Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Ameiurus nebulosus
(brown bullhead)

Toolbox

Datasheet

Ameiurus nebulosus (brown bullhead)

Summary

  • Last modified
  • 06 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Natural Enemy
  • Host Animal
  • Preferred Scientific Name
  • Ameiurus nebulosus
  • Preferred Common Name
  • brown bullhead
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Chordata
  •       Subphylum: Vertebrata
  •         Class: Actinopterygii
  • Summary of Invasiveness
  • A. nebulosus is a fish of the Ictaluridae family, commonly known as a brown bullhead. It has been introduced outside of its native range in North America to other areas of North America, Europe, Asia and Pacific...

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report

Pictures

Top of page
PictureTitleCaptionCopyright
Ameiurus nebulosus (brown bullhead); artwork of adult fish.
TitleArtwork of adult fish
CaptionAmeiurus nebulosus (brown bullhead); artwork of adult fish.
CopyrightReleased into the Public Domain by the U.S. Fish & Wildlife Service/National Digital Library - Original artwork by Duane Raver Jr.
Ameiurus nebulosus (brown bullhead); artwork of adult fish.
Artwork of adult fishAmeiurus nebulosus (brown bullhead); artwork of adult fish.Released into the Public Domain by the U.S. Fish & Wildlife Service/National Digital Library - Original artwork by Duane Raver Jr.

Identity

Top of page

Preferred Scientific Name

  • Ameiurus nebulosus (Lesueur, 1819)

Preferred Common Name

  • brown bullhead

Other Scientific Names

  • Ictalurus nebulosus (Lesueur, 1819)

International Common Names

  • French: barbotte brune

Local Common Names

  • : bullhead, mudcat, hornpout, catfish, common bullhead, horned pout
  • France: poisson chat

Summary of Invasiveness

Top of page

A. nebulosus is a fish of the Ictaluridae family, commonly known as a brown bullhead. It has been introduced outside of its native range in North America to other areas of North America, Europe, Asia and Pacific islands (i.e. New Zealand, Hawaii). It was likely spread primarily for recreational angling opportunities. Its spread has been undoubtedly facilitated by its ability to survive low oxygen concentrations for prolonged periods (Scott and Crossman, 1973). Its establishment, once introduced, was likely assisted by its generalist, omnivore diet with feeding aided, even in turbid waters, by its chin barbels (Scott and Crossman, 1973). This diet results in predation on a wide variety of native invertebrates, small vertebrates and fish eggs. Conversely, its stout shape and strong dorsal and pectoral fin spines would minimize predation by native predators. Its parental care of eggs and young would also reduce mortality in the young (Scott and Crossman, 1973). The species is recognized within the Global Invasive Species Database (ISSG, 2009).

 

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Chordata
  •             Subphylum: Vertebrata
  •                 Class: Actinopterygii
  •                     Order: Siluriformes
  •                         Family: Ictaluridae
  •                             Genus: Ameiurus
  •                                 Species: Ameiurus nebulosus

Notes on Taxonomy and Nomenclature

Top of page

Within its native range, two subspecies have been identified, Ameiurus nebulous nebulosus, north of a line between Viriginia and North Dakota, and Ameiurus nebulosus marmoratus to the south (Hubbs and Lagler, 1957). Although initially of the Ictalurus genus, Robins et al. (1980) concluded that Ameiurus was valid and was subsequently recommended by Bailey and Robins (1988).

Description

Top of page

A. nebulosus was described thoroughly by Scott and Crossman (1973) using specimens sampled from Ontario and New Brunswick, Canada: “The species is a moderate-sized catfish with adult total lengths between 203-356 mm. Its greatest body depth occurs at the origin of the dorsal fin, typically 17.7-26.3% of total length. The caudal peduncle (tail fin) is moderately deep (depth 8.1-9.9% of total body length) with a straight or slightly rounded posterior edge. The head is massive and somewhat lengthy, usually 22.6-26.3% of total body length, and quite wide throughout. Its eyes are small, with diameter 10.0-18.7% of head length, round, and protruding. Lips are fleshy, but not prominent, with one pair of long flattened maxillary barbels, which are the longest of four pairs of barbels. Its gill rakers are moderately long and pointed. Fins are as follows: 1 dorsal, ahead of midpoint of body, which is soft-rayed but with a strong leading spine. Pectoral fins are high, broad, rounded, with anterior heavy spine with numerous barbs. Spines in dorsal and pectoral fins can be locked in erect position, presumably as a predation deterrence strategy. The adipose fin is small; pelvic fins inconspicuous; and, anal fin long and slender. The skin lacks scales throughout but is complete with taste glands. Its lateral line is complete throughout the midpoint of the body. The dorsal surface of the head and body may be yellow-brown, olive or grey. Sides are often mottled with vague brown blotches. The underside anterior of pelvic fins may be pale yellow or white. All barbels are dark brown or black, except chin barbels, which may be pale.


During development, eggs are pale in colour and about 3 mm in diameter. Young hatch at 6 mm total length, are yellow in colour initially, but will darken soon after hatching. Once swimming and feeding actively, the young resemble tadpoles with very dark colouration and similar body shape. Growth is rapid, with sexual maturity attained by age 3 (203-330 mm total length) in females. Maximum age in Canada is reported as 6-8 years.”

Distribution Table

Top of page

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

ChinaPresent only in captivity/cultivationIntroduced1984Welcomme, 1988; Tan and Tong, 1989Hubei Province and Beijing
-BeijingPresent only in captivity/cultivationIntroduced1984Welcomme, 1988; Tan and Tong, 1989
-HubeiPresent only in captivity/cultivationIntroduced1984Welcomme, 1988; Tan and Tong, 1989
IranPresentIntroducedCoad, 1995
TurkeyPresentIntroducedCoad, 1995
VietnamPresentIntroducedCsavas, 1995

North America

CanadaPresentPresent based on regional distribution.
-British ColumbiaPresent, few occurrencesIntroduced Invasive Scott and Crossman, 1973; Crossman, 1991Occurs in the lower Fraser RIver and lakes on Vancouver Island between Victoria and Nanaimo
-ManitobaLocalisedNative Not invasive Scott and Crossman, 1973
-New BrunswickWidespreadNative Not invasive Scott and Crossman, 1973
-Nova ScotiaWidespreadNative Not invasive Scott and Crossman, 1973
-OntarioWidespreadNative Not invasive Scott and Crossman, 1973Southern Ontario
-QuebecWidespreadNative Invasive Scott and Crossman, 1973
-SaskatchewanLocalisedNative Not invasive Scott and Crossman, 1973
USAPresentCAB ABSTRACTS Data Mining 2001
-AlabamaPresentNative Not invasive Fuller et al., 1999
-ArizonaPresentIntroducedFuller et al., 1999
-ArkansasPresentNative Not invasive Fuller et al., 1999
-CaliforniaPresentIntroducedFuller et al., 1999
-ColoradoPresentIntroducedFuller et al., 1999South Platte drainage; possibly other locations
-ConnecticutPresentNative Not invasive Fuller et al., 1999
-DelawarePresentNative Not invasive Fuller et al., 1999
-FloridaPresentNative Not invasive Fuller et al., 1999
-GeorgiaPresentNative Not invasive Fuller et al., 1999
-HawaiiUnconfirmed recordIntroduced1893Welcomme, 1988; Yamamoto, 1992Introduced to Oahu and Hawaii, probably introduced for aquaculture
-IdahoPresentIntroducedFuller et al., 1999Clearwater and Bear drainages
-IllinoisWidespreadNative Not invasive Fuller et al., 1999
-IndianaWidespreadNative Not invasive Fuller et al., 1999
-IowaWidespreadNative Not invasive Fuller et al., 1999
-KansasPresentIntroducedFuller et al., 1999Cherokee, Crawford and Linn counties
-KentuckyPresentIntroducedFuller et al., 1999Licking, Rolling Fork, Salt, Kentucky drainages
-LouisianaPresentNative Not invasive Fuller et al., 1999
-MainePresentNative Not invasive Fuller et al., 1999
-MarylandPresentNative Not invasive Fuller et al., 1999
-MassachusettsPresentNative Not invasive Fuller et al., 1999
-MichiganWidespreadNative Not invasive Fuller et al., 1999
-MinnesotaPresentNative Not invasive Fuller et al., 1999
-MississippiWidespreadNative Not invasive Fuller et al., 1999
-MissouriPresentNative Not invasive Fuller et al., 1999Lower Missouri drainage including the Chariton-Nishnabotna drainage
-NebraskaPresentIntroducedFuller et al., 1999Truman Reservoir (Osage River); private eastern ponds
-NevadaPresentIntroducedFuller et al., 1999Carson, Truckee, Humbolt, Muddy drainages
-New HampshirePresentNative Not invasive Fuller et al., 1999Androscoggin drainage
-New JerseyPresentNative Not invasive Fuller et al., 1999
-New MexicoPresentIntroducedFuller et al., 1999
-New YorkWidespreadNative Not invasive Fuller et al., 1999
-North CarolinaPresentNative Not invasive Fuller et al., 1999
-North DakotaPresentNative Not invasive Fuller et al., 1999
-OhioPresentNative Not invasive Fuller et al., 1999
-OklahomaPresentNative Not invasive Fuller et al., 1999
-OregonPresentIntroducedFuller et al., 1999Willamette, Klamath, Coos drainages; Devil’s Lake and Benton County
-PennsylvaniaWidespreadNative Not invasive Fuller et al., 1999
-Rhode IslandPresentNative Not invasive Fuller et al., 1999
-South CarolinaWidespreadNative Not invasive Fuller et al., 1999
-South DakotaWidespreadNative Not invasive Fuller et al., 1999
-TennesseePresentNative Not invasive Fuller et al., 1999
-VermontPresentNative Not invasive Fuller et al., 1999
-VirginiaPresentNative Not invasive Fuller et al., 1999
-WashingtonPresentIntroducedFuller et al., 1999Silver Lake (Castlerock); likely other localities
-West VirginiaPresentNative Not invasive Fuller et al., 1999
-WisconsinPresentNative Not invasive Fuller et al., 1999

Central America and Caribbean

Netherlands AntillesPresentIntroduced1900Welcomme, 1988
Puerto RicoPresentIntroduced1915Welcomme, 1988

South America

ChilePresentIntroduced1908 Invasive Welcomme, 1988; Pérez et al., 2003Found in the Angostura and Prado rivers but has recently become extinct in the Angostura

Europe

AustriaUnconfirmed recordIntroducedWelcomme, 1988
BelarusPresentIntroduced1935Reshetnikov et al., 1997Released in lakes and ponds of Western Belorussia (in Lake Orekhovo in the upper reaches of the Pripet, etc.) Reared with the use of thermal waters of the cooling ponds at the power stations.
BulgariaPresentIntroduced1975Mikhov, 2000; Uzunova and Zlatanova, 2007
Czech RepublicPresentIntroducedWelcomme, 1988Established in backwaters of Bohemian and Moravian rivers
DenmarkPresentIntroducedFrier, 1994Hjulby Sø on Bornholm
FinlandPresentIntroduced1922FAO, Food Agriculture Organization of the United Nations; Holcík, 1991Occurs on the coast East of Helsinki and in several small lakes in South Finland.
FrancePresentIntroduced1950Welcomme, 1988
GermanyPresentIntroduced1885Scott and Crossman, 1973Established in open waters. Also used as an ornamental fish in garden ponds.
HungaryPresentIntroduced1902FAO, Food Agriculture Organization of the United Nations
IrelandPresentIntroducedWelcomme, 1988
ItalyPresentIntroduced1906FAO, Food Agriculture Organization of the United Nations; Amori et al., 1993Recently recorded in water bodies of the Piemonte region
NetherlandsPresentIntroduced1900Welcomme, 1988
NorwayPresentIntroducedAppleby, 1999
PolandPresentCAB ABSTRACTS Data Mining 2001; FAO, Food Agriculture Organization of the United Nations; Nowak et al., 2010
RomaniaPresentIntroduced1910FAO, Food Agriculture Organization of the United Nations
Russian FederationUnconfirmed recordIntroducedBogutskaya and Naseka, 2002
SlovakiaPresentIntroduced1899Welcomme, 1988
SpainPresentIntroducedWelcomme, 1988
SwitzerlandPresentIntroducedWittenberg, 2005
UKPresentIntroducedBartley, 2006
UkrainePresentIntroducedMovchan, 1988
Yugoslavia (former)PresentIntroducedWelcomme, 1988

Oceania

New ZealandPresentIntroduced1877FAO, Food Agriculture Organization of the United NationsSome 100-200 fish were released in a lake in Auckland in 1877 and were abundant there by 1885. Also released in a lake in Westland and in the lower reaches of the Waikato River. Widespread in rivers in Auckland, the Wanganui River and Lake Wairarapa as well as in Lake Taupo.

History of Introduction and Spread

Top of page

A. nebulosus was first introduced in the Pacific islands (1877) with the release of 100-200 individuals for angling in Auckland, New Zealand. These introductions resulted in local viable populations by 1885 (Holcík, 1991). Additional introductions for angling and sport occurred in Hawaii in 1893 (Welcomme, 1988).  European introductions occurred concurrently, with individuals from North America introduced to Germany for angling, sport and aquaculture in 1885 (Scott and Crossman, 1973), leading to subsequent intentional and unintentional secondary spread to Poland (1885) (FAO, 1997), the United Kingdom (Bartley, 2006), Hungary (1902) (FAO, 1997), Finland (1922) (FAO, 1997), Belarus (1935) (Reshetnikov et al., 1997) and Bulgaria (1975) (Uzunova and Zlatanova, 2007). Recent introductions (1984) of A. nebulosus from North America to Hubei province and Beijing, China have occurred solely for aquaculture.

Within the United States, A. nebulosus was introduced west of its native Mississippi drainage for angling, sport and aquaculture purposes throughout the 1900s. Introductions within Canada have been concentrated within British Columbia, within the lower Fraser River and lakes within Vancouver Island (Crossman, 1991). The source population, date and reasons for introduction are uncertain for British Columbia populations.

Introductions

Top of page
Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Belarus Germany 1935 Aquaculture (pathway cause) ,
Intentional release (pathway cause)
Yes No Reshetnikov et al. (1997)
British Columbia USA   No No Crossman (1991) Suspected USA source, but some uncertainty
Bulgaria Europe 1975 Aquaculture (pathway cause) ,
Fisheries (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes No Uzunova and Zlatanova (2007)
Chile USA 1908 Aquaculture (pathway cause) Yes No Pérez et al. (2003)
China USA 1984 Aquaculture (pathway cause) No No Welcomme (1988)
Finland Germany 1922 Fisheries (pathway cause) ,
Intentional release (pathway cause)
Yes No FAO (Food Agriculture Organization of the United Nations) (1997)
Germany North America 1885 Aquaculture (pathway cause) ,
Fisheries (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes No Scott and Crossman (1973)
Hawaii California 1893 Fisheries (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
No No Welcomme (1988)
Hungary Germany 1902 Aquaculture (pathway cause) ,
Biological control (pathway cause)
Yes No FAO (Food Agriculture Organization of the United Nations) (1997)
Italy North America 1906 Yes No Amori et al. (1993)
Mississippi 1900s Aquaculture (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
No No
New Zealand USA 1877 Fisheries (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes No Holcík (1991)
Poland Germany 1885 Yes No FAO (Food Agriculture Organization of the United Nations) (1997)
Puerto Rico USA 1915 Fisheries (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes No Welcomme (1988)
UK Italy   Yes No Bartley (2006)

Risk of Introduction

Top of page

Although A. nebulosus is not considered a quarantined pest, several countries (Switzerland (Wittenberg, 2005); Poland (FAO, 1997); Chile (Welcomme, 1988)) report adverse effects on native fish communities following its establishment. The risk of accidental introduction from aquaculture facilities (see Distribution Table for list of facilities) will be dependant upon the type of facility (e.g., enclosed versus wild pens) and proximity to natural waterbodies. Facilities that are physically connected to natural waterbodies likely pose the greatest risk of introduction. Of these facilities, the effectiveness of physical barriers (e.g., netting, electricity) will determine the likelihood of introduction due to potential escapement.

The risk of introduction of A. nebulosus for angling and sport purposes is dependant upon the goals and regulations of fishery management programs (e.g., the encouragement of non-native fish stocking for sport, or biological control) and the prevalence of unauthorized introductions within areas of potential introduction. Although angling for A. nebulosus within Canada is relatively unpopular (Scott and Crossman, 1973), the initial introduction to Europe and the Pacific islands for angling suggests almost global popularity as a sportfish; therefore, unauthorized introductions for angling purposes may occur.

Natural dispersal of wild populations through drainage networks will likely occur given the species’ moderate swimming ability (Scott and Crossman, 1973). In particular, the ability to travel throughout degraded waterbodies is facilitated by the species’ ability to withstand high water temperatures (up to 37.5°C), industrial pollution, and low oxygen concentrations for prolonged periods (Scott and Crossman, 1973). Over-winter survival is also likely high and may not hinder dispersal success, given the species’ ability to tolerate 0.2 ppm oxygen during winter (Scott and Crossman, 1973).

Habitat

Top of page

A. nebulosus prefers warmwater habitats within lakes, ponds, rivers and streams. Coincident with its introduction for aquaculture and sport, it may also inhabit artificial channels (e.g., irrigation ditches; canals) that possess suitably warm water for spawning (21.1°C). Aquatic vegetation is usually necessary, as are mud or sand bottoms. The species is benthic and, therefore, persists most frequently in the nearshore area, but has been captured as deep as 12 m in offshore habitats (Scott and Crossman, 1973). The physiological tolerances of the species allow colonization of very warm (up to 37.5°C) waters with low (as little as 0.2 ppm) dissolved oxygen. The species is frequently found within waters containing substantial domestic and industrial pollution, but may bury within mud substrates to avoid continual exposure to pollutants (Scott and Crossman, 1973).

Habitat List

Top of page
CategoryHabitatPresenceStatus
Brackish
Estuaries Secondary/tolerated habitat Natural
Freshwater
Irrigation channels Secondary/tolerated habitat Productive/non-natural
Lakes Principal habitat Natural
Ponds Principal habitat Productive/non-natural
Reservoirs Principal habitat Productive/non-natural
Rivers / streams Principal habitat Natural

Biology and Ecology

Top of page

Genetics

Hybridization between brown bullhead and black bullhead may occur where the species frequently co-occur (Scott and Crossman, 1973). No other hybrids are known within North America. A. nebulosus has been sequenced and is described in Arai et al. (2001), Hardman and Page (2003)Hubert et al. (2008) and Sullivan et al. (2006).

Reproductive Biology

The spawning behaviour of A. nebulosus was described in detail by Scott and Crossman (1973): “Spawning occurs in late spring and summer in Canada, when water temperatures reach 21.1°C. Regions lacking a yearly cooling period may have repeated spawning events within a single year. During spawning, one or both sexes clear a shallow nest in mud or sand, usually near aquatic vegetation or other available cover (rocks, stumps). Water depth may be between 15 cm and several meters. Spawning sites are usually contained within protected waters (coves, bays, etc.), with spawning occurring during the day. Male and female circle the nest, caressing with barbels. Following deposition, eggs are pale in colour and coated with mucus, 3 mm in diameter. Between 2000-13,000 eggs may be deposited by mature females. Egg care is provided by one or both parents, during which the eggs are fanned continuously with paired fins to increase oxygen concentrations. In Ontario, Canada, eggs take 6-9 days to hatch at 20.6-23.3°C. Immediately following hatching young are 6 mm in length and pale, but soon darken and swim and feed actively. Of note is the spherical swimming pattern that young will follow, which occurs immediately above one or both of the resting parents, until young are 51 mm total length. Growth is rapid with young reaching 51-122 mm by the end of the first growing season.”

Physiology and Phenology

Physiological specializations allow A. nebulosus to tolerate waters contaminated with organic and inorganic pollutants (Scott and Crossman, 1973). The species may also adapt to extremely low dissolved oxygen concentrations and warm waters (Scott and Crossman, 1973). The specific physical mechanisms of these physiological specializations are unknown. Little documentation exists regarding phenological variation in native and exotic ranges.

Nutrition

As an adaptation for prey capture within turbid waters, the species uses oral barbels to sense food items. A. nebulosus is a generalist omnivore, feeding mostly at night and eating benthic organisms that occur frequently within freshwaters: waste, molluscs, immature insects, terrestrial insects, leeches, crustaceans, worms, algae, plant material, fishes and fish eggs (Scott and Crossman, 1973). Young (30-60 mm total length) prefer chironomid larvae, ostracods, amphipods, mayflies and other small aquatic invertebrates (Scott and Crossman, 1973).

Water Tolerances

Top of page
ParameterMinimum ValueMaximum ValueTypical ValueStatusLife StageNotes
Conductivity (µmhos/cm) Optimum Variable
Dissolved oxygen (mg/l) Optimum As low as 0.2 tolerated
Salinity (part per thousand) 0 Optimum 8-15 tolerated
Turbidity (JTU turbidity) Optimum Variable; 100 NTU tolerated (estimated)
Velocity (cm/h) Optimum Low(<0.1 m/s)
Water temperature (ºC temperature) Optimum Preferred unknown; 36.1 tolerated; 37.5 lethal

Natural enemies

Top of page
Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Esox lucius Predator not specific Scott and Crossman, 1973
Esox masquinongy Predator not specific Scott and Crossman, 1973
Esox niger Predator not specific Scott and Crossman, 1973
Sander canadensis Predator not specific Scott and Crossman, 1973
Sander vitreus Predator not specific Scott and Crossman, 1973

Notes on Natural Enemies

Top of page

By virtue of its strong pectoral and dorsal spines, the adult A. nebulosus is well protected from predation by all but the largest fish predators in their native range in Canada (Scott and Crossman, 1973). Although present in juveniles, the spines are less robust making juveniles more susceptible to predation by fishes with a wider range in size. Within its native range, predators include members of the pike family (Esox spp.) and pike perches (Sander spp.) (Scott and Crossman, 1973). Where introduced on the Gulf Islands of British Columbia in Canada, there are no other piscivorous fishes present and, hence, no native predators to introduced A. nebulosus.

Means of Movement and Dispersal

Top of page

Natural Dispersal

A. nebulosus is a moderately strong swimmer (Scott and Crossman, 1973) that is capable of surviving degraded, warmwater freshwater environments; therefore, the species will undoubtedly increase its introduced range through natural dispersal within drainage networks. The magnitude of spread will be dependant upon the spatial configuration of potential habitats and their connectivity via drainage networks. Most natural dispersal within the native range of Canada and the USA has occurred at local levels (Fuller et al., 1999).

Vector Transmission

Although A. nebulosus are predated upon by larger fishes, the likelihood of long-distance dispersal resulting from this vector is low. Most piscivorous fishes are unable to utilize A. nebulosus for food due to their sharp, strong dorsal and pectoral spines that may lock into an erect position when predated upon.

Intentional Introduction

Introduction via fisheries (angling/sport purposes) and aquaculture are the dominant long-distance (national; international) vectors. Intentional introductions by fisheries managers may result in long-distance travel events via stocking from source populations. Aquaculture introductions may have similar magnitudes of spread. For example, China (Beijing and Hubei province) stocked A. nebulosus for aquaculture purposes from USA broodstock (Welcomme, 1988). Unauthorized introductions by anglers also has the potential to contribute to local, national or international events but may be constrained by the effectiveness of certain legal restrictions that prohibit import of live organisms across borders.

Pathway Causes

Top of page
CauseNotesLong DistanceLocalReferences
Aquaculture Yes
Fisheries Yes
Hunting, angling, sport or racing Yes
Intentional release Yes
Interbasin transfers Yes
Interconnected waterways Yes
Live food or feed tradeKnown within native range in Canada (N Mandrak, DFO Canada, personal communication, 2009) Yes

Pathway Vectors

Top of page
VectorNotesLong DistanceLocalReferences
Aircraft Yes
Aquaculture stock Yes
BaitKnown within native range in Canada (N Mandrak, DFO, Canada, personal communication, 2009) Yes Litvak and Mandrak, 1993

Impact Summary

Top of page
CategoryImpact
Cultural/amenity Negative
Economic/livelihood Positive and negative
Environment (generally) Negative
Human health None

Economic Impact

Top of page

To date, economic impacts resulting from A. nebulosus introductions have not been quantified. In certain cases of wild establishment, A. nebulosus introductions have the potential to hinder local commercial and sport fisheries through competition with target species.

Environmental Impact

Top of page

Impact on Habitats

A. nebulosus may increase physical disturbance within freshwaters due to their benthivorous feeding habits. Although their barbels may aid in prey capture, foraging aggressively within substrates may be necessary to dislodge certain benthic prey items, which in-turn can increase turbidity and lead to altered productivity and nutrient cycling. Estimates regarding habitat impacts following A. nebulosus introductions have not been quantified.
 

Impact on Biodiversity

A. nebulosus
introductions may lead to competition for food or space and predation on small fishes, invertebrates or other small food items. Of particular concern is the potential for altered energetic pathways within recipient ecosystems, given their omnivorous diet and a body structure that precludes predation from but all of the largest fishes. Scott and Crossman (1973) describe the following parasites known from within the species, which have the potential to infect recipient fish communities following A. nebulosus introductions: Protozoa, Trematoda, Cestoda, Nematoda, Acanthocephala, leeches, Mollusca, and Crustacea.

Threatened Species

Top of page
Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
GasterosteusNational list(s) National list(s)British ColumbiaCompetition - monopolizing resources; Predation,
Pacifastacus fortis (Shasta crayfish)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered speciesCaliforniaPredationUS Fish and Wildlife Service, 2009

Social Impact

Top of page

A. nebulosus populations may hinder local native sport fisheries by out-competing target fishes, resulting in reduced angling opportunities and their social impacts. Alternatively, introductions may be encouraged locally if A. nebulosus are favoured for sport. Introduction into previously fishless waters may provide new or valued angling opportunities. Current estimates of social impacts resulting from introductions have not been documented.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Fast growing
  • Has high reproductive potential
  • Has high genetic variability
Impact outcomes
  • Altered trophic level
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Modification of natural benthic communities
  • Negatively impacts aquaculture/fisheries
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Competition - monopolizing resources
  • Interaction with other invasive species
  • Predation
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Highly likely to be transported internationally illegally
  • Difficult/costly to control

Uses

Top of page Economic Value

A. nebulosus have been utilized within their native and introduced range primarily for sport and aquaculture, although the species may also be found inadvertently within the aquarium trade, and may be used occasionally as a research laboratory organism (N Mandrak, DFO, Canada, personal communication, 2009). Economic benefits from aquaculture occur primarily within Chile, China, Bulgaria and Belarus (Welcomme, 1988; Tan and Tong, 1989; Reshetnikov et al., 1997; Mikhov, 2000), although the magnitude of these benefits remain uncertain.

Social Benefit

Introduced populations of A. nebulosus to Europe and some Pacific islands originally provided social benefits as sportfish (Welcomme, 1988), but their current social value as sportfish within their introduced range is unknown. Within their native range, the species may be held within zoos or public aquariums (N Mandrak, DFO, Canada, personal communication, 2009).

Environmental Services

Canadian environmental monitoring programs have used A. nebulosus for contaminant biomonitoring within degraded and recovering ecosystems (Arcand-Hoy and Metcalfe, 1999). No other environmental services have been reported.

Uses List

Top of page

Animal feed, fodder, forage

  • Fishmeal

General

  • Botanical garden/zoo
  • Laboratory use
  • Pet/aquarium trade
  • Research model
  • Sport (hunting, shooting, fishing, racing)

Human food and beverage

  • Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

Detection and Inspection

Top of page
A. nebulosus may be detected from shallow waters using conventional fish sampling methods (minnow traps, fyke nets, seines, boat and backpack electrofishers). Once captured, the species may be identified through analysis of meristics and morphometry using the dichotomous key from Scott and Crossman (1973).

Similarities to Other Species/Conditions

Top of page

The brown bullhead (A. nebulosus) is frequently confused with black bullhead Ameiurus melas (southern Canada, USA and parts of Mexico), yellow bullheadAmeiurus natalis (southern Canada, parts of USA), snail bullhead Ameiurus brunneus (southern USA), spotted bullhead Ameiurus serracanthus (southern USA) and flat bullhead Ameiurus platycephalus (southern USA).

A. nebulosus is immediately distinguishable from spotted bullhead by the lack of obvious darkened blotches running the length of the body, whereas a strongly depressed head distinguishes the flat bullhead. Differences between brown, black and yellow bullhead are more conspicuous and concern the morphology of anal rays and pectoral spines. While the yellow bullhead’s anal fin overlaps anterior rays of its caudal fin, both brown bullhead and black bullhead have anal fins that do not reach anterior rays of the caudal fin. Yellow bullhead have relatively smooth pectoral spines; black bullhead possess barbs that point towards head when fins are closed against the body; whereas, the barbs of brown bullhead point towards the caudal fin when closed (Scott and Crossman, 1973; Fuller et al., 1999).

Prevention and Control

Top of page Prevention

Eradication

Eradication may involve the use of chemical agents (e.g., rotenone) to induce mortality within introduced populations, although such methods should be evaluated for their potential effects on non-target fishes. Other measures (e.g., physical removal using fish sampling gears: fyke nets, seines, boat and backpack electrofishers) may also be effective.

Control

Physical/mechanical control

Physical control should involve, if possible, physical isolation of introduced populations, which may require physical (e.g., block nets) or electrical barriers.

Movement control

As with physical control, movement control will involve physical isolation of introduced populations using physical or electrical barriers.

Biological control

Biological control of adult A. nebulosus is unlikely given the paucity of natural predators within the native range, although juveniles may be predated upon by certain large-bodied fishes (e.g., Esox spp. within native range).

Monitoring and Surveillance

Population monitoring will involve physical sampling of invaded and potentially invaded freshwaters using conventional fish sampling methods (minnow traps, fyke nets, seines, boat and backpack electrofishers).

Gaps in Knowledge/Research Needs

Top of page

Several authors have described A. nebulosus introductions to broad geographical areas (e.g., Welcomme, 1988), but such reports typically lack details of specific biological and economic impacts due to their substantial geographic scope. Therefore, future research should describe the complete biological and economic impacts associated with local A. nebulosus introductions, which would allow for better understanding of the risks associated with intentional or unintentional A. nebulosus introductions. Determining the economic benefits of A. nebulosus aquaculture should also be described, which would allow fishery managers to evaluate its use given the potential for inadvertent biological and economic harm.

References

Top of page

Amori G, Angelici FM, Frugis S, Gandolfi G, Groppali R, Lanza B, Relini B, Vicini G, 1993. [English title not available]. (Vertebrata) In: Checklist Delle Specie Della Fauna Italiana [ed. by Minelli A, Ruffo S, Posta La] Calderini, Bologna, , 83 pp

Appleby C, 1999. A list of Norwegian common names of fishes. FishBase [ed. by Froese R, Pauly]. http://www.fishbase.org

Arcand-Hoy LD, Metcalfe CD, 1999. Biomarkers of exposure of brown bullheads (Ameiurus nebulosus) to contaminants in the lower Great Lakes, North America. Environmental Toxicology and Chemistry, 18:740-749

Bailey RM, Robbins CR, 1988. Changes in North American fish names, especially as related to the International Code of Zoological Nomenclature, 1985. Bulletin of Zoological Nomenclature, 45:92-103

Bartley DM, 2006. Introduced species in fisheries and aquaculture: information for responsible use and control. Rome, Italy, FAO: unpaginated

Bogutskaya NG, Naseka A, 2002. An overview of nonindigenous fishes in inland waters of Russia. Proc. Zool. Inst. Russ. Acad. Sci, 296:21-30

Coad BW, 1995. Freshwater fishes of Iran. Acta Sci. Nat. Acad. Sci. Brno, 29(1):1-64

COSEWIC (Committee on the Status of Endangered Wildlife in Canada), 2009. COSEWIC species database. Ottawa, Ontario, Canada. http://www.cosewic.gc.ca

Crossman EJ, 1991. Introduced freshwater fishes: A review of the North American perspective with emphasis on Canada. Canadian Journal of Fisheries and Aquatic Sciences, 48(1):46-57

Csavas I, 1995. Status and perspectives of culturing catfishes in East and Southeast Asia. In: Proceedings of the 1st International Workshop on the Biological Bases for Aquaculture of Siluriformes, Montpellier, France, 23-27 May 1994

FAO (Food Agriculture Organization of the United Nations), 1997. FAO database on introduced aquatic species. Rome, Italy: Food and Agriculture Organization of the United Nations. http://www.fao.org/fishery/dias/en

Frier JO, 1994. [English title not available]. (Danske ferskvandsfisk og deres udbredelsesomrade.) In: Truede ferskvandsfiskearter i Norden. TemaNord [ed. by Frier JO], 4-6, 83-99

Fuller PL, Nico LG, Williams JD, 1999. Nonindigenous fishes introduced into inland waters of the United States. Bethesda, Maryland, USA: American Fisheries Society. [American Fisheries Society, Special Publication 27]

Hardman M, Page LM, 2003. Phylogenetic relationships among Bullhead catfishes of the genus Ameiurus (Siluriformes: Ictaluridae). Copeia, 3(1):20-33

Holcík J, 1991. Fish introductions in Europe with particular reference to its central and eastern part. Canadian Journal of Fisheries and Aquatic Sciences, 48(Suppl.1):13-23

Hubbs CL, Lagler DF, 1957. Fishes of the Great Lakes Region. Michigan, United States: Bulletin of the Cranbrook Institute of Science, No. 26:135 pp

Hubert N, Hanner R, Holm E, Mandrak NE, Taylor E, Burridge M, Watkinson D, Dumont P, Curry A, Bentzen P, Zhang J, April J, Bernatchez L, 2008. Identifying Canadian freshwater fishes through DNA barcodes. Plos One, 3(6):e2490

ISSG (Invasive Species Specialist Group), 2009. ISSG database on global invasive species. Auckland, New Zealand: Invasive Species Specialist Group and IUCN Species Survival Commission. http://www.issg.org/database/welcome/

Litvak MK, Mandrak NE, 1993. Ecology of freshwater baitfish use in Canada and the United States. Fisheries, 18(12):6-13

Maya Arai, Assil IQ, Abou-Samra AB, 2001. Characterization of three corticotropin-releasing factor receptors in catfish: a novel third receptor is predominantly expressed in pituitary and urophysis. Endocrinology, 142(1):446-454

Mikhov S, 2000. Checklist of fishes of Bulgaria. FishBase checklist. http://www.fishbase.org

Movchan YV, 1988. Fauna of Ukraine. Naukova dumka, Kiev, : Publishing House, 367

Nowak M, Kosco J, Popek W, Epler P, 2010. First record of the black bullhead Ameiurus melas (Teleostei: Ictaluridae) in Poland. Journal of Fish Biology, 76(6):1529-1532

Pérez JE, Alfonsi C, Nirchio M, Muñoz C, Gómez JA, 2003. The introduction of exotic species in aquaculture: a solution or part of the problem? Interciencia, 28(4):234-238

Reshetnikov YS, Bogutskaya N, Vasil'eva E, Dorofeeva E, Naseka A, Popova O, Savvaitova K, Sideleva V, Sokolov L, 1997. An annotated check-list of the freshwater fishes of Russia. Journal of Ichthyology, 37:687-736

Robins CR, Bailey RM, Bond CE, Brooker JR, Lachner EA, Lea RN, Scott WB, 1980. A list of common and scientific names of fishes from the United States and Canada. A list of common and scientific names of fishes from the United States and Canada., Ed. 4:174pp

Scott WB, Crossman EJ, 1973. Freshwater Fishes of Canada. Bulletin 184, NO. 184:966 pp

Sullivan JP, Lundberg JG, Hardman M, 2006. A phylogenetic analysis of the major groups of catfishes (Teleostei: Siluriformes) using rag1 and rag2 nuclear gene sequences. Molecular Phylogenetics and Evolution, 41(3):636-662. http://www.sciencedirect.com/science/journal/10557903

Tan Y, Tong HE, 1989. The status of the exotic aquatic organisms in China. Proceedings of the Workshop on Introduction of Exotic Aquatic Organisms in Asia. Asian Fisheries Society Special Publication [ed. by Silva SSDe], 35-43

US Fish and Wildlife Service, 2009. Shasta crayfish, Pacifastacus fortis, 5-year review: Summary and evalution. In: Shasta crayfish, Pacifastacus fortis, 5-year review: summary and evalution : US Fish and Wildlife Service.22 pp.

Uzunova E, Zlatanova S, 2007. A review of the fish introductions in Bulgarian freshwaters. Acta Ichthyologica et Piscatoria, 37(1):55-61. http://www.aiep.pl/index.html

Welcomme RL, 1988. International introductions of inland aquatic species. FAO Fisheries Technical Paper No. 294. Rome, Italy: FAO, 318 pp

Wittenberg R, 2005. An inventory of alien species and their threat to biodiversity and economy in Switzerland. CABI Bioscience Switzerland Centre report to the Swiss Agency for Environment, Forests and Landscape. The environment in practice 0629. Bern, : Federal Office for the Environment, 155

Yamamoto MN, 1992. Occurrence, distribution and abundance of accidentally introduced freshwater aquatic organisms in Hawaii. State of Hawaii, Freshwater Fisheries Research and Surveys, Proj. No. F-14-R-16

Links to Websites

Top of page
WebsiteURLComment
SARA Registry (Canada)www.sararegistry.com

Organizations

Top of page

USA: United States Geological Survey: Nonindigenous Aquatic Species, Florida Integrated Science Center (FISC), Gainesville, FL 32653

Contributors

Top of page

16/03/09 Original text by:

Nicholas Mandrak, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Canada

Andrew Drake, University of Toronto, Canada

Distribution Maps

Top of page
You can pan and zoom the map
Save map