STATE OF THE GREAT LAKES 2005
WHY ARE NON-NATIVE AQUATIC SPECIES A PROBLEM IN THE GREAT LAKES
AND HOW ARE THEY GETTING HERE?
The introduction and spread of non-native aquatic species threaten the ecology and economy of the Great Lakes
region. Human activities associated with shipping are responsible for over one-third of the non-native aquatic
species introductions to the Great Lakes.
The Issues
• The Great Lakes have been changed forever by
the introduction of at least 169 non-native
aquatic species. The spread of non-native species
is one of the most serious threats to the integrity
of the Great Lakes ecosystem.
• Once a non-native species establishes itself in the
Great Lakes ecosystem, it is virtually impossible
to eliminate. For this reason, further invasions
must be prevented.
• Non-native aquatic species also impose a serious
toll on the economy of the region. Sea lamprey
controls alone currently cost governments over
$16 million annually. Non-native aquatic species
also threaten the sport and commercial fishing
industry that is valued at almost $4.5 billion
annually and supports more than 80,000 jobs.
The Indicators
The introduction of non-native aquatic species to
the Great Lakes has lead to unpredictable and
irreversible changes to the ecosystem. Documenting
the presence of these species and their modes of
introduction into the Great Lakes allows assessment
of the health of the ecosystem and identifies
mechanisms by which to prevent further invasions.
Sea lamprey abundance is an example of an
indicator directly related to the damage that non-
native aquatic species can inflict upon fish
communities and aquatic ecosystems of the Great
Lakes. The eel-like sea lamprey is a parasite that
feeds on the body fluids of other fish. Its invasion
into the upper lakes in the early 1900s led to the
devastation of many native fish populations,
particularly top predators such as lake trout.
The Assessment
Human activities associated with shipping are
responsible for over one-third of the non-native
species introductions to the region. In fact, since the
opening of the St. Lawrence Seaway in 1959, over 70
percent of non-native animal introductions have
been attributed to the release of contaminated
ballast water into the Great Lakes or from biofouling
(the undesirable accumulation of organisms) on the
hulls of ocean-going ships. Ballast water is carried
by ocean-going ships for stability and is exchanged
at various ports. In the 1980s, after the introduction
of the Eurasian ruffe and the zebra mussel,
voluntary ballast management measures were put
into effect. This was followed by mandated
regulations in 1993. Contrary to expectations, the
reported rate of invasion has not declined since
these measures began. Current enforcement
practices and treatment technologies may be
inadequate to prevent additional invasions.
Animals
Plants
/ / / /
. y >
Method of Introduction
Methods of introduction for non-native aquatic species
established in the Great Lakes basin since the 1830s.
Source: State of the Great Lakes 2005 report.
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WHY ARE NON-NATIVE AQUATIC SPECIES A PROBLEM IN
THE GREAT LAKES AND HOW ARE THEY GETTING HERE?
Other methods of non-native aquatic species
introduction to the Great Lakes include their direct
release by humans, unintentional transfer or escape
from captivity. Of particular concern are activities
related to aquaria, garden ponds, baitfish, and live
fish markets. For example, bighead and silver carp,
fish species reported to have escaped from
aquaculture facilities and fish farm ponds adjacent
to the Mississippi River in the 1980s and 1990s, have
become established in the Mississippi River Basin.
These species are now making their way upstream
in the Illinois River toward Lake Michigan, and they
may still be used for live bait by anglers and sold
live at some fish food markets within the Great
Lakes region.
Sea lamprey, documented in Lake Ontario since the
early 1800s, invaded the other Great Lakes after the
Welland Canal between Lake Ontario and Lake Erie
opened in 1920. Lampricide treatments are the
mainstay of control and have reduced sea lamprey
populations to levels that allow lake trout to
survive to maturity in all five Great Lakes and to be
fully self-sustaining in most areas of Lake Superior.
Target ranges of sea lamprey abundance have been
set by the Great Lakes Fishery Commission (GLFC)
and fishery management agencies. Sea lamprey
populations are still above target levels in all three
upper Great Lakes and are increasing in abundance
in Lake Michigan.
Sea lamprey and
wounded coho
salmon. Photo: Roger
Bergsted (USGS) and
Marc Gaden (GLFC).
Current Actions
Connecting channels and canals continue to allow
non-native aquatic species access o the Great Lakes.
In response to the threat of the Asian carp invasion
in the Great Lakes, an electric dispersal barrier in
the Chicago Sanitary and Ship Canal was activated
in 2002 to block the movement of species between
the Mississippi River and the Great Lakes basins.
Construction of a second dispersal barrier is
underway. Although all eight Great Lake states and
the province of Ontario have issued some
restrictions on the sale of live Asian carp in markets,
enforcement in private sales remains a challenge.
Measures have been established to control sea
lamprey, including treating larval lamprey habitats
in streams with lampricides, trapping spawning
lamprey, and the release of sterile male lamprey.
The GLFC continues to focus on research and
development of alternative control strategies to
improve the effectiveness of the control program
and to reduce reliance on lampricides.
Outreach efforts have been initiated to educate
recreational water users and management agencies
about practices that reduce the spread of non-native
aquatic species.
Actions Needed
To be effective in preventing new invasions,
management strategies must focus on linkages
between non-native aquatic species and their modes
of travel between their native habitat and the Great
Lakes. Measures are needed that will effectively
eliminate or minimize the role of shipping and other
methods of introduction. If this does not occur, we
can expect the number of non-native aquatic species
in the Great Lakes to continue to rise, with an
associated loss of native biodiversity and an
increase in unpredicted ecological damage.
To Learn More
For further information on non-native aquatic
species in the Great Lakes, refer to the State of the
Great Lakes 2005 report which, along with other
Great Lakes references, can
be found at
www.epa.gov/glnpo/solec.
Zebra mussels. Photo: U.S. EPA
Great Lakes National Program
Office.
02/06
EPA 905-F-06-903
IISG-05-29
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