New York Natural Heritage Program
Northern Brook Lamprey
Ichthyomyzon fossor Reighard and Cummins, 1916

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).

Behavior [-]
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).

Diet [-]
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).
Northern Brook Lamprey Images
click to enlarge
The 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 (blue shading) and reproducing (orange shading) in New York.
Similar Species
  • 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).
  • American Brook Lamprey (Lampetra 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).
  • 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).
  • 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).
  • 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).