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Fishhook
Waterflea (Cercopagis pengoi)
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Photo:
Dr.
Igor A Grigorovich, University of Windsor
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Introduction
~Description
~Impacts
Geographic Information
~Origin
~Distribution
Control
Picture Collections
Educational Resources
Related Sites
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INTRODUCTION |
| DESCRIPTION
Actual size = 1 cm.
Image: Ontario
Federation of Anglers and Hunters
Cercopagis pengoi is the latest exotic crustacean
to invade the Great Lakes. This predatory cladoceran (order containing
waterfleas) was first identified by Canadian scientists in early August
of 1998, and was reported via Internet by Dr. Hugh MacIsaac at the end
of August. It is commonly called the "fishhook waterflea" because
of its long tail that ends in a "hook." This characteristic of the prolific
breeder causes them to catch on fishing lines and nets, fouling the angler's
gear. Cercopagis is similar to another recent invader in the Great
Lakes, Bythotrephes cederstroemi (spiny waterflea). Both Cercopagis and
Bythotrephes belong to the family Cercopagididae, and have long tail
structures with barbs along the end closest to the rest of the animal. Both species occur in brackish and pure freshwater environments.
Cercopagis is a voracious predator that devours small plankton essential
to the diet of larval fish. In addition to sexual reproduction, Cercopagidids
most commonly reproduce parthenogenically (can develop from unfertilized eggs), which allows them to quickly
establish new populations with a relatively small seed population.
source: GLNPO Biological
Monitoring Program
March 2001 [J. Great Lakes Res., 27(1)] |
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IMPACTS:
PROBLEMS FOR THE ECOSYSTEM
Although it is too early to verify the impacts
that Cercopagis may have on the Great Lakes’ ecosystem, scientists are
concerned that its high reproductive rate will lead to high population
densities. Cercopagis can produce up to 13 offspring at one time, reproduce
numerous times in one season, and produce “resting eggs” which can remain
dormant over the winter. Cercopagis is a large type of zooplankton (small
animals that live and swim within the water column). It eats smaller zooplankton
which are also important food items for the larval fish of most species.
Zooplankton are also an important food source for forage fish that are
eaten by larger sport and commercial fish. The food chain that these zooplankton
are involved in looks like this:
algae --> small zooplankton --> C. pengoi
and other large zooplankton -->
forage fish --> sport fish --> humans
Scientists are concerned that
a large population of Cercopagis could deplete the population of smaller
zooplankton and thereby reduce growth and survival of important fish species.
Scientists hope that Cercopagis will become an important food item for
fish, but are concerned that the long tail will make it difficult for small
fish to handle. Research is vital to determine the full impact of Cercopagis
on the biodiversity and ecology of the Great Lakes’ ecosystem.
ECOLOGICAL PROBLEMS
FOR LAKE ERIE
Because Lake Erie is the southernmost, shallowest,
warmest, and most biologically productive of the Great Lakes, it is likely
that Cercopagis will thrive in Lake Erie and that lake's populations will therefore
be the largest. As a result, the impact in Lake Erie could be greater than
in the other Great Lakes. This is certainly not good news for the yellow perch
and walleye populations.
PROBLEMS FOR FISHERMEN
Since Cercopagis can achieve very high population
densities in
lakes during the summer, anglers may get frustrated
by its long
spiny tail, which is easily snagged by fishing
lines and nets.
Anglers are most likely to encounter Cercopagis
on their fishing
lines in clumps of hundreds of individuals. The
waterflea's long
spiny tail can become entangled on fishing lines,
creating havoc
for anglers as the first line guide of their fishing
rod becomes
clogged with hundreds of Cercopagis. Anglers have
reported
having to cut their lines because they are unable
to reel them in.
Source:
Aquatic Nuisance Species Alert
Publication
OHSU.FS.083 |
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GEOGRAPHICAL
INFORMATION |
ORIGIN
Cercopagis is native to the
Caspian Sea. However, the invader spread within Europe and then to
North America. Confirmed reports of Cercopagis have been limited
to Lake Ontario, Lake Michigan, Lake Erie, and several inland lakes in
New York State. Cercopagis was probably carried to the Great Lakes
in the ballast water of a foreign ship and released when the ship released
ballast water as it took on cargo.
Image: Ontario
Federation of Anglers and Hunters.
Source: Wisconsin
Sea Grant |
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DISTRIBUTION |
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Image: Geographic
Information System “INVADER”
Source:
http://www.caspianenvironment.org/biodb/eng/zooplankton/Cercopagis%20pengoi/main.htm
DETAILED
IMAGE OF GREAT LAKES DISTRIBUTION
Rate of Distribution
By late 1999, less than a year after its initial
discovery in Lake
Ontario, Cercopagis had invaded at least six Finger
Lakes in
New York state, as well as Grand Traverse Bay in
northern
Lake Michigan, and southern Lake Michigan. Any
recreational
boat and fishing or diving gear that has been used
in these
waters will likely be contaminated and can spread
the animal
to other bodies of water, such as Lake Erie.
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Source:
Twine Line, Ohio Sea Grant Newsletter
Vol.
22/No. 4
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CONTROL
METHODS |
Control
Although Cercopagis has become established in several
parts of Lake Ontario, its spread to other Great Lakes and our inland lakes can be prevented or slowed.
Boaters and anglers are urged to take the following precautions to help
prevent the spread of Cercopagis and other exotic species by taking the following actions:
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Thoroughly clean your fishing and diving gear, nets, and
boats before moving from one lake to another.
• Drain water from motor, live well, bilge, and transom
wells while on land before leaving the area.
• Empty bait buckets on land upon leaving the water
at the end of the day - do this before leaving the area.
• Do not release live bait into a body of water or release
animals from one waterbody to another.
• Discard contaminated line and nets that will not come
clean.
Source:
Twine Line, Ohio Sea Grant Newsletter
Vol.
22/No. 4
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| PICTURE
COLLECTIONS (Click image for link) |
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Credit:
Wisconsin Sea Grant
A cluster of Cercopagis |
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Credit:
Wisconsin Sea Grant
The fishhook waterflea accumulates
on trolling lines and can clog the tip top guide on fishing poles, making
it difficult to reel in the fish. |
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Credit:
Jim
Dusen
State University
College at Brockport study of Fishhook Waterflea |
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Credit:
Radka Pichlova & Hank Vanderploeg
Top: Fishhook
waterflea (Cercopagis pengoi)
Bottom: Spiny
waterflea (Bythotrephes cederstroemi) |
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Credit:
Mirja Rosenberg
(Cercopagis pengoi) |
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RELATED
SITES |
RBIC
Information system serves as a Regional Clearinghouse on invasive alien
species and an information hub of the Global Invasive Species International
Network.
US
EPA Great Lakes Activities site featuring International activities, sediment
work, ecosystems, invasive species, monitoring and research activities,
pollution prevention, and outreach programs.
The
Great Lakes Commission is a binational public agency dedicated to the use,
management and protection of the water, land, and other natural resources
of the Great Lakes-St. Lawrence system.
www.issg.org/database/species/list.asp
Complete Global list of Invasive species (by
scientific name).
www.seagrant.wisc.edu/outreach/nis/Fishhook.html
National information center that contains a
comprehensive collection of research publications and education materials
on aquatic nuisance species.
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EDUCATIONAL
LINKS FOR INVASIVE SPECIES RESOURCES |
www.epa.gov/region5/enved/resources.html
www.gfawesome.org/mad_science/activities.html
www.iiseagrant.org/EXOTICSP/
www.seagrant.umn.edu/education/index.html |
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REFERENCES |
Aquatic Nuisance Species Alert
Publication
OHSU.FS.083 |
GLNPO Biological Monitoring Program
March 2001 [J. Great Lakes Res., 27(1)] |
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