Department of Environmental Conservation

D E C banner

Sea Lamprey Control

Lake Champlain Sea Lamprey Control

NYS DEC logo
Vermont Fish and Wildlife logo
US Fish & Wildlife Service logo

Why Control Sea Lamprey?

Atlantic salmon with wounds and scars from lamprey attacks. The federal and state governments, the agencies that manage Lake Champlain, the various organizations that are concerned with Lake Champlain and the people that live in the Lake Champlain Basin generally agree that it would be irresponsible not to control the sea lamprey population.

Prior to the 1800s native Atlantic salmon and lake trout were abundant in Lake Champlain. Early explorers and settlers reported salmon runs in the tributaries that were so abundant that "salmon were harvested by the wagon load with pitchforks." While not so graphic, historical accounts of large and plentiful lake trout were reported as well. However, by the mid 1800s over fishing, pollution and damming of tributaries had eliminated native salmon from Lake Champlain, and lake trout disappeared from the lake by 1900.

During the late 1800s and early 1900s numerous attempts were made to restock trout and salmon, but all failed. In the late 1950s and 1960s New York State began experimental stockings of lake trout and salmon with some limited success.

Lake trout with two lampreys attached.

In 1973, the New York State Department of Environmental Conservation, the Vermont Department of Fish and Wildlife and the United States Fish and Wildlife Service formed the Lake Champlain Fish and Wildlife Management Cooperative to establish a lake-wide salmon and lake trout restoration program.

By 1985, it became clear that the goal of restoring the salmon and lake trout fishery were unattainable due to the impacts of sea lamprey. The cooperative began an integrated control program to reduce the sea lamprey population in Lake Champlain to an acceptable level.

Sea Lamprey Control Program

small map showing the different methods employed to control Lake Champlain sea lamprey with different color codes
Click on the map to see a larger map

An 8-year experimental sea lamprey control program was developed and underwent an extensive regulatory review process. An Environmental Impact Statement (EIS) was developed pursuant to the National Environmental Policy Act and permit applications were reviewed by environmental and health agencies in New York and Vermont. The Final EIS determined to proceed with the proposed experimental sea lamprey control program and the state regulatory agencies issued the necessary permits to implement it.

Under the experimental sea lamprey control program, thirteen (13) streams and five (5) deltas were treated between 1990 and 1997. While the results of the experimental program were being reviewed, a limited, three year interim sea lamprey control program was undertaken from 1998 to 2000 in which eight (8) streams (but no deltas) were treated.

After reviewing the effectiveness of the experimental control program, a Supplemental Environmental Impact Statement (SEIS) was developed which identified an extensive, long term, integrated control program as the desired approach to sea lamprey control in Lake Champlain.

This long term sea lamprey control program is an adaptable program that initially targets 20 Lake Champlain stream systems for possible sea lamprey control activities. It expands on both the control effort and the techniques utilized in the experimental control program. The long term control plan requires the development of sea lamprey control strategies specific to each location. This ensures effective control of sea lamprey populations with minimal environmental impacts.

In 2002, the current long-term control program was implemented utilizing chemical treatments, trapping, physical barriers and other methods of control. The sea lamprey control program is not attempting to eliminate the sea lamprey from Lake Champlain, but rather to reduce the impacts of sea lamprey on the lake's fishery and restore balance to the ecosystem.

Barrier Dams

Barriers prevent sea lamprey from reaching spawning areas in the tributaries. Sea lampreys are prevented from spawning or are forced to lay their eggs in habitat less suitable or unsuitable for hatching of eggs and growth of larval sea lamprey. Where conditions are favorable, barriers are an effective means of sea lamprey control, cutting off large amounts of habitat suitable for spawning from the adult sea lamprey.

Sea lamprey barrier dam on a stream.

A variety of barrier types are used, with different means of preventing adult sea lamprey from proceeding upstream. Vertical-drop barriers are the most widely used. Water velocity barriers and electronic barriers are under development. In many streams, provisions are made to accommodate migratory fish passage while preventing upstream passage of sea lamprey adults.

While many dams present in the Lake Champlain watershed function as barriers to sea lamprey the following dams have been repaired for this specific purpose:

  • The Frog Farm Dam on the Great Chazy River in New York, which resulted in reducing the amount of sea lamprey spawning habitat by 12 miles.
  • The deteriorating Scott Pond Dam on Lewis Creek in Vermont was rebuilt as a barrier to maintain the upstream limit of sea lamprey spawning migrations, and to prevent sea lampreys from potentially infesting over 15 additional miles of stream habitat.

Studies looked at the possibility of constructing sea lamprey barriers on several Lake Champlain tributaries. In Vermont, feasibility studies on Stone Bridge Brook and Lewis Creek (7 miles downstream of Scott Dam) indicated that at the time of the studies, the barriers were environmentally unacceptable or cost prohibitive. New York streams being investigated for the potential construction of sea lamprey barriers are the Salmon River, Little Ausable River, and Putnam Creek.

A seasonally installed, temporary barrier was built on Beaver Brook in Westport, NY in 2009. This trap was so successful in blocking access to spawning areas upstream that the regular treatment of Beaver Brook, scheduled in 2010, was canceled. While not all barriers are capable of replacing the need for chemical treatments, smaller rivers like this are great examples of how our Integrated Pest Management approach is being successful on several fronts.

Potential barrier sites continue to be revisited to determine their suitability for a sea lamprey barrier as design technologies, site access and landowner cooperation may change over time. Additional investigations have been conducted for sea lamprey barriers on the Poultney and Hubbardton Rivers and on the Pike River.

Morpion Stream Lamprey Barrier

Until recently Quebec's Morpion Stream, a tributary to Vermont's Pike Creek, was the single largest source of lamprey to Lake Champlain. The Morpion Stream Lamprey Removable Barrier was completed in 2013 and began operating in the spring of 2014. The barrier blocks adult sea lamprey from accessing miles of spawning grounds during the spring.

The barrier, which includes an integrated trap, is installed in the spring, prior to adult lamprey retuning to spawn, and removed from the stream after the spawning season. It allows the passage of non-target species upstream of the barrier while trapping lamprey below the barrier. The trapped lamprey are removed and euthanized. Removing migrating adult sea lamprey below the barrier prevents them from moving to other streams and spawning in them.

The full effect of a sea lamprey barrier will not be realized until after 2018 because there are larval sea lamprey already in the tributary of upstream of the barrier that may not transform and move into the lake to become parasites until then.


Temporary lamprey trap in a small stream.

Traps are used to capture adult sea lamprey before they can spawn. Adult sea lamprey are trapped in tributaries during upstream spawning migration. Traps are strategically placed where migrating adults concentrate in the stream channel, usually along the face of a weir, dam or waterfall. Portable traps are rigid box traps with a cone-shaped (fyke) net entrance. Sometimes wing extensions are used to block the channel and/or steer the sea lamprey to the trap. Sea lamprey that enter the trap are unable to find an exit and are removed at regular intervals.

Permanent lamprey trap built into a dam on a river.

Sea lamprey traps are particularly useful in conjunction with sea lamprey barrier structures and in constricted stream channels where adults concentrate. Trapping at barriers limits the adult sea lamprey from moving to alternative streams where they may successfully spawn. Trapping is labor-intensive, and traps must be maintained for the duration of the spawning run.

Trapping is used as a supplemental control method except where the physical stream conditions make trapping an effective primary technique or where other control techniques are not feasible. Upstream escape of a small number of adults could repopulate available nursery habitat resulting in little or no reduction of the sea lamprey produced in the stream. The smallest sea lamprey spawning streams with small numbers of spawning sea lamprey and high trap efficiency provide the most potential for control by adult trapping alone.

Traps are operated during the spring spawning season, usually from shortly after ice out to late June. Traps are operated on the following waters:

  • New York
    • Great Chazy River
    • Rea Brook
    • Beaver Brook
    • Mullen Brook
  • Vermont
    • Sunderland Brook
    • Indian Brook
    • Pond Brook
    • Trout Brook
    • Stonebridge Brook
    • Malletts Creek
    • Potash Brook

Lampricides and Treatments

The most significant and effective form of control has been the treatment of streams and deltas with lampricides - TFM in tributaries and Bayluscide on deltas. The lampricides target the larval sea lamprey, killing them before they can transform into their parasitic adult form. Since the larval sea lamprey typically reside in streams or deltas for 4 years, lampricide treatments need only occur every 4 years in a specific water.


The chemical compound 3-trifluoromethyl-4-nitrophenol, better known as TFM, is remarkably effective for controlling sea lampreys without significantly impacting other species. TFM was developed as a lampricide in the 1950's following evaluations of over 6,000 chemicals for this purpose.

TFM has been successfully used in the Great Lakes since 1958 to control sea lamprey and is considered one of the most target specific pesticides in use today. It is relatively non-toxic to fish other than lamprey at the levels used in control treatments. Some non-targeted fish and other aquatic organisms may be killed in TFM treatments, but numerous studies have shown that the effects on non-targeted species are minor and do not have long term effects on the populations of non-targeted species.

TFM formulations are approved by the US Environmental Protection Agency (EPA) to be used for sea lamprey control in the Great Lakes, Finger Lakes and Lake Champlain watersheds. The treatment procedures used in Lake Champlain are consistent with the use described on the label and with Great Lakes Fishery Commission standard operating procedures.

Decades of laboratory tests and experience from thousands of stream treatments have demonstrated that at the dose needed to control sea lampreys, TFM is nontoxic or has minimal effects on aquatic plants, other fish, and wildlife. Studies have also shown TFM to be nontoxic to humans and other mammals. TFM does not accumulate in the tissue of aquatic organisms and it breaks down in a matter of days. In the Great Lakes, long term studies have shown no traces of TFM in fish, even in cases where several treatments had been made in tributaries to the lakes in which the fish were caught.

Stream Treatments

Liquid TFM being applied to a stream during lamprey control treatment.

During the treatment of a stream (or river) TFM is applied in closely monitored and precisely measured amounts to target larval sea lamprey. The amount of TFM applied is based on the chemical and physical characteristics of the stream - such as flows, pH, alkalinity, etc. - at the time of the treatment, so as to maintain a steady but very low concentration of TFM in the stream. The application of the TFM is monitored constantly throughout the treatment period, and adjusted as needed based on the chemical and physical characteristics of the water and the concentrations of TFM in the water which are also monitored.

A great deal of effort is undertaken before, during and after a TFM treatment to ensure that the treatment is effective, to prevent effects on human health and to minimize environmental impacts.

Activities Before Treatment

  • Assess through sampling the presence and abundance of larval sea lamprey to determine whether a treatment is warranted. (1 year before treatment)
  • Notify residents and landowners along the stream to be treated about the treatment and ask if they need alternate water supplies for humans or livestock. (4-6 months before treatment)
  • Notify landowners along the stream of impending treatment. (2 weeks before treatment)
  • Provide fencing to keep livestock out of treatment waters and provide alternate water source if needed. (1 week before treatment)
  • Activate toll free "treatment hotline" that provides updated treatment schedules and water use advisory information. This number is included in all published notifications, press releases, web pages and radio broadcasts. (1 week before treatment)
  • Walk length of stream to be sure there are no dams or other obstructions that could compromise the effectiveness of the treatment (Few days before treatment)
  • Publish treatment schedule in area newspapers, DEC web site and other media (Few days before treatment)
  • Begin regular testing of water chemistry and monitoring of stream flows at a variety of times and locations to obtain information to determine the amount of TFM to be applied. (Few days before treatment)
  • Directly notify households that use water from the stream and provide them with bottled water. (1 day before treatment)
  • Post water-use advisories at access sites to the stream and lake shore near the mouth of stream. (1 day before treatment)
  • Broadcast water-use advisories on area radio stations. (1 day before treatment)
  • Perform a toxicity test to refine an estimate of the treatment concentration required to conduct a safe but effective treatment. (1 day before treatment)

Activities During Treatment

  • Conduct chemical concentration monitoring every half hour to hour, and adjust application rates accordingly. (Water samples are taken at a variety of locations as the treatment progresses, and the samples are brought to a mobile lab and analyzed on-site.)
  • Follow chemical plume as it moves downstream to verify all lamprey habitat is being effectively treated, check for unexpected impacts on non-target species, and adjust application rates accordingly. (It should be noted that unexpected impacts on non-target species have never occurred during a treatment on Lake Champlain)

Activities After Treatment

  • Assess mortality of larval sea lamprey and non-target species. (1 day after treatment)
  • Monitor concentrations of TFM in streams until such time that water advisories along the stream can be lifted. Notify area radio stations and update information on treatment hotline when water advisory is lifted. Notify stream water users directly.
  • Monitor lake water concentrations of dilute lampricides by taking samples from multiple locations and depths in the lake shore water advisory zone. Notify area radio stations and update information on treatment hotline when water advisory is lifted. Notify lake shore water users directly.


Bayluscide is the product name of a lampricide that is used to treat the deltas where larval lamprey reside. The active ingredient in Bayluscide is niclosamide. The product is in a granular form which allows it to sink to the bottom where it releases the niclosamide into the waters close to the burrows of the larval sea lamprey.

Delta Treatments

Bayluscide granules being distributed from a boat during lamprey control treatment on a delta.

The difference between a delta treatment and a stream treatment is the type of chemical applied, form of the chemical applied, and the method of application. Bayluscide is a granular material that is applied through a mechanical spreader mounted on a platform on the back of a boat. The boat moves back and forth on the waters above the delta using a grid of buoys to ensure that the Bayluscide is applied evenly across all areas to be treated. Bayluscide is applied at a certain number of pounds per acre of area treated.

Besides the method of application there are a few differences in the activities undertaken before, during and after a delta treatment and those described in the stream treatment. Prior to treatment, a grid of buoys is set in the treated area to ensure a complete and even distribution of the Bayluscide. The buoys are removed once the treatment has been completed.

Water chemistry and chemical concentrations are not routinely monitored because the lampricide is released into the waters just above the bottom.

The level of wave action is closely monitored. Treatment is suspended during high wave periods because it can affect the safety of boat crews and their ability to apply the bayluscide evenly across the treatment area.

Otherwise all of the activities described under the stream treatments, are undertaken before, during, and after the delta treatments to ensure that the treatment is effective, to prevent effects on human health, and to minimize environmental impacts.

Combined Applications

A 1% solution of Niclosamide, when added to TFM, reduces the volume of TFM needed by about half. The same lethal effects to lamprey can be achieved using half of the amount of TFM. Not only does this result in substantial savings in the costs of treatments but it also means a reduction of the amount of pesticide placed into the waters of the Lake Champlain Watershed.

In 2011, the Boquet River in Willsboro, NY was successfully treated with a TFM-Niclosamide combination. This was the first combination treatment done in the Lake Champlain Basin. Since then a number tributaries have been treated using the combination of the two lampricides.

Integrated Sea Lamprey Control

Scientists and fish managers have considered, and continue to consider, other methods to reduce sea lamprey impacts. These include improvements in survey methods, the use of barriers, and the stocking of lamprey resistant strains of fish.

The Cooperative will continue to use an integrated approach to control sea lamprey because no single technique can provide maximum effectiveness throughout the Lake Champlain watershed. Ecological, social, political, and financial concerns all factor into sea lamprey control; the more techniques available, the better the ability to adapt and effectively address various conditions of specific situations. The Cooperative will also continue to explore new means for effectively controlling sea lamprey. The use of a variety of methods provides the means to reduce the reliance on chemical pesticides - but likely will not eliminate it.


Electroshock sampling for larval lamprey in a stream.

Fish sampling programs, salmon returns to fish ladders, angler surveys and sampling of larval sea lamprey are used to measure the effectiveness of the control program. The control program may be expanded to other streams and delta areas if significant sea lamprey populations develop in them.

Assessments of sea lamprey populations are made before any control measures are undertaken and afterwards to assist in determining the effectiveness of the controls. Field staff, using a variety of capture methods, sample both adult and larval sea lamprey from streams and deltas to determine the presence, density and stage of sea lamprey populations.

This information is used to determine which streams or deltas are in need of control measures, if and when a stream or delta needs to be treated and which control measure will be used. Also assessment of larval sea lamprey populations in deltas allows managers to determine where to focus treatments, providing the most effective treatment while expending less effort and money.

Effects of the Control Program

Evaluation of the eight year experimental sea lamprey control program that took place in Lake Champlain in the 1990s documented significant benefits for fish and anglers. These benefits included decreased wounding and scarring rates, and increased survival rates of lake trout and landlocked salmon. Angler creel surveys showed that more and substantially bigger trout and salmon were caught as a result of the treatments.

Sea lamprey control also generates a favorable economic benefit/cost ratio as angling opportunities increase. According to Benefit Cost Analysis of the Eight-year Experimental Sea Lamprey Control Program on Lake Champlain, a study conducted by Alphonse H. Gilbert, a researcher from the University of Vermont, sea lamprey control generated benefits of approximately $29.4 million with costs of about $8.4 million, a benefit to cost ratio of 3.5 to 1. These benefits were the result of the increased number of boaters and anglers spending longer periods of time in the Lake Champlain area.

Graph outlining success of Sea Lamprey control mechanisms from 2003-2010

Annually collected data show that the number of sea lamprey wounds on lake trout and landlocked Atlantic salmon began declining 2007. Sampling in the fall of 2011 found wounding rates have continued to be kept low and near our management targets. Despite not reaching that goal yet, the sustained suppression of wounding rates in recent years has yielded a positive response in size and number of both species in the lake. Continuation of current sea lamprey control efforts and ongoing innovations in treatment strategies and new barriers are expected to lead to further improvements in the trout and salmon fishery of Lake Champlain as well as the entire aquatic community.