Species Profile

Chestnut Lamprey

Scientific Name: Ichthyomyzon castaneus
Taxonomy Group: Fishes
Range: Saskatchewan, Manitoba
Last COSEWIC Assessment: November 2010
Last COSEWIC Designation: Non-active
SARA Status: Schedule 3, Special Concern - (SARA Schedule 1 provisions do not apply)

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Image of Chestnut Lamprey

Chestnut Lamprey Photo 1



The Chestnut Lamprey is a small parasitic lamprey whose head ends in a buccal funnel. This lamprey has slender and sharp teeth, and a smooth leathery skin with no scales. Chestnut Lampreys are dark grey to olive, or yellow brown above with lighter underparts; at spawning time, the adults become blue-black. Chestnut Lampreys measure approximately 325 mm.


Distribution and Population

In Canada, the Chestnut Lamprey is found in some rivers of Saskatchewan and Manitoba. There are no estimates of the size of the Canadian population of this species.



Chestnut Lampreys inhabit moderate-sized rivers and large creeks. Spawning occurs from mid-June to late July, in areas of coarse gravel.



Chestnut Lampreys mate once between 7 and 9 years of age; they mate, spawn and then die shortly after the egg-laying has been completed. The young fish hide in burrows and feed on algae, plankton and protozoans. The adults attack a wide variety of stream fishes: they attach themselves to the body of the fish and consume its body fluids and muscles. These lampreys are only active at night; during the day, they hide from the light under rocks or under the cover of river banks.


The areas suitable for spawning of the lamprey are disappearing due to siltation and pollution. The deterioration of river environments also threatens their food supply. Toxic chemical pollution can cause mortality at all ages; eutrophication can cause mortality in the young.




PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

2 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Status Report on the Chestnut Lamprey Ichthyomyzon castaneus in Canada (2011)

    The Chestnut Lamprey is a parasitic species that attains a maximum size of 363 mm in total length as an adult and 165 mm as a larva. It has a single indented dorsal fin. Larger larvae (greater than approximately 95 mm) can be distinguished from all other Canadian lampreys by the presence of darkly pigmented lateral line organs. Adults can be distinguished from the two other Canadian lamprey species that have a single dorsal fin, Silver Lamprey and Northern Brook Lamprey, by possessing usually a total of six bicuspid inner lateral teeth, compared to usually none. There are two designatable units: a Saskatchewan-Nelson River DU and a Great Lakes-Upper St. Lawrence DU. This parasitic lamprey species is found in Canada (Saskatchewan, Manitoba, Ontario, and Québec) and the United States (19 contiguous states from North Dakota to Texas), but its closest relative, the Southern Brook Lamprey, a nonparasitic species, is only found in the United States.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2010 - 2011 (2011)

    Under Canada’s Species at Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. COSEWIC held two Wildlife Species Assessment Meetings during the past year assessing the status or reviewing the classification of a total of 92 wildlife species.