Lampetra hubbsi

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General Information
Common Name: 
Kern brook lamprey
FID: 
PLH01
Status: 

Conservation Status in California: Class 2, Vulnerable (Moyle et al. 2011).
Status is uncertain, but the Kern brook lamprey should be treated as a threatened species until better information is available to demonstrate otherwise. All populations are in regulated rivers and most are below dams.

Life History: 

Life History: No documentation of the life history of Kern brook lamprey exists. However, if the life history is comparable to that of other non-parasitic brook lampreys, they should live for approximately 4-5 years as ammocoetes before metamorphosing into adults. Metamorphosis occurs during fall. The adults presumably over-winter and spawn the following spring after undergoing metamorphosis.

Habitat Requirements: 

Habitat Requirements: Principal habitats of Kern brook lamprey are silty backwaters of large rivers in the foothill regions (mean elevation= 135 m; range= 30-327 m). In summer, ammocoetes are usually found in shallow pools along edges of run areas with slight flow (L.R. Brown, pers. comm.) at depths of 30-110 cm where water temperatures rarely exceed 25EC. Common substrates occupied are sand, gravel, and rubble (average compositions being 40%, 22%, 23%, respectively). Ammocoetes seem to favor sand/mud substrate where they remain buried with the head protruding above the substrate and feed by filtering diatoms and other microorganisms from the water. This type of habitat is apparently present in the siphons of the Friant-Kern Canal. Adults require coarser gravel-rubble substrate for spawning. Temperature requirements for Kern brook lamprey are not known but the fact they are present almost entirely in reaches where summer temperatures rarely exceed 24 degrees C is suggestive of a cool-water requirement.

Distribution: 

Distribution: The Kern brook lamprey was first discovered in the Friant-Kern Canal, but it has since been found in the lower reaches of the Merced River, Kaweah River, Kings River, and San Joaquin River, as well as in the Kings River above Pine Flat Reservoir and the San Joaquin River above Millerton Reservoir (Brown and Moyle 1987, 1992, 1993; Fig. 1). In 1988, ammocoetes and adult lampreys were found in several siphons of the Friant-Kern Canal, when they were poisoned during an effort to rid the canals of white bass (Morone chrysops). The "low-count" lampreys (i.e., low numbers of trunk myomeres) reported from the upper San Joaquin River between Millerton Reservoir and Kerckhoff Dam (Sierra National Forest) by Wang (1986) are also most likely L. hubbsi, as are similar ammocoetes from the Kings River above Pine Flat Reservoir (Sierra and Sequoia National Forests).

Abundance Trends: 

Trends in Abundance: Since this species was first discovered in 1976, attempts to fully document its range have been only partially successful. However, data collected to date suggest that this species is a San Joaquin endemic (Brown and Moyle 1992, 1993). Isolated populations of Kern Brook lamprey seem thinly distributed throughout the San Joaquin drainage, and their abundances are probably much reduced. Ammocoetes thrive in the dark siphons of the Friant-Kern Canal, but it is unlikely that there is suitable spawning habitat in the canal, so those individuals probably do not contribute to the persistence of the species.

Description: 

Description: The Kern brook lamprey is a non-predatory lamprey endemic to the San Joaquin and Kings river drainages (Brown and Moyle 1992). Its morphology is like that of other lampreys: eel-like body, no paired fins, and a sucking disc instead of jaws. Larvae, known as ammocoetes, are similar to adults in shape but lack eyes and a well-developed oral disc. The Kern brook lamprey is much smaller than predatory anadromous lampreys; adults range from 81 to 139 mm TL and ammocoetes from 117 to 142 mm TL. Ammocoetes are typically larger than adults because non-predatory lampreys shrink following metamorphosis (Vladykov and Kott 1976). The number of trunk myomeres (i.e. the "blocks" of muscle mass along the body) ranges from 51 to 57 in ammocoetes (Tables 1, 2). In adults, the supra-oral lamina (tooth) typically has 2 cusps, with 4 inner lateral teeth on each side of the disc. The typical cusp formula is 1-1-1-1 (Vladykov and Kott 1976). The sides and dorsum are a grey-brown and the ventral area is white. Dorsal fins are unpigmented, but there is some black pigmentation restricted to the area around the notochord in the caudal fin (Vladykov and Kott 1976).