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New Jersey Endangered and Threatened Species Field Guide

Image of American brook lamprey.Zoom+ American brook lamprey. Photo courtesy of Shawn Crouse.

American brook lamprey

Lethenteron appendix

Species Group: Fish

Conservation Status

State: Special Concern



Lamprey are an ancient and primitive group of jawless vertebrates, dating back to before the time of the dinosaurs. They are eel-like fish which lack jaws, scales, paired fins, or bones. Adults have a cartilaginous skeleton and 7 pairs of porelike gill openings.

This lamprey species grows to 13 ¾ inches in length. It has a disc-like sucker mouth which is narrower than its head. The disc-shaped mouth has blunt teeth – the arrangement of the teeth is often the best way to distinguish lamprey species.

There are two dorsal fins which are connected at the base. Color is lead gray to slate blue above, white below, with yellow dorsal fins. There is a dark blotch on the caudal fin. Breeding adults are olive green or pink-purple to shiny black above with a black stripe at the base of the dorsal fins.

Image of Range of the American brook lamprey in New Jersey.Zoom+ Range of the American brook lamprey in New Jersey.


This species has a very patchy, disjunct range within the eastern half of the United States. It can be found as far south as northern Alabama, west to Arkansas, north to the upper peninsula of Michigan as well as southern Ontario and Quebec, and along the eastern seaboard. Its distribution within New Jersey is also very patchy and disjunct.

Habitat for adults is freshwater creeks and small to medium rivers with gravel-sand riffles and cool, clear water. Larvae will burrow into sand and silt, often in pools or slow water.


Though most species of lamprey are parasites, this species is a non-parasitic lamprey. Larvae are filter-feeders, feeding on plankton. Adults do not feed.


Spawning occurs in spring (March-April). Adults excavate pits in stream riffles to use as spawning sites. The small, white, sticky eggs hatch in a few days to a few weeks, depending on temperature. The emerging larvae are blind and known as ammocoetes. The larval stage may last for several years. They then metamorphose into sexually mature adults in late summer or fall and stop feeding. Adults die after spawning.


This species is sensitive to environmental degradation. Populations within New Jersey are patchy and disjunct. Its population has declined in New Jersey and it has disappeared from portions of its range in the state.

In 2016, the New Jersey Endangered and Nongame Advisory Committee recommended a Special Concern status for this species, but no formal rule proposal has been filed to date.

Text written by Michael J. Davenport in 2016.


  • Arndt, Rudolf G. 2004. “Annotated Checklist and Distribution of New Jersey Freshwater Fishes, With Comments on Abundance.” The Bulletin: New Jersey Academy of Scince. Vol. 49, No. 1.
  • Page, Lawrence M. and B.M. Burr. 2011. Peterson Field Guide to Freshwater Fishes of North America North of Mexico.
Scientific Classification

Kingdom: Animalia
    Phylum: Chordata
       Class: Petromyzontida
          Order: Petromyzontiformes
             Family: Petromyzontidae
                Genus: Lethenteron
                   Species: L. appendix

Find Related Info: Fish, Special concern

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