Lampetra richardsoni

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General Information
Common Name: 
Western brook lamprey

Conservation Status in California: Class 2, Vulnerable (Moyle et al. 2011).

Life History: 

Life History: Most of the information relating to this species comes from studies outside of California (Schultz 1930, McIntyre 1969, Kostow 2002), with the exception of a study by Hubbs (1925). Spawning adults build nests slightly smaller in diameter than their body lengths in gravel riffles. Western brook lamprey in Mark West Creek (April 1994) built nests 15-20 cm wide in gravel riffles at a depth of about 15 cm (M. Fawcett, pers. comm. 1998). Each nest was primarily excavated by the largest individual (assumed female) but held 2-4 individuals. In the Smith River, Oregon, most nests were 12 cm (length) by 11 cm (width) by 3 cm (depth) and were located in 13 cm deep, slow (0.2 m/sec) moving water (Gunckel et al. 2006). Median substrate size in nests was 24 mm and most (86%) nests were associated with cover (boulder, wood, vegetation). Sixty eight percent of the nests were found in either pool tail outs or low gradient ( Spawning behavior is similar to that of Pacific lamprey (Schultz 1930, Morrow 1980). In Cedar Creek, 3 to 12 lampreys were observed working together to move large rocks out of the nest prior to spawning (Stone et al. 2002). Upon completion of the nest, adhesive eggs are deposited and covered with sand and gravel (summarized in Kostow 2002). Adults die after spawning. The length of the spawning season varies from 6 months in Washington (Schultz 1930), where flow conditions are more constant, to fairly short (March-April) in Coyote Creek (Alameda County) (Hubbs 1925). Fecundity ranges from 1,100 to 5,500 eggs per female (Wydoski and Whitney 1979, Kostow 2002). Eggs hatch in about 30 days at 10°C, 17 days at 14°C, 12 days at 18°C and 9 days in 22°C (Meeuwig et al. 2005). Speckled dace (Rhinichthys osculus) and salmonids (Oncorhynchus spp.) feed on eggs in and around lamprey nests (Brumo 2006).
After hatching, freed embryos and larvae can spend another week to a month in the nest (summarized in Kostow 2002). Once they reach about 10 mm, they leave the nest and move downstream, usually at night, to burrow into deposits of fine sediments, their mouths towards the substrate surface so that they can filter feed. Ammocoete movement occurs year-round, mostly at night (Kostow 2002), but is primarily associated with increases in discharge and transformation (Stone et al. 2002). Ammocoetes move further downstream into deeper areas as they grow (Kostow 2002). Ammocoetes in aggregations as dense as 170 per square meter are most common in sand and silt areas of backwaters and pools (Schultz 1930). Although densities in two sites of the South Fork Walla Walla River, Washington and Oregon, were 4.8 and 36.7 individuals per square meter (Close et al. 1999). Western brook lamprey live as ammocoetes for 3-4 years in California and Oregon, and 4-6 years in British Columbia (Hubbs 1925, Schultz 1930, Pletcher 1963, Wydoski and Whitney 1979). California populations grow the fastest and largest (13-18 cm) by feeding on algae (especially diatoms) and organic matter (Wydoski and Whitney 1979). Ammocoetes begin transforming in the fall and mature by spring. Individuals develop eyes and an oral disc and undergo physiological changes in the gills and nasopineal gland (Kostow 2002). They become dormant in burrows during the transformation stage and do not feed as adults.
Where both western brook and Pacific lamprey occur, there can be some overlap in spawning habitat; in some cases western brook lamprey will spawn within Pacific lamprey nests (Stone et al. 2002, Luzier and Silver 2005, Brumo 2006, Gunckel et al. 2006). However, western brook lamprey more commonly will spawn further upstream in smaller tributaries than Pacific lamprey. Studies are currently underway to examine whether the bile acid petromyzonol sulfate is used as a chemical cue between conspecifics (Yun et al. 2003), perhaps influencing within-river distribution.

Habitat Requirements: 

Habitat Requirements: Western brook lamprey have similar habitat requirements to that of salmonid species with which they co-occur. They need clear, cold water in little disturbed watersheds as well as clean gravel near cover (boulders, riparian vegetation, logs etc.) for spawning. Additionally, they need habitats with slow moving water and fine sediments for rearing. Habitat use surveys of spawning western brook lamprey in Cedar Creek, Washington (Luzier and Silver 2005) found that adults avoided areas with deep, fast water and large substrate, suggesting specific habitat needs for spawning. Lamprey presence was positively correlated with temperature, percent fine substrate and dissolved oxygen and negatively correlated with stream gradient, velocity, percent bedrock and percent large gravel (Stone et al. 2002). In the Tualatin River basin, Oregon, western brook lamprey were most commonly found in shady glides or riffles with small substrate (soil or rock), in stream reaches without obvious signs of habitat degradation (Leader 2001). Optimum temperatures for embryo and larval development fall between 10 to 18°C (Meeuwig et al. 2005).


Distribution: Western brook lamprey live in coastal streams from southeastern Alaska south to California and inland in the Columbia and Sacramento-San Joaquin River drainages (Vladykov 1973, Morrow 1980). California populations are primarily found in the Sacramento River watershed, including remote areas such as Kelsey Creek upstream of Clear Lake (Lake County) and St. Helena Creek (Lake County), a tributary to upper Putah Creek. They are also found upstream Pillsbury Reservoir in the Eel River (Mendocino County) (Brown and Moyle 1996) and in a tributaries to the Russian River, Mark West Creek (Sonoma County) (M. Fawcett, pers. comm. 1998) and Austin Creek (J. Katz pers. comm. 2009). Spawning adults have been collected from the Navarro River (Mendocino County) (J.B. Feliciano, pers. comm. 1999). Ammocoetes were collected from the Los Angeles River (Culver and Hubbs 1917, C.L. Hubbs, pers. comm. 1974), a population now extirpated (Swift et al. 1993). Hubbs (1925) also collected ammocoetes from Coyote Creek, Santa Clara County. They most likely occur in many other large coastal rivers systems (Moyle 2002).

Abundance Trends: 

Trends in Abundance: Western brook lamprey are probably more common than surveys indicate because they are difficult to distinguish from other species (Kostow 2002, Moyle 2002). However, they are likely sensitive to pollution and habitat alteration so that they are restricted to stream reaches that are less disturbed. In Oregon, western brook lamprey are assumed to occur in less than half of their historic habitat in the Columbia River and Willamette River subbasins (ODFW 2006). Consequently, they are considered to be “at risk” due to habitat loss, passage barriers and pollution. However, they are still common in other parts of Oregon such as the Smith River (tributary to the Umpqua River) were an estimated 4692 (2004) and 4265 (2005) nests were made by western brook lamprey (Gunckel et al. 2006). Abundance data for California is not available.


Description: Western brook lamprey are small, usually less than 18 cm TL, and nonpredatory (Moyle 2002). They have poorly developed tooth plates in the oral disc but tooth plates in spawning adults may be missing from the anterior field. The supraoral plate is wide with one cusp at each end. The infraoral plate has 6-10 toothlike cusps and 3 circumoral plates on each side of the mouth. The middle circumoral plate has 2 or 3 cusps. Cusps on the transverse lingual lamina are inconspicuous. The oral disc is narrower than the head with a length that is less than 6 percent of the total length. Both adults and ammocoetes have trunks made up of 52-67 myomeres (52-58 in California populations). Body coloration is dark on the sides and back, and light (yellow or white) on the underside. Ammocoetes have dark tails and heads above the gill opening (Richards et al. 1982).