Ann Arbor, MI - Scientists will release sterilized, spawning-phase male sea lampreys
in Michigan's Inland Waterway this May in hopes of employing another tool to combat
the invasive menace. The waterway - a nearly 40-mile chain of rivers and lakes in
the Northern Lower Peninsula - comprises the Pigeon, Sturgeon, and Maple rivers; rivers
that contain a landlocked sea lamprey population. This research, funded by the Great
Lakes Fishery Commission and Michigan Invasive Species Grant Program, will determine
whether sterilized male sea lampreys will compete with fertile males to spawn with
female lampreys, resulting in eggs that do not survive. The ultimate goal is to
use this "sterile-male-release-technique" as a method to reduce or possibly eliminate
sea lamprey reproduction - and thereby damage to fish caused by this invasive species - in
the Inland Waterway and Lake Huron.
When a sea lamprey has reached its spawning phase, its digestive system has ceased
to function and, thus, it is neither interested in nor capable of feeding on fish
(it is only interested in spawning). Thus, the release of sterilized, spawning-phase
male sea lampreys will not result in any fish loss due to sea lamprey predation.
The sea lamprey, an invasive species found in all five of the Great Lakes, attaches
to fish with a suction cup mouth and rasps through the fish's scales and skin with
a sharp tongue, feeding on the fish's blood and body fluids. Each sea lamprey is
capable of destroying up to 40 pounds of fish during its parasitic life stage. The
Great Lakes Fishery Commission coordinates a control program that has reduced sea
lamprey populations in the Great Lakes by about 90% since they first invaded in
the 1920s, saving nearly 100 million pounds of fish each year and contributing to
the $7 billion annual value of the fishery.
Since inception, the sea lamprey control program has relied on an integrated approach
that uses multiple control methods to achieve the best results. Sea lamprey are
primarily vulnerable at two points of its life-cycle: during the larval stage and
during the adult stage. Lampricides—selective chemicals that target larval lampreys—are
the workhorse of the control program and are applied in nearly 120 tributaries annually.
Barriers and traps are employed to block adults from reaching upstream spawning
habitat and remove them from the system before they reproduce.
Sea lampreys have been present in the Inland Waterway since at least the 1950s.
Starting in the 1960s, populations have been controlled with great success, primarily
with lampricides. Researchers believe the sterile-male-release technique may offer
an effective alternative to lampricides. The success of this alternate option is
predicated on the hypothesis that the number of adult sea lamprey spawning in the
Inland Waterway is quite low (likely fewer than 200, but still damaging) and many
may be landlocked, completing their lifecycle by feeding on fishes in Burt and Mullett
The sterile-male-release technique has been used before in the Great Lakes basin,
primarily on the enormous St. Marys River. The results were mixed. Researchers learned,
when using the sterile-male-release technique on the St. Marys, that one of the
keys to success is being able to massively overwhelm the population of fertile adults
with sterile males. Unfortunately, in the case of the St. Marys River, the population
of fertile adults was likely too high to be able to add enough sterile males to
the system to have the desired effect. As such, use of sterile males in the St.
Marys River was halted in 2011.
In the Inland Waterway, on the other hand, scientists believe the small population
of sea lampreys should be vulnerable to the sterile-male-release technique, particularly
because sea lamprey control agents should be able to easily outnumber the fertile
males with sterile males. If the technique proves to be successful in the Inland
Waterway, it will be a more cost effective option for control by reducing the number
of lampricide treatments needed going forward.
This spring, adult males will be captured at the Cheboygan Dam and sterilized at
the U.S. Geological Survey (USGS) Hammond Bay Biological Station in Millersburg,
Michigan. Starting in May 2017, the USGS, U.S. Fish and Wildlife Service, and Fisheries
and Oceans Canada will release 4,000 sterilized male sea lampreys, which no longer
feed on fish, into the Pigeon, Sturgeon and Maple Rivers. The research team plans
to release sterile males in a 40:1 ratio of sterile to fertile males, meaning a
female has a 1 in 40 chance of spawning with a fertile male. The objective is to
put enough sterile males into the system to outcompete the fertile males for mates.
If successful, the next scheduled lampricide treatment during 2020 will not be needed.
"The Inland Waterway offers an ideal location to evaluate an alternative sea lamprey
control method," said Dr. Nicholas Johnson, a USGS scientist and the lead researcher
for the project. "If successful, the sterile-male-release technique could be the
first step in eradicating sea lampreys from the waterway and would help protect
this valuable northern Michigan fishing and recreation area."
Johnson also explained that if successful, the technique would be the first time
that a control measure other than a dam has eliminated the need for lampricide treatments
in a Great Lake tributary.
"Maintaining an arsenal of alternative controls is the bench strength of the sea
lamprey control program," said David Ullrich, chair of the Great Lakes Fishery Commission.
"Doing so requires a commitment to research and innovation, and applying the sterile-male-release
technique to this unique population of sea lamprey is a clear example of both."
The Great Lakes Fishery Commission is an international organization established
by the United States and Canada through the 1954 Convention on Great Lakes Fisheries.
The Commission has the responsibility to support fisheries research, control the
invasive sea lamprey in the Great Lakes, and facilitate implementation of A Joint
Strategic Plan for Management of Great Lakes Fisheries, a provincial, state, and
tribal fisheries management agreement.