Federal Management of Sea Lampreys in the Great Lakes and Lake Champlain

Federal Management of Sea Lampreys in the Great Lakes and Lake Champlain

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September 25, 2023
Federal Management of Sea Lampreys in the Great Lakes and
Lake Champlain
The sea lamprey (Petromyzon marinus), sometimes known
nuisance species that threatens native fish populations in the
as the vampire fish (Figure 1), is a parasitic fish species
Great Lakes.
native to the northern Atlantic Ocean and the waters of
eastern United States and western Europe. By the early
Figure 2. Sea Lamprey Range in the United States
1900s, sea lampreys had spread throughout the Great Lakes,
where they harm economically important fish species such
as Atlantic salmon (Salmo salar), lake trout (Salvelinus
namaycush), and lake sturgeon (Acipenser fulvescens).
According to some estimates, fish wounded by sea
lampreys have a mortality rate of 40%-60% and a single
lamprey can kill approximately 40 pounds of fish per year.
Congress is interested in efforts to control sea lamprey
populations and the impacts of these efforts on the health of
fisheries, recreation industries, and ecosystems of the Great
Lakes and Lake Champlain. This product provides an
overview of the biology and spread of sea lamprey, federal
sea lamprey control programs, and selected considerations
for Congress.
Figure 1. Sea Lamprey Mouth

Source: U.S. Geological Survey.
Sea Lamprey Biology
The biology of sea lampreys is relevant to control efforts,
many of which are designed to target specific stages of the
species’ complex life history. Sea lamprey populations from
the northern Atlantic are anadromous, meaning individuals
are born in freshwater, spend a part of their lives in
saltwater, and then return to freshwater streams to spawn

(Figure 3).
Source: U.S. Geological Survey.
Notes: Injuries and loss of fluids from sea lamprey feeding can cause
the death of the host fish.
Geographic Range of the Sea Lamprey
In the United States, sea lampreys occupy offshore, coastal,
and inland waters from the Gulf of St. Lawrence to northern
Florida and the Great Lakes region (Figure 2). Sea
lampreys were first observed in the Great Lakes in the
1830s. According to scientists, sea lampreys entered Lake
Ontario from the Atlantic Ocean through human-made
shipping channels and were found in all of the Great Lakes
by 1938. Genetic evidence suggests sea lampreys may be
native to Lakes Ontario and Champlain, both of which are
accessible from the Atlantic Ocean by water. Some
scientists challenge this view, however, stating that there
are few records of sea lampreys or fish with lamprey
wounds in these lakes prior to the mid-1800s. Regardless of
origin, many stakeholders consider sea lampreys to be a
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Federal Management of Sea Lampreys in the Great Lakes and Lake Champlain
Figure 3. Sea Lamprey Lifecycle
universities; and state, provincial, and tribal entities.
Legislation that addresses aquatic invasive species has
typically established that the GLFC retains authority and
responsibility to implement a comprehensive sea lamprey
control program (e.g., the Great Lakes Fish and Wildlife
Restoration Act; 16 U.S.C. §§941-941h).
Sea lamprey control in Lake Champlain is coordinated by
the Lake Champlain Fish and Wildlife Management
Cooperative (LCFWMC), which was formed in 1973 to
coordinate efforts to mitigate the impacts of sea lampreys
on Lake Champlain’s fisheries. The LCFWMC is a
partnership of FWS, the New York State Department of
Environmental Conservation, and the Vermont Department
of Fish and Wildlife.
Control Methods
Managers use physical, chemical, and biological control

methods to reduce sea lamprey populations in the Great
Source: Brittney G. Borowiec et al., “Exploiting the Physiology of
Lakes and Lake Champlain. Physical control targets adult
Lampreys to Refine Methods of Control and Conservation,” Journal of
sea lampreys before they spawn in the early spring. These
Great Lakes Research, vol. 47 (2021), pp. S723-S741.
methods include barriers to prevent sea lampreys from
Sea lamprey populations in the Great Lakes and Lake
reaching spawning areas and traps to remove adults from
Champlain, however, complete their life cycle within
tributaries. Chemical control involves the application of
freshwater lakes and streams. After spawning, larval sea
lampricides or pheromones. The U.S. Environmental
lampreys typically remain in the streams where they
Protection Agency (EPA) must approve lampricides used in
hatched, referred to as nursery streams, for three to seven
the United States, which are restricted-use pesticides
years. Afterward, larvae metamorphose into juveniles and
manufactured for designated federal and state agencies.
enter the parasitic life stage, when they start feeding on
Lampricides are typically applied to streams and deltas to
other fish. Juveniles from the Great Lakes and Lake
target sea lamprey larvae at nurseries. Application of
Champlain populations migrate from their nursery streams
lampricides follows a procedure that includes conducting
to the deeper water of these lakes to feed on host fish. After
pre- and post-assessment of sea lampreys and nontarget
12-18 months of feeding, sea lampreys return to streams to
species and notifying residents who rely on treated lakes
develop into adults and spawn. Females can produce up to
and streams for water. Pheromones are typically used to
100,000 eggs when spawning and both sexes die shortly
lure adults and larvae into traps for disposal. Biological
after the spawning season.
control, used less commonly than other methods, involves
the release of sterile males during spawning to reduce sea
Population Trends
lampreys’ reproductive success.
Scientists use indirect methods to estimate sea lamprey
populations because of the difficulty of monitoring in deep
Selected Federal Funding for Control Efforts
water. Two commonly used measures are (1) wounding
Federal funding for sea lamprey control comes from several
rates on species such as lake trout and Atlantic salmon and
programs. Congress has on several occasions expanded the
(2) the number of individuals trapped in monitored “index”
scope and scale of programs to meet the goals of federal
streams. Sea lamprey populations have declined in the
control efforts for sea lampreys and other aquatic invasive
Great Lakes and Lake Champlain since the start of control
species. The Great Lakes Restoration Initiative (GLRI; 33
programs in the late 1950s and 1990, respectively. In the
U.S.C. §1268(c)(7)) provides funding, allocated by EPA, to
Great Lakes, populations have decreased by over 90% since
federal and state agencies for control of aquatic invasive
the 1960s. In Lake Champlain, populations have decreased
species, including sea lampreys. In 2021, Congress
by approximately 50% since the 2000s.
extended the annual authorization of appropriations for
GLRI and provided for an annual increase from $375
Federal Control Programs
million in FY2022 and ending at $475 million in FY2026.
Sea lamprey control and research are implemented by
Congress also has provided supplementary funds for sea
several federal agencies, nonfederal agencies, and other
lamprey control through annual appropriations to FWS’s
partners. Control and research efforts in the Great Lakes are
Fish and Aquatic Conservation program.
coordinated by the Great Lakes Fishery Commission
(GLFC). The GLFC is a binational entity with Canada
Considerations for Congress
established by the United States and Canadian Convention
Research from the GLFC and LCFWMC suggests control
on Great Lakes Fisheries in 1954 and codified by the Great
efforts must be ongoing to prevent the rebound of sea
Lakes Fishery Act of 1956 (16 U.S.C. §§931-939). In the
lamprey populations. Recent studies from Lake Champlain
United States, the GLFC’s control efforts are largely
also suggest sustained control requires that a large
implemented by the U.S. Fish and Wildlife Service (FWS),
proportion of the larval population receive effective
U.S. Army Corps of Engineers (USACE), and state fish and
treatment every year. Congress may consider evaluating the
wildlife agencies. The GLFC’s research activities are
conducted in cooperation with the U.S. Geological Survey;
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Federal Management of Sea Lampreys in the Great Lakes and Lake Champlain
impact of current efforts and the resources needed for long-
short-lived or are not likely to result in mortality. Congress
term control.
may consider conducting further oversight on EPA
procedures for assessing the effect of lampricides on
Some stakeholders have expressed concern over chemical
nontarget species, such as those listed under the
control of sea lamprey, especially the potential for negative
Endangered Species Act (16 U.S.C. §§1531-1544).
effects on nontarget species, such as the common
mudpuppy (Necturus maculosus). GLFC and LCFWMC
This product was coauthored by Christopher Field, former
scientists contend that lampricides have minimal effects on
CRS Analyst in Natural Resources.
non-lamprey species, but some other scientists note that
studies may not have addressed all potentially affected
Pervaze A. Sheikh, Specialist in Natural Resources Policy
species. Additionally, some scientists suggest any negative
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effects of chemical control on nontarget species are usually

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