The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Cercopagis pengoi
Cercopagis pengoi
(fishhook waterflea)

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Cercopagis pengoi

Common name: fishhook waterflea

Synonyms and Other Names: fish-hook water flea

Taxonomy: available through www.itis.govITIS logo

Identification: Body size from 1–3 mm in length without tail, 6–13 mm with tail; tail has three pairs of barbs and a characteristic loop near the end.

Size: 6 to 13 mm including tail

Native Range: Black, Caspian, Azov, and Aral seas of Europe and Asia (Makarewicz et al. 2001)

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, 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 Cercopagis pengoi are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
IL199920212Chicago; Lake Michigan
MI199920045Detroit; Lake Huron; Lake Michigan; Lake Superior; Muskegon
NY199820235Lake Champlain; Lake Erie; Lake Ontario; Lower Hudson; Seneca
OH200120051Lake Erie
PA200220021Lake Erie
WI200020021Lake Michigan

Table last updated 7/24/2024

† Populations may not be currently present.

Ecology: Cercopagis pengoi lives in brackish and freshwater lakes. It exhibits diurnal vertical migrations in its native range and feeds on other zooplankton.

In addition to sexual reproduction, Cercopagis most commonly reproduces parthenogenically (asexually) during the summer, which allows it to quickly establish new populations with a relatively small seed population without the need for a large number of the smaller males along with females. Eggs produced in the early part of the season are delicate and very susceptible to damage, with low recruitment rates. Later in the season, as surface water temperatures decline, Cercopagis females switch to sexual reproduction, producing over-wintering or resting eggs (the species is also known to produce resting eggs anytime during the year when environmental conditions become inhospitable). Such resting eggs can successfully overwinter in an inactive state and replenish the population after hatching in the spring. Resting eggs are also resistant to desiccation, freeze-drying and ingestion by predators (such as other fish). They can be easily transported to other drainage basins by various vectors, particularly if they are still in the female's body (the barbed caudal spine allows attachment to ropes, fishing lines, waterfowl feathers, aquatic gear, vegetation and mud). Resting eggs can hatch regardless of whether the carrier female is alive or dead.

Means of Introduction: Ballast water, boating

Status: Considered established in Lake Ontario, establishing itself quickly (similar to the invasion patterns in Europe) in the other Great Lakes (except L. Huron and Superior) and other inland lakes due to recreational boat traffic and other human activities (USEPA 2008).

Impact of Introduction: Cercopagis pengoi is a consumer of  other zooplankton. As such it competes with other planktivores of the Great Lakes, including the alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) (Bushnoe et al. 2003). Its long spine makes it less palatable to planktivorous fish. For these reasons C. pengoi could have a serious effect on the food supply of planktivores. For example, yearling alewife compete directly with C. pengoi because they are planktivorous, and cannot consume C. pengoi due to the caudal appendage. Once alewife reach their first year they are large enough to handle the caudal appendage (Bushnoe et al. 2003). Cercopagis pengoi's establishment in Lake Ontario in 1998 corresponded with the lowest alewife populations in twenty years (Makarewicz et al. 2001). Cercopagis pengoi also fouls fishing gear.

A 2002 study of the food web impacts of C. pengoi showed that the depth at which C. pengoi exists is depleted of small organisms (<0.15 mg) (Benoit et al. 2002). It is unclear as to whether this is due to predator evasion or C. pengoi consumption, but in either case the smaller organisms are forced into deeper, cooler strata, causing growth rate changes (Benoit et al. 2002). The full impact of C. pengoi on the food web has not yet been extensively studied.

Remarks: Cercopagis pengoi has been found in the stomach of some fishes in high percentages in Europe.

According to the EPA's GARP model, C. pengoi, a free-swimming macroinvertebrate, would likely find suitable habitat throughout the Great Lakes region, except for the deeper waters of Lake Superior. However, population densities of the fishhook water flea increase with distance from shore (IUCN 2010), suggesting that this species may be able to occupy the entire region, including the deeper waters of Lake Superior, given sufficient time (USEPA 2008).

References: (click for full references)

Benoit, H.P., O.E. Johannsson, D.M. Warner, W.G. Sprules, and L.G. Rudstam. 2002. Assessing the impact of a recent predatory invader: the population dynamics, vertical distribution, and potential prey of Cercopagis pengoi in Lake Ontario. Limnolology and Oceanography 47(3):626-635.

Bushnoe, T.M., D.M. Warner, L.G. Rudstam, and E.L. Mills. 2003. Cercopagis pengoi as a new prey item for alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in Lake Ontario. Journal of Great Lakes Research 29(2):205-212.

Cavaletto, J., H. Vanderploeg, R. Pichlová-Ptácníková, S. Pothoven, J. Liebig, and G.L. Fahnenstiel. 2010. Temporal and spatial separation allow coexistence of predatory cladocerans: Leptodora kindtii, Bythotrephes longimanus, and Cercopagis pengoi, in southeastern Lake Michigan. Journal of Great Lakes Research 36(SP3):65-73.

Charlebois, P.M., M.J. Raffenberg, and J.M. Dettmers. 2001. First occurrence of Cercopagis pengoi in Lake Michigan. Journal of Great Lakes Research 27(2):258-261.

GLMRIS. 2012. Appendix C: Inventory of Available Controls for Aquatic Nuisance Species of Concern, Chicago Area Waterway System. U.S. Army Corps of Engineers.

Gorokhova, E., T. Fagerberg, S. Hansson. 2004. Predation by herring (Clupea harengus) and sprat (Sprattus sprattus) on Cercopagis pengoi in a western Baltic Sea bay. ICES Journal of Marine Science 61(6):959-965.

International Union for Conservation of Nature (IUCN). 2010. Cercopagis pengoi. Global Invasive Species Database. http://www.issg.org/database/species/ecology.asp?fr=1&si=118

Jacobs, M.J., and H.J. MacIsaac. 2007. Fouling of fishing line by the waterflea Cercopagis pengoi: a mechanism of human-mediated dispersal of zooplankton? Hydrobiologia 583(1):119-126.

Laxson, C.L., K.N. McPhedran, J.C. Makarewicz, I.V. Telesh, and H.J. MacIsaac. 2003. Effects of the non-indigenous cladoceran Cercopagis pengoi on the lower food web of Lake Ontario. Freshwater Biology 48(12):2094-2106.

Litvinchuk, L.F., and I.V. Telesh. 2006. Distribution, population structure, and ecosystem effects of the invader Cercopagis pengoi (Polyphemoidea, Cladocera) in the Gulf of Finland and the open Baltic Sea. Oceanologia 48 (S):243-257.

Makarewicz, J.C., I.A. Grigorovich, E. Mills, E. Damaske, M.E. Cristescu, W. Pearsall, M.J. LaVoie, R. Keats, L. Rudstam, P. Hebert, H. Halbritter, T. Kelly, C. Matkovich, and H.J. MacIsaac. 2001. Distribution, fecundity, and genetics of Cercopagis pengoi (Ostroumov) (Crustacea, Cladocera) in Lake Ontario. Journal of Great Lakes Research 27(1):19-32.

Ojaveer, H., L.A. Kuhns, R.P Barbiero, and M.L. Tuchman. 2001. Distribution and population characteristics of Cercopagis pengoi in Lake Ontario. Journal of Great Lakes Research 27(1):10-18.

Ontario's Invading Species Awareness Program. Spiny and Fishhook Waterfleas. http://www.invadingspecies.com/invaders/invertebrates/spiny-and-fishhook-waterflea/. Accessed on 05/31/2013.

Pichlová, R., and J. Vijverberg. 2001. A laboratory study of functional response of Leptodora kindtii to some cladoceran species and copepod nauplii. Archiv für Hydrobiologie 150(4):529-544.

Pichlová-Ptácniková, R., and H.A. Vanderploeg. 2009. The invasive cladoceran Cercopagis pengoi is a generalist predator capable of feeding on a variety of prey species of different sizes and escape abilities. Fundamental and Applied Limnology 173 (4): 267-279.

Pimentel, D. 2005. Aquatic nuisance species in the New York State Canal and Hudson River systems and the Great Lakes basin: an economic and environmental assessment. Environmental Management 35(5):692-701.

Pothoven, S. A., H. A. Vanderploeg, S. A. Ludsin, T. O. Hook and S. B. Brandt. 2009. Feeding Ecology of emerald shiners and rainbow smelt in Central Lake Erie. Journal of Great Lakes Research 35(2):190-198.

Pothoven, S.A., H.A. Vanderploeg, J.F. Cavaletto, D.M. Krueger, D.M. Mason, and S.B. Brandt. 2007. Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan. Freshwater Biology 52(3):561-573.

Stewart, T.J., W.G. Sprules, and R. O’Gorman. 2009. Shifts in the diet of Lake Ontario alewife in response to ecosystem change. Journal of Great Lakes Research 35(2):241-249.

Stewart, T.J., O.E. Johannsson, K. Holeck , W.G. Sprules, and R. O’Gorman. 2010. The Lake Ontario zooplankton community before (1987-1991) and after (2001-2005) invasion-induced ecosystem change. Journal of Great Lakes Research 36(4):596-605.

Storch, A., K. Schulz, C. Cáceres, P. Smyntek, J. Dettmers, and M. Teece. 2007. Consumption of two exotic zooplankton by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in three Laurentian Great Lakes. Canadian Journal of Fisheries and Aquatic Science 64(10):1314-1328.

Therriault, T.W., I.A. Grigorvich, D.D. Kane, E.M. Haas, D.A. Culver, and H.J. MacIsaac. 2002. Range expansion of the exotic zooplankter Cercopagis pengoi (Ostroumov) into western Lake Erie and Muskegon Lake. Journal of Great Lakes Research 28(4):698-701.

Thompson, E., J.C. Makarewicz, and T.W. Lewis. 2005. Additional link in the food web does not biomagnify a persistent contaminant in Lake Ontario: the case of Cercopagis pengoi. Journal of Great Lakes Research 31(2):210-218.

U.S. Environmental Protection Agency (USEPA). 2008. EPA Monitoring Data. EPA Great Lakes National Program Office. Available http://www.epa.gov/grtlakes/monitoring/biology/exotics/cercopagis.html

Vanderploeg, H.A., T.F. Nalepa, D.J. Jude, E.L. Mills, K.T. Holeck, J.R. Leibig, I.A. Grigorovich, and H. Ojaveer. 2002. Dispersal and emerging ecological impacts of Ponto-Caspian species in the Laurentian Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences 59(7):1209-1228.

Warner, D., L.G. Rudstam, H. Benoit, E.L. Mills, and O. Johannsson. 2006. Changes in seasonal nearshore zooplankton abundance patterns in Lake Ontario following establishment of the exotic predator Cercopagis pengoi. Journal of Great Lakes Research 32(3):531-542.

Witt, A.M., J.M. Dettmers, and C.E. Cáceres. 2005. Cercopagis pengoi in southwestern Lake Michigan in four years following invasion. Journal of Great Lakes Research 31(3):245-252.

Author: Benson, A., E. Maynard, D. Raikow, J. Larson, T.H. Makled, and A. Fusaro

Revision Date: 9/12/2019

Citation Information:
Benson, A., E. Maynard, D. Raikow, J. Larson, T.H. Makled, and A. Fusaro, 2024, Cercopagis pengoi: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=163, Revision Date: 9/12/2019, Access Date: 7/24/2024

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.


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Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/24/2024].

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