Northern Brook Lamprey

Ichthyomyzon fossor Reighard and Cummins, 1916

Ichthyomyzon fossor (Northern Brook Lamprey)
John Lyons, Wisconsin Department of Natural Resources

Petromyzontida (Lampreys)
Petromyzontidae (lampreys)
State Protection
Not Listed
Not listed or protected by New York State.
Federal Protection
Not Listed
State Conservation Status Rank
Imperiled in New York - Very vulnerable to disappearing from New York due to rarity or other factors; typically 6 to 20 populations or locations in New York, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines.
Global Conservation Status Rank
Apparently Secure globally - Uncommon in the world but not rare; usually widespread, but may be rare in some parts of its range; possibly some cause for long-term concern due to declines or other factors.


Did you know?

Northern Brook Lamprey (Ichthyomyzon fossor) is not parasitic like many other lampreys. When this species matures, it no longer feeds and dies soon after spawning.

State Ranking Justification

The Northern Brook Lamprey is rare in New York because of its limited distribution in the state. In 1983, the fish was confirmed in only one creek in western New York. It is currently confirmed in 12 brooks, creeks, and small rivers, but it is limited to two areas of the state, the Lake Erie watershed in western New York, and the Lake Champlain, Oswegatchie, and St. Lawrence River watersheds in northern New York (Carlson et al. 2016). Specimens that have been caught from a few other creeks and rivers have been thought to be this species, but they were difficult to identify and could not be confirmed. The fish may be discovered in additional creeks and small rivers with additional survey effort, however it is likely that it is indeed rare and that its distribution in the state is limited (Doug Carlson, pers. comm. 2009; Carlson 2001).

Long-term Trends

It appears that the Northern Brook Lamprey population has increased and the range expanded in New York. However, this may be due to increased Sea Lamprey survey efforts and improvements to survey methods over time. Neave et al. (2021) suggests that these improved survey methods may disguise declines in local populations.

Conservation and Management


Any activity which might lead to water contamination, siltation, warming of waterways, or the alteration of natural hydrology could directly and indirectly impact riparian habitats and Northern Brook Lamprey populations. Such threats might include roadway and agricultural runoff, industrial pollution, dams, bridge construction and maintenance, dredging, temporary dewatering, channelization, embankment, logging activities, and development near riparian habitats (NYS DEC 2005, Maitland et al. 2015, Lucus et al. 2021). Excessive sedimentation could be detrimental to spawning and larval rearing areas (Maitland et al. 2015, Fisheries and Oceans Canada 2016). In addition, siltation decreases the amount of sunlight that reaches aquatic plants (EPA 2005) and lowers the quality of habitats needed for a variety of aquatic species (NYS DEC 2005). Point source pollution, such as effluents from municipal and industrial facilities, contribute to the degradation and pollution of aquatic habitats (EPA 2022, NYS DEC 2005, Mahar and Landry 2013, Strayer et al. 2004). If pollution is significant, lampreys could be eliminated from a river system, especially in larval rearing areas because they are more susceptible to pollution than adults (Maitland et al. 2015).
Altering natural waterflow can degrade habitat and restrict species movement. Dams directly restrict or impede species movement, alter the flow of water, change the water temperature, and contribute to sedimentation (NYS DEC 2005, Zaidel et al. 2021). If water levels become low, a significant numbers of larval lamprey (ammocoete) probably die (Scott and Crossman 1973). Culverts may create barriers to upstream migrations for spawning. Sedimentation reduces the quality of stream bottoms for spawning habitat (Kart et al. 2005).
While modern day agricultural and silvicultural practices are an important aspect of the New York State economy, it is important to consider the effects on ecosystems and species. As these practices move closer to rivers, the natural riparian buffers are often removed. Riparian buffers maintain stream temperature and slow or prevent runoff of sediments from upland soil disturbances. Furthermore, they slow or reduce runoff from farm fields and pastures, such as contaminants from pesticides, fertilizers, manure, and sludge, into waterways (EPA 2005, NYS DEC 2005, Souza et al. 2020). Agricultural runoff, especially herbicides, may reduce or eliminate the food source for ammocoetes (Fisheries and Oceans Canada 2016). Excessive fertilizer use can lead to algal blooms that can be deadly to aquatic life and overgrazing of livestock in fields could introduce pathogens, oxygen-demanding organics and solids, and invasive species to aquatic ecosystems (EPA 2005). Eutrophication can also create anoxic conditions in spawning and larval rearing areas (Maitland et al. 2015).
Approximately 10% of introduced, non-native species could have an impact on the health of ecosystems (McCormick et al. 2009). Invasive plants tend to outcompete native plants and can change natural processes (NYS DEC 2005). There is an increased risk of runoff and erosion when these plants are along streams and rivers. Aquatic invasive plants and animals can alter the water chemistry, change the nutrient regime, or decrease the dissolved oxygen levels. Introduced fish can alter trophic relationships resulting in a change in native fish populations and decreased water quality (McCormick et al. 2009).
Climate change is another threat that is likely to have lasting effects on riverine systems. Irregular weather patterns can cause extreme drought, flooding, and temperature fluctuations. Heat waves are expected to be more intense (Frankson et al. 2022). The Northeast Region of the United States is expected to experience an increase in precipitation, more frequent storms, and higher than normal temperatures (EPA 2016, EPA 2022). Precipitation is expected to increase 10% to 15% in southern New York and 15 to 20% in northern New York by 2050 (Frankson et al. 2022). Extreme flooding can cause widespread erosion and runoff with added risk of contamination if flooding occurs at remediation sites, industrial sites, or wastewater treatment facilities (EPA 2016, EPA 2022). Temperature increases can significantly alter ecosystems. As water temperatures rise, the amount of dissolved oxygen decreases and evaporation increases, potentially lowering lake and stream levels (EPA 2022). Any combination of these events could change species distributions (EPA 2022) and those that cannot adapt or migrate may be extirpated from some areas (NYS DEC 2005).

Conservation Strategies and Management Practices

Protect water quality and reduce contamination and hydrological alteration (such as agricultural or road runoff, shoreline development, and damming) (NYS DEC 2005). Protect stream quality by maintaining both a riparian buffer that includes herbaceous and/or woody vegetation along the shoreline, and a significant forested buffer. These buffers reduce sediment and contaminant runoff (EPA 2005, NYS DEC 2005, Souza et al. 2020), provide shade, regulate temperature, and provide organic matter to animals (Hughes and Vadas 2021). Riparian zones with herbaceous and woody vegetation have high “indicator scores” for macroinvertebrates and fishes (Hughes and Vadas 2021).
Remove barriers to maintain or restore natural flow to waterways. Where removal is not possible, research alternatives that allow flow above and below a barrier.
In general, avoid stream crossings. If crossings are unavoidable, use Best Management Practices (BMP) to minimize disturbance to streams. Time periods of disturbance when water flow is low or normal and install stream-crossing structures at a right angle to the stream (Watershed Agricultural Council Forestry Program 2018). Temporary methods to reduce runoff include water bars, gravel, geotextile fabric, rubber belt deflectors, open top culverts, strawbales, silt fencing, control blankets, and straw wattles (Watershed Agricultural Council Forestry Program 2018). Restore the disturbed area with native species as soon as possible. Areas that have been logged may also need ruts to be smoothed to reduce surface runoff (Watershed Agricultural Council Forestry Program 2018). Hughes and Vadas (2021) suggest that Best Management Practices may need to be applied to entire stream lengths and catchments to fully restore an aquatic ecosystem. If this is not possible, restore or manage a larger area around the directly disturbed area.
In general, tailor agricultural management plans to local conditions (e.g., soils, slope, land use). Often these plans aim to reduce pollution and increase farm productivity, but incentives could also be used to encourage sustainable farming practices. Proper management typically reduces runoff by 20-90% (EPA 2005). Consider using Integrated Pest Management (IPM) as an alternative to pesticide use. If pesticides and fertilizers are used, they should only be applied when needed, in the proper amount, and timed appropriately. In addition, rotate livestock to avoid overgrazing and to allow for vegetation regrowth. If needed, provide alternative water sources and shade to keep animals out of sensitive areas (EPA 2005).
Invasive species management can be time consuming and costly. Reduce the likelihood of non-native species being introduced into waterways. Boat-washing stations at boat launches can reduce transport of invasive plants and animals to new waterbodies. Educate anglers about the risk of releasing unused baitfish. If vulnerable species are present, consider a baitfish ban. Mechanical removal of some invasive plants may be needed in some rivers and streams. The use of pesticides to remove invasives can have a negative effect on ecosystems (McCormick et al. 2009) and should be a last resort to control invasive species.
Climate change is a global challenge. However, there are local actions that can help mitigate extreme weather events. Industrial and municipal infrastructure should be improved or replaced to be more resilient to flooding events (EPA 2016, NYS Comptroller 2023). Some suggested actions include installing or improving pumps to remove floodwater from facilities and installing protective structures, such as floodwalls. Ensure that existing bridges, dams, levees, seawalls, retaining walls, and wind barriers are prepared for extreme weather (NYS Comptroller 2023). Decrease runoff and erosion severity by installing large culverts, planting vegetation along riverbanks, and protecting and restoring wetlands (EPA 2016, NYS Comptroller 2023).

Research Needs

Northern Brook Lamprey studies are difficult because the species can only be identified as adults, therefore research is restricted to early spring or late fall (Neave et al. 2021). A better understanding of this species biology and ecological needs will help develop good management strategies. Additional information is needed on the status of Northern Brook Lamprey in New York (Carlson 2001). Information about this species has been gained from studies conducted during Sea Lamprey control efforts in Vermont and other areas of the Great Lakes basin (Doug Carlson, pers. comm. 2009). However, additional information is still needed on trends and the significance of various threats (Carlson 2001, Kart et al. 2005, Fisheries and Oceans Canada 2016). More studies are needed regarding lamprey passages in areas where barriers cannot be removed, ways to reduce or remove Sea Lamprey without major implications on native lamprey populations, and how populations may respond to climate change.



In New York State, Northern Brook Lamprey inhabit streams and small rivers mostly in transition or middle reaches (Doug Carlson, pers. comm. 2009). They have somewhat specific habitat requirements. They seem to prefer clear, permanent, medium-sized streams with moderately warm temperatures (Becker 1983). For spawning, adults require clean, clear stream sections with alternating riffles and pools, where the substrate is usually gravel and stone (Pflieger 1997). Larvae (ammocoetes) drift downstream to quiet, clear water areas such as the slower parts of streams, pools, and the banks, where they dig U-shaped burrows in the sand or muddy sand bottom (Pflieger 1997; Smith 1985; Scott and Crossman 1973). The developing ammocoetes need these low-gradient, permanent waters with sand or silt substrate and organic debris as a place to reside while filter feeding (Pflieger 1997; Smith 1985). Transforming larvae and adults use burrows as a place to hide as well (Scott and Crossman 1973).

Associated Ecological Communities

  • Confined river* (guide)
    The aquatic community of relatively large, fast flowing sections of streams with a moderate to gentle gradient.

* probable association but not confirmed.


New York State Distribution

Northern Brook Lamprey occur in four watersheds in New York: Erie-Niagara, St. Lawrence, Oswegatchie, and Champlain. They are known from three creeks in western New York and nine brooks, creeks, and small rivers in northern New York. There are additional reports from western New York that lack voucher specimens (Carlson et al. 2016).

Global Distribution

Populations of Northern Brook Lamprey are found from the St. Lawrence River, Quebec, west through the Great Lakes and northern Mississippi River basins to the Red River (Hudson Bay basin), and southern Manitoba. Populations are localized in the Ohio River basin of northwestern Pennsylvania, western West Virginia, eastern Kentucky, northern and south-central Ohio, and northern Indiana. Disjunct populations occur in the Missouri River basin and Ozark Uplands, Missouri (Pflieger 1997). It is locally common (Page and Burr 1991). Within its range, New York is peripheral and disjunct (Carlson 2001). One population is known in Vermont, in the Lake Champlain basin (Kert et al. 2005). Recently the species was found in Iowa (Gelwicks et al. 2002).

Best Places to See

  • Redwater Brook (St. Lawrence County)

Identification Comments

Identifying Characteristics

The Northern Brook Lamprey is a small fish that resembles an eel. It reaches a maximum length of 7 inches (17 cm). It has an elongate body, 7 pairs of gill openings, no scales, a single nostril in front of the eyes, and a single dorsal (back) fin that is connected to the caudal (tail) fin. The body coloration is dark slate gray or brown on the back, silver below the gill region, and pale gray tinted with orange along the rest of the underside. There is often a pale line along the back. The fin is gray, yellow, or tan, with a light tan, bluish base. The lateral line organs are unpigmented. The fish is nonparasitic, and it has a small, round, sucker-like mouth that is usually narrower than the gill region. The mouth disc has weak, blunt teeth, all of which have only one point (cusp). The teeth are obvious only near the side of the mouth. They are very small or absent at the bottom and near the edge of the disc. There are usually 2 teeth immediately above the mouth cavity (but may be 1-3), 6-11 teeth immediately below the mouth cavity (which are extremely blunt and often obsolete), and 15-25 teeth in the circle around the mouth cavity. The Northern Brook Lamprey usually has 50-52 muscle bands (myomeres) between the last gill opening and the anus, but may have 47-56. Larval lamprey (ammocoetes) are blind and have a hood-like covering over their toothless mouths. Currently, based on morphological features, it is not possible to differentiate ammocoetes of the Northern Brook Lamprey and the species it is most similar to, the Silver Lamprey. It is not possible to differentiate ammocoetes from other lamprey species as well, based on morphology, because myomere counts overlap (Page and Burr 1991; Smith 1985). Attempts have been made to find a way to genetically differentiate ammocoetes according to species, however research conducted with mitochondrial DNA has been unable to to distinguish between Northern Brook Lamprey and Silver Lamprey ammocoetes (Mandrak et al. 2004), and research conducted with microsatellite genetic markers has had mixed results, including different results in different geographic areas (Filcek et al. 2005, Doug Carlson, pers. comm. 2009).

Characters Most Useful for Identification

Lamprey identification depends on coloration, type and pattern of teeth, and muscle band counts (Smith 1985).

Best Life Stage for Proper Identification

At this time, only adults are identifiable. Northern Brook Lamprey ammocoetes cannot be distinguished from Silver Lamprey based on morphological features or genetics.


Spawning occurs in late spring, in an area of a creek/small river with a gravel or stone substrate. Usually the water in this area is 8-18 inches deep (Scott and Crossman 1973). Adults use their suction-disc mouths to move stones to construct a nest cavity measuring 3-4 inches in diameter and up to 4 inches deep. During spawning, a male attaches to a female under a rock. The 1,000 - 1,350 eggs that are released settle into the nest cavity and hatch in about 12 days (Leach 1940). After hatching, the larvae (ammocoetes) drift downstream and create burrows in sand or silt substrate in clear, quieter water areas (Carlson 2001; Smith 1985; Scott and Crossman 1973). Ammocoetes have been used as bait, and it is likely that the lampreys are preyed upon by several stream fish (Scott and Crossman 1973). After spending 3-7 years as ammocoetes (Becker 1983; Scott and Crossman 1973), during which time they filter-feed, the ammocoetes transform into immature adults in late summer or fall, then into mature adults in winter. Transformers and adults use burrows for hiding. As the ammocoetes transform, the hood over the mouth disappears, and the digestive tract degenerates. The ammocoetes stop feeding as they transform into adults, and the adults never feed (Smith 1985; Scott and Crossman 1973). The adults live off their own body fat and muscle, and decrease in length and weight. They typically migrate upstream to spawn the May or June and die afterwards (Smith 1985; Becker 1983; Leach 1940).


Northern Brook Lampreys are nonparasitic. Ammocoetes are filter feeders and feed on microscopic animals and plants such as diatoms, protozoans, and desmids. They also eat organic matter such as detritus and pollen. They stop feeding as they transform into adults, and they never feed during the adult stage. As adults, they spawn and die afterwards (Smith 1985; Scott and Crossman 1973).

Best Time to See

The fish are present year-round. In Allen Brook, evidence of nesting/spawning was observed on May 14, 1999, when the water temperature was 55 F (Doug Carlson, pers. comm. 2009). This fits with data gathered in other parts of the species' range, where spawning has been found to occur in May or June when water temperatures reach 55-60 F (Becker 1983; Leach 1940).

  • Active
  • Reproducing

The time of year you would expect to find Northern Brook Lamprey active and reproducing in New York.

Similar Species

  • Ohio Lamprey (Ichthyomyzon bdellium)
    The Ohio Lamprey has one or more bicuspid teeth around the mouth cavity and a higher muscle band (myomere) count, 56-62, between the last gill opening and anus (Page and Burr 1991).
  • Mountain Brook Lamprey (Ichthyomyzon greeleyi) (guide)
    The Mountain Brook Lamprey has bicuspid teeth on the sides of the mouth cavity, black lateral line organs, no pale line on the back, and a higher muscle band (myomere) count, 57-60, between the last gill opening and anus (Page and Burr 1991).
  • Silver Lamprey (Ichthyomyzon unicuspis)
    The Silver Lamprey has an oral disc that is as wide or wider than the head, large sharp unicuspid disc teeth, black lateral line organs, and no pale line on the back (Page and Burr 1991). Northern Brook Lamprey is smaller than Silver Lamprey (Fisheries and Oceans Canada 2016). The two species are indistinguishable as ammocoetes.
  • American Brook Lamprey (Lethenteron appendix)
    The American Brook Lamprey has 2 dorsal fins and a higher muscle band (myomere) count, usually 67-73, between the last gill opening and anus (Page and Burr 1991).
  • Sea Lamprey (Petromyzon marinus)
    The Sea Lamprey is a large species (sometimes exceeding 2 feet in length), has 2 dorsal fins, has well-developed teeth arranged in radiating rows, and is the only lamprey in New York that is mottled in coloration (Smith 1985; Page and Burr 1991).

Northern Brook Lamprey Images


Northern Brook Lamprey
Ichthyomyzon fossor Reighard and Cummins, 1916

  • Kingdom Animalia
    • Phylum Craniata
      • Class Petromyzontida (Lampreys)
        • Order Petromyzontiformes (Lampreys)
          • Family Petromyzontidae (lampreys)

Additional Resources


Maitland, P.S., Renaud, C.B., Quintella, B.R., Close, D.A., and Docker, M.F. 2015. Conservation of native lampreys. In: Docker, M.F. (Ed.), Lampreys: Biology, Conservation and Control, Vol. 1, Springer, Dordrecht, pp. 375–428.

Marsden, J.E. and Siefkes, M.J., 2019. Control of invasive sea lamprey in the Great Lakes, Lake Champlain and Finger Lakes of New York, in: Docker, M.F. (Ed.), Lampreys: biology, conservation, and control. Vol. 2. Fish and Fisheries Series 38. Springer, New York, New York, USA, 411-479.

Fisheries and Oceans Canada. 2016. Management Plan for the Northern Brook Lamprey (Ichthyomyzon fossor) in Canada (Great Lakes – Upper St. Lawrence populations) [Proposed]. Species at Risk Act Management Plan Series. Fisheries and Oceans Canada, Ottawa. vi + 34 pp.

Becker, G. C. 1983. Fishes of Wisconsin. University of Wisconsin Press, Madison. 1,052 pp.

Carlson, Douglas M. 2001. Species accounts for the rare fishes of New York. New York State Department of Environmental Conservation, Division of Fish, Wildlife and Marine Resources. Bureau of Fisheries, Endangered Fish Project. 89pp.

Carlson, Douglas M., Robert A. Daniels, and Jeremy J. Wright. 2016. Atlas of Inland Fishes of New York. New York State Museum Record 7. The New York State Education Department and Department of Environmental Conservation. Albany, New York.

Filcek, Kristine B., Stacy A. Gilmore, Kim T. Scribner, and Michael L. Jones. 2005. Discriminating lamprey species using multilocus microsatellite genotypes. North American Journal of Fisheries Management 25:502-509.

Gelwicks, G., J. Heitke, and G. Simmons. 2002. Contemporary fish survey. Iowa Department of Natural Resources, Manchester, Iowa.

Kart, J., R. Regan, S.R. Darling, C. Alexander, K. Cox, M. Ferguson, S. Parren, K. Royar, B. Popp (eds.). 2005. Vermont's Wildlife Action Plan. Vermont Fish and Wildlife Department. Waterbury, Vermont. Available:

Leach, W. J. 1940. Occurrences and life history of the northern brook lamprey, Ichthyomyzon fossor, in Indiana. Copeia (1): 21-34.

Lucas M.C., J.B. Hume, P.R. Almeida, K. Aronsuu, E. Habit, S. Silva, C.J. Wang, and B. Zampatti. 2021. Emerging conservation initiatives for lampreys: research challenges and opportunities. Journal of Great Lakes Research. Vol 47, supplement 1. pp. S690-S703.

Mandrak, N.E., M.F. Docker, D.D. Heath. 2004. Native Ichthyomyzon lampreys of the Great Lakes Basin: Development of genetic markers and a morphological key to ammocoetes. Final report submitted to the Great Lakes Fishery Commission. 114 pp.

Neave, F.B., Booth, R.M.W., Philipps, R.R., Keffer, D.A., Bravener, and G.A., Coombs, N. 2021. Changes in native lamprey populations in the Great Lakes since the onset of sea lamprey (Petromyzon marinus) control. J. Great Lakes Res. 47, S378–S387.

New York Natural Heritage Program. 2023. New York Natural Heritage Program Databases. Albany, NY.

Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes: North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.

Pflieger, W. L. 1997a. The fishes of Missouri. Revised edition. Missouri Department of Conservation, Jefferson City. vi + 372 pp.

Scott, W. B., and E. J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada, Bulletin 184. 966 pp.

Smith, C.L. 1985. The Inland Fishes of New York State. New York State Department of Environmental Conservation. Albany, NY. 522pp.


About This Guide

This guide was authored by: Shaw, Hollie Y.

Information for this guide was last updated on: September 28, 2023

Please cite this page as:
New York Natural Heritage Program. 2023. Online Conservation Guide for Ichthyomyzon fossor. Available from: Accessed December 8, 2023.