Sea Lamprey Control
The Great Lakes are a valuable resource shared by Canada and the United States.
The Great Lakes fishery generates up to $4 billion for the region annually, offering
recreational angling opportunities for five million people and providing 75,000 jobs.
The health of the Great Lakes fishery is under constant threat from habitat loss,
pollution and non-native nuisance species, including the sea lamprey. Based at the
Sea Lamprey Control Centre in Sault Ste. Marie, Ontario, Fisheries and Oceans Canada
(DFO) plays a critical role in minimizing sea lamprey population levels in the Great Lakes.
Sea lampreys are primitive fish native to the Atlantic Ocean. Sea lampreys were first
observed in the Great Lakes in the 1830's. It is widely believed that they entered and
spread throughout the Great Lakes via man-made shipping canals. In the Great Lakes,
they have no commercial value and other fish do not normally feed on them.
Sea lampreys are parasitic pests. They attach to fish with their suction cup mouth
and teeth, and use their tongue to rasp through a fish's scales and skin so they can
feed on its blood and body fluids. A single sea lamprey will destroy up to 18 kilograms
of fish during its adult lifetime. Sea lampreys are so destructive that, under some
conditions, only one out of every seven fish attacked will survive.
In the 1940's and 50's, sea lamprey populations exploded in the upper Great Lakes as
there were no effective control methods. This contributed significantly to the collapse
of valuable fish populations, such as lake trout and whitefish, which were the economic
mainstay of a vibrant Great Lakes fishery.
To facilitate coordinated, binational fisheries management, the governments of Canada
and the United States signed the 1954 Convention on Great Lakes Fisheries
created the Great Lakes Fishery Commission. This bilateral agreement affirms the need for
the two nations to collaborate on the protection and perpetuation of the Great Lakes
fisheries resources. In Canada, DFO
is the primary agent of the Great Lakes Fishery Commission. In the United States, the U.S.
Fish and Wildlife Service is the primary agent of the Commission, with significant support
from the U.S. Geological Survey and the U.S. Department of State. Scientists and fisheries
managers from both countries meet regularly to discuss new developments in research and
up-to-date stock estimates.
Understanding the sea lamprey's life cycle helps scientists develop effective control measures.
Adult sea lampreys swim upstream to spawn and then die. Fertilized eggs hatch into small worm-like
larvae that burrow into stream bottoms and feed on debris and algae for an average of three to six
years before they transform into the parasitic adult. The adults migrate into the Great Lakes where
they spend 12 to 20 months feeding on fish. The complete life cycle, from egg to adult, takes an
average of five to eight years to complete.
Fisheries and Oceans Canada undertakes sea lamprey control on Canadian streams and rivers
in the Great Lakes. In cooperation with the U.S. Fish and Wildlife Service, extensive work is also
carried out in U.S. waterways leading to the Great Lakes. Currently, the primary method to control
sea lampreys is the application of selective lampricides
that kill sea lamprey larvae in their nursery streams with little or no impact on other fish or wildlife. Despite the success of lampricide
treatments, it is a costly control method and DFO
would prefer to reduce its use by relying more heavily on alternate control methods.
The sterile-male-release technique
aims to reduce the success of sea lamprey
spawning. Each year, male sea lampreys are collected and sterilized during their spawning
runs. When they are released back into streams, the sterile males compete with normal males
for spawning females, resulting in reduced fertilization of eggs. Since they are caught during
spawning runs rather than during the parasitic phase, sterilized males do not prey on fish
when they are released back into the spawning streams.
Barriers have been constructed to block the upstream migration of spawning sea lampreys,
while allowing other fish to pass with minimal disruption. Various types of barriers have eliminated
lampricide treatment on some streams and reduced the area of the stream requiring lampricide
treatment on others.
A comprehensive assessment program
allows biologists to better understand
the ecology and population dynamics of the sea lamprey at all stages of its life cycle. The
information gathered allows DFO
to track long-term trends in lamprey populations, to monitor the effectiveness of the
lampricide control program and to identify alternative ways of controlling sea lamprey
populations. The ultimate purpose of collecting and analyzing the data is to develop and
implement the most efficient and effective control program at the lowest cost and with
the least possible negative effect on the environment.
The assessment program monitors abundance of larval sea lampreys
Lakes streams to determine where lampricide treatments should occur, when treatments
are required and how effective past treatments were. Measuring the size and age of the
larvae collected provides biologists with information about how well the populations grow
and survive in each stream. New technologies, such as geographic positioning systems
(GPS) and geographic information systems (GIS), are being used to map the exact
distribution of larvae and to target control efforts.
Through a cooperative program, charter boats and commercial fishers provide government
agencies with data on the occurrence of parasitic-phase sea lampreys
in the open
waters of the Great Lakes. Fisheries and Oceans Canada uses these data to predict the
extent of damage caused to fish communities by sea lamprey parasitism.
Biologists monitor adult sea lamprey spawning migrations in spring and early summer to
estimate the number of spawning sea lampreys
in selected Great Lakes streams.
Sea lamprey traps, often used in association with barriers, are fished to catch adult
lampreys as they travel upstream to spawn. These assessment data provide an accurate
measure of lakewide sea lamprey populations and are used to assess the overall success
of the sea lamprey control program. Male lampreys caught in the traps are used for the
sterile-male-release technique; most females are used for continuing research.
Sea lamprey control in the Great Lakes has been tremendously successful. Ongoing
control efforts have resulted in a 90 percent reduction of sea lamprey populations in
most areas, creating improved conditions for fish survival and spawning. Although it is
impossible to completely rid the Great Lakes of sea lampreys, through continued
cooperation and support, their populations can be kept at levels that lessen their
impact to the fishery.
For more information on sea lamprey control in the Great Lakes, contact the Sea
Lamprey Control Centre at 1 Canal Drive, Sault Ste. Marie, ON, P6A 6W4; by phone
at (705) 941-3000; or visit our regional website