Pylodictis olivaris
(Rafinesque, 1818)
Common Name:
Flathead Catfish
Synonyms and Other Names:
mudfish
Identification:
Wide, flat head - more so than native catfishes. Yellow to purple-brown dorsal coloration and pale white to yellow belly. Projecting lower jaw, pale tips on tail fin, short anal fin. Becker (1983); Page and Burr (1991); Etnier and Starnes (1993); Jenkins and Burkhead (1994).Projecting lower jaw, pale tips on tail fin, short anal fin. Becker (1983); Page and Burr (1991); Etnier and Starnes (1993); Jenkins and Burkhead (1994).
Size:
155 cm (Page and Burr 1991)
Native Range:
Mississippi River basin from western Pennsylvania to White-Little Missouri River system, North Dakota, and south to Louisiana; Gulf Slope from Mobile Bay drainage, Georgia and Alabama, to Mexico (Page and Burr 1991).Mississippi River basin from western Pennsylvania to White-Little Missouri River system, North Dakota, and south to Louisiana; Gulf Slope from Mobile Bay drainage, Georgia and Alabama, to Mexico (Page and Burr 1991).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Pylodictis olivaris are found here.
Full list of USGS occurrences
Table last updated 4/18/2024
† Populations may not be currently present.
Ecology:
Pylodictis olivaris is found in large rivers, streams, and lakes, usually over hard bottoms. They prefer deep, sluggish pools, with logs and other submerged debris that can be used as cover. Young P. olivaris live in rocky or sandy runs in the river and in riffles, often under stones on riffles (Hubbs et al. 2004; Page and Burr 2011). This species lives in shallower (<3 m) waters in summer/at night and migrates to deeper waters (> 4m) in the day/winter (Daugherty and Sutton 2005). This species benefits from turbid waters as they are a non-sight feeding predator (Ward and Vaage 2019). Unlike other catfish, Flathead Catfish feed on only live prey. Adult Flathead Catfish are piscivorous ambush predators (Eggleton and Schramm 2004). This species has a diverse diet, feeding on macroinvertebrates and fish, including shads, centrarchids, bass, and crayfish (Schmitt et al. 2019; Montague and Shoup 2021).
Age at sexual maturity appears to be regionally dependent, ranging from 3–5 years for males and 3–7 years for females. Spawning occurs once in late spring to early summer when water temperatures reach 19 to 24 degrees Celsius. One or both parents excavate a nest that is usually made in a natural cavity or near a large submerged object (Jackson 1999). Females lay a mass of up to 100,000 adhesive eggs (Jackson 1999), or 1,637 to 5,025 eggs/kg (Gima 2009). Males guard the nest and agitate the eggs to keep them clean and aerated. The young remain in a school near the nest for several days after hatching, but soon disperse. Flathead Catfish can live up to 28 years (Jackson 1999).
Means of Introduction:
The Flathead Catfish has been intentionally stocked in most cases. In Idaho, however, flatheads were accidentally stocked instead of blue catfish (Simpson and Wallace 1978). Populations in the Apalachicola River, Florida, probably spread from introductions upstream in the Flint River, Georgia. It is believed that flatheads were stocked by anglers circa 1950 in the vicinity of Potato Creek in Upson County, Georgia, with stock from the Tennessee drainage (Quinn 1988). They were recorded in the Flint River below the Warwick Dam at Lake Blackshear in the early 1960s, and at Albany in the early 1970s (Quinn 1988). The species was apparently first stocked in the Cape Fear River in 1966 when 11 sexually mature fish were released near Fayetteville, North Carolina, by North Carolina Wildlife Resources Commission biologists (Guire et al. 1984; Ashley and Buff 1986). Flatheads were stocked in Atlantic drainages (Savannah and Altamaha) in Georgia in the 1970s (Bart et al. 1994; C. Jennings, personal communication). According to Bart et al. (1994), at least some of these were the result of stocking by Georgia Department of Natural Resource personnel. The first known reports of this fish in California were recorded catches made in the lower Colorado River near Yuma in 1966 (Dill and Cordone 1997). The Colorado River populations in California and Arizona resulted, at least in part, from a stocking of about 600 Flathead Catfish above Imperial Dam made by the Arizona Game and Fish Department in 1962 (Dill and Cordone 1997). According to Dill and Cordone (1997), the believed route of the Flathead Catfish was downstream to Imperial Dam and subsequently into the All American Canal system to the Imperial Valley. Minckley (1973) reported that the species was introduced prior to 1950 into the Gila River system, a tributary of the Colorado River; however, Dill and Cordone (1997) indicated that the Flathead Catfish was not taken in the lower Colorado River basin until after 1962. A single fish was taken 20 November 1995 in Arizona from the upper San Pedro River, about 32 kilometers from the Mexican border (S. Stefferud, personal communication). It is not known how the species gained access to the upper reach of this river. In Wisconsin, flatheads probably entered the Wolf and Fox drainages via the canal at Portage (Becker 1983). The Ochlockonee River introduction in Florida and Georgia was probably due to illegal stocking by anglers with fish from the nearby Apalachicola River, where the fish had also been introduced. The flathead's presence in eastern Pennsylvania is most likely due to stock contamination of channel catfish shipments (M. Kaufman, personal communication).
Status:
Occurs in all U.S. states except Alaska, Hawaii, Montana, Utah and the New England states (Montague and Shoup 2021). The Flathead Catfish has become established in most waters where introduced. For instance, it is widespread and reproducing in the lower Colorado River basin (Dill and Cordone 1997). As of about 1980, the Cape Fear River population had expanded from the site of its initial release near Fayetteville, North Carolina, and was found to inhabit a 201-kilometer stretch of the river (Guire et al. 1984). In samples taken by Guire et al. (1984) from the Cape Fear River, flathead accounted for 10.52% of total fish numbers and 64.7% of total fish weight. Establishment in Oregon is uncertain (Bond 1994). The species does not appear to have survived to reproduce in Wyoming (Hubert 1994). It has been reported from the San Pedro River, Arizona, and from the Suwannee River, Florida. Established in Blue Marsh Reservoir and the Schuylkill River in Pennsylvania; reported in Springton Reservoir, Pennsylvania. Great Lakes: Reproducing and overwintering in Lakes Erie, Huron, and Michigan.
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
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Current research on the environmental impact of Pylodictis olivaris in the Great Lakes is inadequate to support proper assessment. Potential:
The following environmental impacts are for water bodies outside of the Great Lakes region. While undocumented, Flathead Catfish populations may have similar impacts in the Great Lakes.
Flathead Catfish carries a novel species of myxozoan (Henneguya laseeae n. Sp.) and flatworm (Ligictaluridus michaelalicea n. Sp) in the Upper Mississippi River (Leis et al. 2017, 2018).
Many feeding studies have found that Flathead Catfish prey heavily on Sunfish Lepomis spp. (e.g., Quinn 1988; Lucchesi et al. 2017). One study found that they reduced the number of Common Carp (Cyprinus carpio) and Bullheads (Ameiurus spp.) (Quinn 1988). However, the introduced population in the Flint River system was found to prey largely on crayfish, and that young-of-the-year Flatheads fed on Darters (Etheostoma spp.), Clupeids, Catostomids, Ictalurids (including other Flatheads), and Centrarchids were also consumed (Quinn 1988). According to Quinn (1988), introduced Flatheads in the Flint River rely more on crayfish than any other Catfish population yet described. A severe decline in native fish species, particularly native Bullhead species, was observed in the Cape Fear River within 15 years of the first Flathead Catfish introduction (Guire et al. 1984; Jenkins and Burkhead 1994). Feeding studies conducted in the Cape Fear River showed that flatheads consume mainly Bullheads, Catfishes, Shad, and Sunfishes (Guire et al. 1984; Ashley and Buff 1986). In 1979, Flatheads in the Cape Fear River fed primarily on Bullheads. However, by 1986, Bullhead populations had declined and Flathead Catfish had switched to preying on Shad (Ashley and Buff 1986). Furthermore, in the upper Gila River, New Mexico, Flathead Catfish had high consumptive demand on native fishes and sometimes exceeded native fish productivity rates (Hedden et al. 2016).
Flathead Catfish, along with other nonnative piscivorous fishes, have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Hughes and Herlihy 2012). Flathead catfish also may be responsible for declines in other native species in the Altamaha drainage (C. Jennings, personal communication). In the Ocmulgee River, Georgia, abundances of Silver Redhorse (Moxostoma anisurum), Robust Redhorse (M. robustum), Snail Bullhead (Ameiurus brunneus), Flat Bullhead (A. platycephalus), and Redbreast Sunfish, were negatively correlated with Flathead Catfish occurrence and abundance (Bart et al. 1994). This correlation may be due to direct predation. Several authors have reported Suckers and Catfish as common prey items of Flatheads (Minckley and Deacon 1959; Davis 1985). The Snail Bullhead and Flat Bullhead appear to be most affected by the presence of Flathead Catfish in the Ocmulgee drainage (Bart et al. 1994).
Flatheads may be contributing to the decline of the federally threatened Gulf Sturgeon (Acipenser oxyrinchus desotoi) by consuming the young benthic fish in the Apalachicola River (J. Williams, personal communication). The Flathead Catfish is thought to be contributing to the decline of the Razorback Sucker (Xyrauchen texanus). For instance, Marsh and Brooks (1989) found that intensive predation by Flathead Catfish and Channel Catfish (Ictalurus punctatus) on juvenile Razorback Suckers is likely to prevent hatchery transplants of this southwestern endangered Sucker from becoming re-established in portions of its natural range. If the Flathead Catfish becomes established in the San Pedro River, it could mean a major loss for recovery of several species (Stefferud, personal communication). While uncommon, Flathead Catfish have been recorded to prey on Pallid Sturgeon (Scaphirhynchus albus) (Steffensen et al. 2015). Predatory impacts of Flathead Catfish could have significant per capita effects on native populations of American Shad (Alosa sapidissima), Blueback Herring (A. aestivalis), and Alewife (A. pseudoharengus) in subestuaries of Chesapeake Bay, Virginia (Schmitt et al. 2019).
There is little or no evidence to support that Pylodictis olivaris has significant socio-economic impacts in the Great Lakes.
Realized:
Flathead Catfish have long sharp spines on the dorsal and pectoral fins. Sharp spines of smaller specimens are very sharp and may cause injury. Puncture wounds from the spines may lead to irritation and secondary infections (Kaar et al. 2014).
Pylodictis olivaris has a high beneficial impact in the Great Lakes.
Realized:
North American catfishes, including Flathead Catfish, are commercially and recreationally valuable (Quinn 2011) and are fished in Illinois and Indiana and throughout their native range (Moody-Carpenter et al. 2017; Winders and McMullen 2021). Flathead Catfish is highly regarded as a food fish in some portions of the Great Lakes region when taken from clean water. This species may have significant positive impacts for tourism (Page and Burr 2011).
Potential:
Flathead Catfish consume Common Carp and may act as a biocontrol agent (Quinn 1988). However, Flathead Catfish had limited to no success at reducing Common Carp abundances in small impoundments in Missouri (Michaletz 2020).
Management:
Regulations (pertaining to the Great Lakes region)
In Canada, the use or possession of fish as live bait in any province other than from which it was taken is prohibited (SOR/93-55). It is illegal to bring any live fish into Ontario for use as bait (SOR/2007-237). This species is listed as invasive in Pennsylvania, however, no specific regulations are defined. Control
Biological
There are no known biological control methods for this species.
Physical
Bonvechio et al. (2011) determined that consistent electrofishing removal of Flathead Catfish could keep populations at low levels of biomass. Intense hand fishing for trophy Flathead Catfish was hypothesized to cause populations to become unsustainable (Bodine et al. 2016). However, a 4 year study revealed hand fishing had insignificant impacts on long term Flathead abundance (Bodine et al. 2021).
Chemical
There are no known chemical control methods specific to this species. General piscicides (e.g., rotenone) may be effective, but significant non-target mortality is expected.
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods.
Remarks:
The Flathead Catfish became the dominant predator in the Cape Fear drainage of North Carolina within 15 years of the introduction (Guire et al. 1984). The species may actually be native to the upper Tennessee drainage in North Carolina (Jenkins and Starnes, personal communication). In their book on Alabama fishes, Mettee et al. (1996) presented conflicting information regarding native versus introduced ranges. These researchers stated, in the species account, that Pylodictis olivaris is introduced to the Conecuh and Escatawpa river systems, but they listed the species as "native" in their summary table. Starnes et al. (2011) suggest that although the Potomac River population is highly localized, favorable habitat in the Plummers Island area could allow it to expand further upstream.
Flathead Catfish was previously suggested as native to the lower Great Lakes (Underhill 1986; Bailey et al. 2004); however, Fuller and Whelan (2018) provided historical evidence for its absence from the basin. University of Michigan voucher specimens are in Bailey et al. (2004) for two tributaries in southern Michigan. A single specimen was caught in the Canadian waters of western Lake Erie in 1978 by a commercial fisherman. This specimen was deposited in the Royal Ontario Museum collection (Crossman and Leach 1979). Despite the fact that Wydoski and Whitney (2003) say Flathead Catfish were in the lower Snake and Columbia rivers by the mid 1970s, neither the regional fishery biologist for that area, nor the warmwater fisheries manager for the state have ever seen or heard of one in the state (Chris Donnelly and Bruce Bolding, Washington Department of Fish and Wildlife, personal communication 1/6/2016, 1/7/2016). Although there is a supposed Washington State Record fish (22.8 lbs from the Snake River in 1981 (WDFW 2021), Bolding believes this was a misidentified Channel Catfish.
References
(click for full reference list)
Author:
Fuller, P., M. Neilson, R. Sturtevant, and A. Bartos
Contributing Agencies:
Revision Date:
9/30/2022
Peer Review Date:
3/24/2022
Citation for this information:
Fuller, P., M. Neilson, R. Sturtevant, and A. Bartos, 2024, Pylodictis olivaris (Rafinesque, 1818): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=750&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 9/30/2022, Peer Review Date: 3/24/2022, Access Date: 4/19/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.