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Northern brook lamprey

Ichthyomyzon fossor

What do they look like?

Northern brook lamprey appear very similar throughout their life cycle. This species has a continuous dorsal fin that may or may not be divided by a small notch and is connected to a round, short caudal fin. Individuals are grayish brown dorsally with a pale median line down the back and a lighter ventral side, with the posterior end darker in color (almost black). There are a few differences between ammocoetes and adults: ammocoetes have neither eyes nor a sucking disk mouth (they have a hooded mouth instead). Adults have eyes and disk-shaped mouths with small, poorly developed teeth. Once adults are of breeding age it is possible to differentiate between the sexes (males have a urogenital papilla and females have an enlarged post-anal fold). ("Ichthyomyzon fossor: Northern Brook Lamprey", 2012)

  • Sexual Dimorphism
  • female larger
  • Average mass
    2.2 g
    0.08 oz
  • Average length
    16 cm
    6.30 in

Where do they live?

Northern brook lamprey are found in many areas of the midwestern and northeastern United States, including the Mississippi River drainage in Wisconsin, northeastern Illinois, and northern Indiana, and in parts of Canada. They are also found in a Lake Erie tributary in New York and certain tributaries of the St. Lawrence River in Quebec, Canada. (Hubbs and Lagler, 1958)

What kind of habitat do they need?

The habitat of northern brook lamprey varies throughout the life cycle. Adults are generally found in areas of rapidly flowing water above a very coarse bed, spawning and then laying eggs in crevices beneath rocks and boulders. Ammocoetes (larvae) are generally found in the the calmer waters of brook, stream and river side channels where there is fine sediment or organic debris in which to burrow. (Hubbs and Lagler, 1958; "Ichthyomyzon fossor: Northern Brook Lamprey", 2012)

  • Aquatic Biomes
  • rivers and streams
  • Range depth
    0.7 (low) m
    2.30 (low) ft

How do they grow?

Northern brook lamprey have two developmental stages: ammocoete (larval) and adult. Larvae hatch approximately 2 weeks after egg fertilization and drift downstream before burrowing into the substrate. Once settled in burrows, larvae feed on suspended algae, bacteria and other detrius for 5-6 years until they metamorphose into non-feeding juveniles, typically in the fall. The transformation process lasts for 2-3 months. Juveniles spend 4-6 months drifting until spring, when spawning occurs and they become sexually mature adults. Adults die shortly after spawning. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007; "Ichthyomyzon fossor: Northern Brook Lamprey", 2012)

How do they reproduce?

During mating, 3-7 northern brook lamprey will build a nest together and spawn in groups of 10-30. Once eggs are fertilized and laid they are often covered with the substrate surrounding the nest. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

Northern brook lamprey spawn in the spring at approximately 6 years of age, just after reaching sexual maturity. Females lay thousands of eggs, possibly due to high mortality rates during the early stages of the species' life cycle. Eggs hatch 2-4 weeks after fertilization. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

Spawning is initiated when water temperatures are between 13 and 20.5°C. Males begin nest building by moving stones and gravel to create a small dip in the substrate within shallow, pool-riffle, high-gradient stretches of streams. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

During spawning, these lampreys coil together in groups of 3 to 7 individuals before going into the nest. Once in the nest a male attaches to, but does not wrap around, a female (as in some other lamprey species) to complete egg fertilization. Adults then leave the nest and die soon thereafter. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

  • How often does reproduction occur?
    Northern brook lamprey spawn once during their lifetimes.
  • Breeding season
  • Range number of offspring
    1,115 to 1,979
  • Average number of offspring
  • Range age at sexual or reproductive maturity (female)
    5 to 7 years
  • Range age at sexual or reproductive maturity (male)
    5 to 7 years

There is no parental investment by adults of this species as they die soon after egg fertilization. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

  • Parental Investment
  • no parental involvement

How long do they live?

Northern brook lamprey typically live for 5-8 years in the wild, dying within a few days of reaching sexual maturity and completing mating. There is no data available regarding captive lifespan. ("Ichthyomyzon fossor: Northern Brook Lamprey", 2012)

  • Average lifespan
    Status: wild
    7 years
  • Typical lifespan
    Status: wild
    5 to 8 years

How do they behave?

Northern brook lamprey are solitary outside of breeding season. This species is also mainly sessile, spending the first 4-6 years of its life in a burrow until they complete metamorphosis. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

Home Range

No information is currently available regarding the home range of this species.

How do they communicate with each other?

Although ammocoetes are blind, adult Northern brook lamprey have small eyes. This species also has a lateral line through which the fish may sense vibrations. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

What do they eat?

Northern brook lamprey only feed as ammocoetes. During this time, they feed mainly on organic detrius, diatoms, desmids, protozoans, algae and pollen. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007; Hubbs and Lagler, 1958; "Ichthyomyzon fossor: Northern Brook Lamprey", 2012)

  • Plant Foods
  • pollen
  • algae

What eats them and how do they avoid being eaten?

This species is prey for many larger fish throughout its life. While eggs and ammocoetes are particularly vulnerable, adults may be consumed as well. Known predators include rainbow trout, rock bass and brown trout. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

What roles do they have in the ecosystem?

Although morthern brook lamprey often share habitat with mayfly nymphs and small mussels, there is little evidence that there is any competition amongst these species. Unlike many lamprey species, this species is non-parasitic. There is currently no research available regarding parasites of northern brook lamprey. ("Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor", 2007)

Do they cause problems?

There are no known adverse effects of northern brook lamprey on humans.

How do they interact with us?

Although there is little known positive impact of northern brook lamprey on humans, fishermen do occasionally use this species as bait (Cumley, 1969)

Are they endangered?

The Minnesota DNR lists northern brook lamprey as a species of special concern. In order to keep game fish populations high and parasitic sea lamprey populations low, a lampricide treatment is put into streams and rivers where many lamprey, including non-parasitic northern brook lamprey, reside. This lampricide, among other poisons and pollutants, is adversely affecting population size. There is not currently a direct management/conservation plan in place for this species. ("Ichthyomyzon fossor: Northern Brook Lamprey", 2012)


Bronte Karvel-Fuller (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.


uses smells or other chemicals to communicate


an animal that mainly eats decomposed plants and/or animals


particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


union of egg and spermatozoan


a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.


mainly lives in water that is not salty.


An animal that eats mainly plants or parts of plants.


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season


remains in the same area


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


Commitee on the Status of Endangered Wildlife in Canada (COSEWIC). Assesment and Update Status Report on the northern brook lamprey Ichthyomyzon fossor. Canada: Her Majesty the Queen in Right of Canada. 2007. Accessed April 24, 2012 at

Minnesota Department of Natural Resources. 2012. "Ichthyomyzon fossor: Northern Brook Lamprey" (On-line). Minnesota Department of Natural Resources. Accessed April 02, 2012 at

2010. "The Northern Brook Lamprey (Great Lakes - Upper St. Lawrence)…a Species at Risk" (On-line). Fisheries and Oceans Canada. Accessed April 02, 2012 at

Cumley, R. 1969. Fisherman's Guide to Minnesota Fishes. Houston, Texas: Professional Publication Producers.

Dickson, T., J. Tomelleri. 2008. The great Minnesota fish book. Minneapolis, MN: University of Minnesota Press.

Felbaum, M. 2007. "Northern Brook Lamprey" (On-line pdf). Accessed April 02, 2012 at

Hubbs, C., K. Lagler. 1958. Fishes of the Great Lakes Region. Bloomfield Hills, Michigan: Cranbrook Institute of Science.

Loan-Wilsey, A. 2012. "Iowa Fish Atlas: Northern brook lamprey-Ichthyomyzon fossor" (On-line). Accessed April 02, 2012 at

Neave, F., N. Mandrak, M. Docker, D. Noakes. 2007. An attempt to differentiate sympatric Ichthyomyzon ammocoetes using meristic, morphological, pigmentation, and gonad analyses. Canadian Journal of Zoology, 85: "549-560".

Phillips, G., W. Schmid, J. Underhill. 1982. Fishes of the Minnesota Region. Minneapolis, Minnesota: University of Minnesota Press.

Potter, I., F. Beamish. 1975. Lethal Temperatures in Ammocoetes of Four Species of Lampreys. Zoologica, 56: "85-91".

Simon, T. 2006. Biodiversity of fishes in the Wabash River: Status, indicators, and threats. Proceedings of the Indiana Academy of Sciences, 115/2: 136-148. Accessed October 27, 2012 at

Yap, M., S. Bowen. 2003. Feeding by Northern Brook Lamprey (Ichthyomyzon fossor) on Sestonic Biofil Fragment: Habitat Selection Results in Ingestion of a Higher Quality Diet. Journal of Great Lakes Research, 29/1: "15-25".

University of Michigan Museum of ZoologyNational Science Foundation

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Karvel-Fuller, B. 2013. "Ichthyomyzon fossor" (On-line), Animal Diversity Web. Accessed April 21, 2014 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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