The Lampreys (family Petromyzonidae, stone suckers) belong to a small but important group known as Agnatha, the most primitive of all living vertebrates. They superficially resemble eels but are unrelated. Three species are native to the Columbia River basin, the Pacific lamprey (Lampetra tridentata), the river lamprey (L. ayresi), and the western brook lamprey (L. richardsoni). The Pacific and river lamprey are both anadromous and parasitic species and the western brook lamprey is nonanadromous and nonparasitic. On January 23, 2003, a petition was filed by eleven conservation groups to list these three species as endangered or threatened under the Endangered Species Act.

For more information on Lamprey Conservation click here to open the USFWS Pacific Lamprey Assessment Fact Sheet.

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  • NOTES: Lamprey are active at night as well as the day. Adult lamprey counts at some fish ladders are video tapped during the evening hours and then reviewed later. The way in which counts are completed have changed over the years. For instance, at Rocky Reach Dam, from 1996 through 2007, there has been video monitoring 24 hours a day. From 1995 through 1992, there was direct monitoring for the adult counts at Rocky Reach Dam from 0400-2000. This means that caution should be used when comparing newer adult count data with older count data. To see an adult count data collection schedule for each dam click here.
  • Lamprey Condition Monitoring Photos

    • Click HERE to view a slide show of photographs that were taken during the pilot study of conducting condition monitoring on larval and juvenile lamprey at John Day Dam in 2011. Download the 2011 Lamprey Report to the Lamprey Technical Workgroup for more information on this pilot condition monitoring program.

Lamprey life history

There is very little known about the life history of lamprey species and the data that is available is patchy and incomplete. Larval lampreys are referred to as ammocoetes. They are pale brown, have a fleshy toothless oral hood instead of sucker-like disc, and undeveloped eyes. They spend up to six years burrowed in the sediment, feeding on diatoms and detritus by filtering the water column. Physical cues initiate transformation and the river and Pacific lamprey enter a juvenile stage termed macropthalmia. At this stage the lampreys are silver in color, develop teeth and a sucker-like disc, and form true eyes. Physiological transformations occur that initiate migratory behaviors and enable them to tolerate sea water. They spend up to two years as adults in the ocean, feeding on fishes and mammals. Conversely, the western brook lamprey undergoes transformation directly into a non-feeding adult. All three species of lamprey are highly prolific, they spawn in freshwater during the spring, and die after spawning.

Information about identification of lamprey

Species differentiation is difficult at the larval stage for these three species of lamprey and is based largely on pigmentation. Transformers are identified by dentition, with Pacific lamprey having three sharp cusps, the river lamprey having two sharp cusps, and the western brook having two dull cusps. Adults are much easier to differentiate. Pacific lamprey attend maximum lengths of 70 cm, are bluish gray in the sea or during upstream migration and are dark brown on the spawning grounds. River lamprey have similar color patterns as the Pacific lamprey, but only attain a maximum size of 30 cm. Western brook lamprey attain a maximum length of 15 cm and are dark brown.

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