Ichthyomyzon fossor John Lyons, Wisconsin Department of Natural Resources

Ichthyomyzon fossor
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?

Lampreys are ancient fish, which have persisted almost unchanged for about 250 million years. Interestingly, they were the first vertebrates. Ichthyomyzon may be the most primitive genus of lampreys (Moen 2002; Smith 1985).

State Ranking Justification

The northern brook lamprey is rare in New York because of its limited distribution in the state. When the state rarity rank of S1 was assigned in 1983, the fish was confirmed in only one creek in western New York. Now it is confirmed in 10 brooks, creeks, and small rivers in New York, but it is limited to two areas of the state, the Lake Erie watershed in western New York, and the Lake Champlain and St. Lawrence River watersheds in northern New York (New York Natural Heritage Program 2008). Specimens that have been caught from a few other creeks and rivers in the state have been thought to be this species, but they were difficult to identify and could not be confirmed. Although additional information on the status of the northern brook lamprey in New York State is needed, and although the fish may be discovered in additional creeks and small rivers with additional survey effort, it is likely that it is indeed rare and that its distribution in the state is limited (Doug Carlson, pers. comm. 2009; Carlson 2001).

Conservation and Management


Additional research is needed on threats and their significance (Kart et al. 2005). 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). The application of lampricides to control parasitic sea lamprey populations in Lake Champlain may be a threat, although numbers of northern brook lampreys captured before and after lampricide treatments in the Great Chazy River, a tributary of Lake Champlain, showed no permanent effects. There were 8 dead northern brook lamprey present in a sample of 23,394 dead lampreys shortly after treatment, comprising 0.84% of the total. It was estimated that 197 northern brook lamprey died as a result of the treatment, if the proportion held (New York Natural Heritage Program 2008; Carlson 2001).

Conservation Strategies and Management Practices

Habitat protection is important for the northern brook lamprey. The fish is senstitive to environmental degradation, and seems to prefer undisturbed habitat and clear water. Watershed management practices that reduce erosion and pollution, and thus maintain high water quality, are beneficial (Kart et al. 2005; Moen 2002; Becker 1983). Barriers to movement such as culverts and dams should be addressed to ensure adult fish can migrate upstream to spawn and to ensure habitat connectivity (Kart et al. 2005). Lampricides, which are intended to control parasitic sea lamprey populations, usually do not affect most fish populations but are toxic to all lampreys. The distribution of northern brook lampreys and parasitic sea lampreys overlap in some areas, but northern brook lampreys can also be found in upstream areas that are not suitable for sea lampreys. Consequently, lampricides should be applied with discretion and, whenever possible, should not be applied in northern brook lamprey habitat (Kart et al. 2005; Moen 2002; Becker 1983). In Vermont, traps are being used instead of lampricides to control parasitic sea lampreys in streams in which northern brook lampreys are also known to be present (Kart et al. 2005).

Research Needs

Additional information is needed on the status of the northern brook lamprey in streams in New York (Carlson 2001). Information about the fish 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 threats and their significance, as well as habitat changes in areas where the fish is known to be present (Kart et al. 2005; Carlson 2001).



In New York State, northern brook lampreys 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 lampreys are known from 3 creeks in western New York and 7 brooks, creeks, and small rivers in northern New York. The western creeks are located in Erie County and are part of the Lake Erie watershed. The northern waterbodies are located in Clinton, Franklin, and St. Lawrence Counties and are part of the Lake Champlain and St. Lawrence River watersheds (New York Natural Heritage Program 2008).

Global Distribution

Populations of northern brook lampreys are found from the St. Lawrence River, Quebec, west through the Great Lakes and northern Mississippi River basins to the Red River (Hudson Baybasin), 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 always 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 find a way 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 (Doug Carlson, pers. comm. 2009; Filcek et al. 2005).

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

The adult stage is the only life stage at which the northern brook lamprey can be distinguished from the silver lamprey based on morphological features. It is often not possible to differentiate larvae (ammocoetes) of the northern brook lamprey from other lamprey species based on morphological features (Smith 1985).


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 and have a hood-like covering over their toothless mouths, 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 following their transformation, and die afterwards (Smith 1985; Becker 1983; Leach 1940).


Northern brook lampreys are nonparasitic. Larval lampreys (ammocoestes) 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)
    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).
  • 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


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

Carlson, Douglas M. 1998. 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. 95pp.

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.

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.

Hardisty, M. W. and I. C. Potter, eds. 1971. The Biology of Lampreys. Academic Press, London and New York. pp. 1-65.

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: http://www.vtfishandwildlife.com

Lanteigne, J. 1992. Status of the northern brook lamprey, Ichthyomyzon fossor, in Canada. Canadian Field-Naturalist 106:7-13.

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

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.

Moen, Sharon. 2002. Lake Superior's native lampreys. Seiche Newsletter. March 2002.

New York Natural Heritage Program. 2008. Biotics Database. Albany, NY.

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.

Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 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.

Werner, R.G. 1980. Freshwater fishes of New York State. N.Y.: Syracuse University Press. 186 pp.

Wilson, F. W. 1955. Lampreys in the Lake Champlain basin. American Midland Naturalist 54(1):168-172.


About This Guide

Information for this guide was last updated on: March 5, 2009

Please cite this page as:
New York Natural Heritage Program. 2023. Online Conservation Guide for Ichthyomyzon fossor. Available from: https://guides.nynhp.org/northern-brook-lamprey/. Accessed March 23, 2023.

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