
mouth (Hubbs et al., 1991; Goldstein and Simon, 1999; Ross, 2001; Virginia Department of
Game and Inland Fisheries, 2012). The lower jaw of the mouth never protrudes beyond the upper
jaw (Graham, 1999). I. furcatus has a bluish-grey colouration on the back, silvery grey sides and
a greyish-white abdomen (Sublette et al., 1990). The breeding male is dark blue in the body
(Moyle, 1976). Blue catfish populations in Rio Grande River in Texas differ from blue catfish in
other areas in that the juvenile and young are very speckled and many adults retain their spots
(Wilcox, 1960).
The deeply forked caudal fin of I. furcatus has no adipose adjoining it and the genital orifices of
the male and female are distinct (Hubbs et al., 1991). In the male, the papilla is more prominent
with a circular opening whereas in the female it is more recessed and the opening is slit-like
(Moyle, 1976). It has 30-36 anal fin rays (Hubbs et al., 1991), 6 dorsal fin rays, 8-10 pectoral fin
rays, 8 pelvic fin rays; and a gill raker count of 14-21 (Ross, 2001).”
Biology
From Froese and Pauly (2019):
“Inhabits deep water of impoundments and main channels and backwaters of medium to large
rivers, over mud, sand and gravel [Page and Burr 1991; Page and Burr 2011]. Stays on the
bottom during the day in deep areas and moves into swifter water at night to feed [NatureServe
2013]. Feeds on small aquatic invertebrates, clams and fishes [Murdy and Musick 2013]. Prefers
clear, strongly flowing water. Deposits eggs in nests under under logs, brush, or riverbank
[NatureServe 2013]. Males build nest often in pools or backwaters [NatureServe 2013].
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Marketed fresh and frozen. Eaten steamed, fried, broiled, microwaved and baked [Frimodt
1995].”
From Fuller and Neilson (2019):
“Ecology: Ictalurus furcatus can tolerate salinities up to 15 ppt (Christmas and Waller 1973,
Dennison et al. 1993, Perry 1968, Ross 2001, Bonvechio et al. 2012). Their survival is 87% in
experimental conditions of dissolved oxygen at 1.41 ppm (Torrans et al. 2012).”
“Blue Catfish can live in a variety of habitats. They inhabit river channels which have higher
flows and harder substrates (i.e., gravel, boulders, rock rip rap), and floodplain lakes which have
lower or no flows and softer substrates (i.e., silt, sand) (Eggleton and Schramm Jr 2004). Blue
Catfish prefer open waters of large reservoirs and main channels, backwaters, and embayments
of large, flowing rivers where water is normally turbid and substrate varies from gravel-sand to
silt-mud (Burr and Warren 1986). Many rivers and reservoirs with I. furcatus populations have
only mud or silt substrate. Blue Catfish prefer deep, swift channels and flowing pools (Jenkins
and Burkhead 1994), and large individuals often are found in tailwaters below dams where
currents are swift and substrates consist of sand, gravel, and rock (Mettee et al. 1996, Graham et
al. 1999).
Blue Catfish are highly omnivorous. In the lower Mississippi River, across all habitats their diets
were composed of 47% fishes (more than 15 identifiable species), 15% molluscs, 12%
chironomids and oligochaetes, 7% detritus/plant matter, 6% decapods, 6% scavenging, and 1%
terrestrial arthropods (Eggleton and Schramm Jr. 2004). Scavenged items were typically fishes
and fish scales, but also included small mammals, birds, and turtles.
Blue Catfish spawns in late spring to early summer at water temperatures of 21 to 25°C (Sublette
et al. 1990) In advance of spawning, Blue Catfish seek protected areas to deposit eggs behind
rocks, root-wads, depressions, undercut stream banks, or other areas where the currents are
minimal (Graham et al. 1999).
Males guard eggs and fry (Graham et al. 1999) which is a strategy associated with animals that
have high colonization success.”
“Reproductive Biology
The spawning behaviour of I. furcatus appears to be similar to that of I. punctatus. However,
most I. furcatus are not sexually mature until they reach about 60 cm in length. Like I. punctatus,
I. furcatus pursues a varied diet, but it tends to eat fish earlier in life. Although invertebrates still
comprise the major portion of the diet, blue catfish as small as 10 cm in length have been known
to consume other fish. Individuals larger than 20 cm eat fish and large invertebrates. I. furcatus
commonly attain weights of 20-40 lbs. and may reach weights well in excess of 100 lbs. It is
reported that fish exceeding 350 lbs. were landed from the Mississippi River during the late
1800s.
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Spawning of I. furcatus occurs in late spring and early summer at water temperatures of 21-250C
(Sublette et al., 1990). However, the spawning season may vary according to geographic
location, in April and May (in Louisiana) or in June (in Illinois) (Jordan and Evermann, 1916;
Pflieger, 1975; Smith, 1979). Spawning takes place in nests constructed by the male in sheltered
areas, often in pools and backwaters (Sublette et al., 1990; Simon, 1999). Although nesting
habits are similar to those of I. punctatus (Pflieger, 1975) no other North American freshwater
fish is known to provide the same level of parental care as I.furcatus. The young of this species
will be guarded by the parents at the nest until the young have hatched (Smith 1979; Higgins,
2006).
Human Uses
From Froese and Pauly (2019):
“Fisheries: commercial; aquaculture: commercial; gamefish: yes; aquarium: public aquariums”
From Fuller and Neilson (2019):
“Blue Catfish has been stocked to feed on the introduced Asian clam Corbiucula fluminea.
Although the species may not actually control clam populations, it is hoped that clam biomass
could be converted to fish biomass and create trophy-sized catfish to catch (Dill and Cordone
1997). Blue Catfish are known to consume the invasive Asian clam, Corbicula fluminea, in Lake
Norman (NC Wildlife Resources Commission, pers. comm.), and feed almost exclusively on
Corbicula in the Cape Fear River, North Carolina, (M. Moser, personal communication).”
From CABI (2019):
“Economic Value
I. furcatus is considered as a highly valued food and recreational fish. It has been introduced to at
least 16 states in the USA outside of its native range and is used to add diversity to fisheries
(Fuller et al., 1999; Graham, 1999). I. furcatus populations in tidal rivers of Virginia and
Maryland support modest commercial fisheries (Schloesser et al., 2011). Commercial landings of
this species from tidal rivers in both states increased from about 9.5–17 tonnes in 2003–2005 to
more than 72.5 tonnes in 2008 (VMRC 2010; A. C. Carpenter, Potomac River Fisheries
Commission, personal communication as stated in Schloesser et al., 2011).
I. furcatus, or its hybrid with the channel catfish (I. punctatus), has also been reared
commercially. However, the majority of commercial production of catfish in the United States is
from I. punctatus (Stickney 1986; Sublette et al., 1990). Graham (1999) noted that the species
lacks popularity with aquaculturists, but hybrids developed with channel catfish are frequently
used in fee-fishing lakes because of their rapid growth and aggressive disposition.
From a purely economic and sports point of view, I. furcatus could be regarded as a beneficial
introduction, but its effects on native fish communities may not have been well studied
(NEMESIS, 2012).
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Social Benefits
I. furcatus populations in Virginia support a nationally recognized trophy fishery which targets
trophy blue catfish at more than 96.5 cm FL or over 13.6 kg (Schloesser et al., 2011).”
Diseases
No OIE-reportable diseases (OIE 2019) were found to be associated with Ictalurus furcatus.
From Froese and Pauly (2019):
“Contracaecum Infestation 3, Parasitic infestations (protozoa, worms, etc.)
Enteric Septicaemia of Catfish, Parasitic infestations (protozoa, worms, etc.)”
Poelen et al. (2014) lists Agamonema vomitor, Tanaorhamphus, Neoechinorhynchus golvani,
Choanoscolex lamothei, Megathylacoides giganteum, Megathylacoides lamothei,
Proteocephalus, Cleidodiscus, Ligictaluridus mirabilis, Goezia nonipapillata, Dichelyne
robusta, Dichelyne mexicanus, Spinitectus marcospinosus, Spinitectus tabascoensis,
Crepidostomum cooperi, Megalogonia ictaluri, Allacanthochasmus varius, Prosthenhystera
obesa, Phyllodistomum lacustri, Polylekithum ictaluri, Neochasmus ictaluri, Posthodiplostomum
minimum, Diplosomum compactum, Genarchella genarchella, Cladocystis, Camallanus
lacustris, Corallobothrium fimbriatum, Gnathostoma binucleatum, Pomphorhynchus,
Crepidostomum, and Spinitectus as parasites of Ictalurus furcatus.
From Griffin et al. (2009):
“Of the species of Henneguya known to infect ictalurid fishes, only Henneguya pellis (Minchew,
1977) has been reported from the blue catfish Ictalurus furcatus.”
Threat to Humans
From Froese and Pauly (2019):
“Harmless”
3 Impacts of Introductions
From Fuller and Neilson (2019):
“Impact of Introduction: Hybridizes with threatened Yaqui catfish I. pricei in Mexico (U.S. Fish
and Wildlife Service 1994).”
From CABI (2019):
“It is, however, ranked among the most invasive species in Chesapeake Bay in the United States
(Higgins, 2006). It has the ability to grow to a large size, to exceed 165 cm in length and 45 kg in
weight and has a lifespan of around 20 years (Graham, 1999). These characters coupled with its
omnivorous feeding strategy, ability to consume a broad prey base and its high abundance have
13
raised concerns over the effects of this large predator on fish communities in Chesapeake Bay
tributaries (Schloesser et al., 2011). Its potential to expand into a wide geographic area also
causes concerns regarding its invasiveness given that it can tolerate a range of habitats from
freshwater to estuarine water (Perry, 1969). Spread of I. furcatus populations is suspected to
have influenced resident fish assemblages. For example, white catfish (Ictalurus catus), a native
species traditionally utilized by commercial fishers, experienced declines after I. furcatus
populations became established in the mid-1990s (Tuckey and Fabrizio, 2010). The pattern of
establishment followed by a lag phase and then rapid dispersal of I. furcatus in Chesapeake Bay
tributaries in the USA is consistent with population dynamics of an invasive species (Sakai et al.,
2001).”
“Its large size, predatory behaviour, ability to easily increase in abundance and occupy both fresh
and saline waters means that this species has a high risk of spread and the potential to negatively
impact native ichthyofauna. As a measure to promote sport fishing, the Virginia Department of
Game and Inland Fisheries and the US Fish and Wildlife Service introduced I. furcatus into 70
impoundments and reservoirs in Virginia and into the James, Rappahannock, and Mattaponi
Rivers until the early 1990s, I. furcatus were recorded only in the river systems where they had
been introduced (Higgins, 2006). Later, secondary breeding populations of I. furcatus have been
recorded in three additional rivers: Pamunkey, upper Potomac, and Piankatank (Edmonds, 2006)
effectively extending their range to all major tributaries in the Virginia portion of Chesapeake
Bay (Higgins, 2006).
Its continued spread is likely to affect native icthyofauna but also cause changes to local habitats,
particularly because of its nest building behaviour (Courtenay and Stauffer, 1984). Furthermore,
alteration of Chesapeake Bay tributaries from historically ‘bottom-up biomass’ controlled
processes to one that is 'top heavy' with predators has been suggested to be a serious
consequence of the introduction and spread of I. furcatus (Garman et al., 1991).”
“Spread of I. furcatus populations is thought to have influenced resident fish populations. A
decline in the abundance of white catfish (Ictalurus catus), a native species with traditional
commercial fisheries value, has been reported after I. furcatus populations became established in
the mid-1990s (Tuckey and Fabrizio, 2010). I. furcatus may represent a relatively new, and
potentially significant, source of mortality for economically and ecologically important estuarine
fishes such as juvenile American shad (Alosa sapidissima), Atlantic menhaden, and river herring
(Alosa spp.) (Chandler, 1998).”
“The large size, predatory habits, and rapid increase in abundance of this species have raised
concerns about its impact on native biota. It is suspected that competition for resources occurs
with native White Catfish (Ictalurus catus), Brown Bullhead (Ictalurus nebulosus), and Yellow
Bullhead (Ictalurusnatalis) (NEMESIS, 2012). […]
Catch statistics have indicated that I. furcatus has adversely affected clupeid (herring-family
fishes) populations in the James and Rappahannock Rivers (Austin 1998, personal
communication as stated in NEMESIS, 2012). In Virginia, I. furcatus has been associated with
declines in anadromous clupeid populations of American shad (Alsoa sapidissima) and blueback
herring (Alsoaaestivalis), possibly compromising major restoration programs, and adding to the
14
documented negative economic and ecological effects of invasive species range expansion
(Ashley and Buff, 1987; MacAvoy et al., 2000). NEMESIS (2012) reported that I. furcatus is
probably an important predator on introduced centrarchids (Sunfishes).”
From Schmitt et al. (2018):
“Blue catfish Ictalurus furcatus were first introduced into the Chesapeake Bay during the 1970s,
and now form dense populations in several tidal rivers. Despite being labeled as a dangerous
invasive, the feeding ecology of this species is largely unknown. We used a stratified random
design to collect stomachs from 16,110 blue catfish in tidal freshwater, oligohaline, and
mesohaline segments of the James, Pamunkey, Mattaponi, and Rappahannock Rivers. Indices of
diet breadth and omnivory reveal that blue catfish are generalist omnivores with some of the
highest diet breadths ever observed in an estuarine fish species, while trophic level calculations
demonstrate that blue catfish are a mesopredator occupying lower trophic levels than previously
claimed. Cumulative prey curves revealed that large numbers of stomachs are necessary to
adequately characterize the diet of blue catfish, thus previous diet descriptions of this species
should be considered with caution. Blue catfish feed primarily on invasive aquatic vegetation and
Asian clams, though the economically-valuable blue crab Callinectes sapidus is also consumed
regularly. While the per capita impact of blue catfish on imperiled native species appears to be
low, this impact could still be substantial due to high population densities.”
From Bonvechio et al. (2019):
“Potential impacts by Blue Catfish on native fish and mussel species are unknown. Omnivorous
feeding habits have been described in the introduced Blue Catfish population of the Altamaha
River (Bonvechio et al. 2011a). Large Blue Catfish can be piscivorous, similar to large Flathead
Catfish; thus, there is some concern over potential effects of Blue Catfish foraging on native fish
species in the Satilla River (Bonvechio et al. 2009, 2011a). […]. Homer and Jennings (2011)
found shifts in the gillnet catch of Ameiurus catus (L.) (White Catfish) to Blue Catfish in Lake
Oconee, GA, and suggested that competition by introduced Blue Catfish and Flathead Catfish
could drive declines in the abundance of native White Catfish. Similarly, White Catfish declines
have also been noted in Virginia tidal rivers after Blue Catfish introduction (Schloesser et al.
2011). White catfish are found in high numbers in the tidal areas of the Satilla River. Similar to
other recently introduced Blue Catfish populations (Bonvechio et al. 2011a), increased detections
suggest establishment in the Satilla River. While Blue Catfish numbers remain low, impacts
would be difficult to detect or minimal. However, previous works suggest that displacement and
or declines of native species, particularly other native catfishes such as the White Catfish, may
be expected.”
15
4 Global Distribution
Figure 1. Known global distribution of Ictalurus furcatus. Map from GBIF Secretariat (2019).
5 Distribution Within the United States
Figure 2. Known distribution of Ictalurus furcatus in the contiguous United States. Map from
Fuller and Neilson (2019).
16
6 Climate Matching
Summary of Climate Matching Analysis
The climate match for Ictalurus furcatus was high for the majority of the United States. Pacific
coastal areas from Washington to central California, as well as eastern California had patches of
low to medium match. New England also had areas of medium match. The Climate 6 score
(Sanders et al. 2018; 16 climate variables; Euclidean distance) for the contiguous United States
was 0.948, high (scores 0.103 and greater are classified as high). All States had high individual
Climate 6 scores.
Figure 3. RAMP (Sanders et al. 2018) source map showing weather stations throughout the
United States and Mexico selected as source locations (red; United States, and Mexico) and non-
source locations (gray) for Ictalurus furcatus climate matching. Source locations from GBIF
Secretariat (2019) and Fuller and Neilson (2019). Selected source locations are within 100 km of
one or more species occurrences, and do not necessarily represent the locations of occurrences
themselves.
17
Figure 4. Map of RAMP (Sanders et al. 2018) climate matches for Ictalurus furcatus in the
contiguous United States based on source locations reported by GBIF Secretariat (2019). Counts
of climate match scores are tabulated on the left. 0 = Lowest match, 10 = Highest match.
The High, Medium, and Low Climate match Categories are based on the following table:
Climate 6: Proportion of
(Sum of Climate Scores 6-10) / (Sum of total Climate Scores)
Climate Match
Category
0.000≤X≤0.005
Low
0.005<X<0.103
Medium
≥0.103
High
7 Certainty of Assessment
The certainty of assessment for Ictalurus furcatus is medium. Information on the biology,
distribution, and history of introductions was readily available. I. furcatus has been established
outside of its native range within the United States. The information on impacts of introduction,
while not mainly from peer-reviewed sources provides a preponderance of evidence supporting
the history of invasiveness classification.
18
8 Risk Assessment
Summary of Risk to the Contiguous United States
Blue Catfish (Ictalurus furcatus) is a freshwater and brackish water catfish native to portions of
the Mississippi River basin, Texas, and Mexico. Stocking, aquaculture, and migration have all
contributed to the spread of this species throughout much of the southern half of the United
States. Impacts such as hybridization with native species, reduction of native fish abundance, and
alteration of local habitats have been reported for this species leading to a high history of
invasiveness. This species has a high climate match within the United States, with all states in
the contiguous United States having individually high climate matches. The overall risk for this
species is high.
Assessment Elements
History of Invasiveness (Sec. 3): High
Climate Match (Sec. 6): High
Certainty of Assessment (Sec. 7): Medium
Remarks/Important additional information: Refer to “Means of Introduction in the
United States” in Section 2 for a caveat on stocking by State fishery managers to achieve
fishery management objectives.
Overall Risk Assessment Category: High
9 References
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19
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