Catostomus platyrhynchus

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General Information
Common Name: 
Lahontan mountain sucker
FID: 
CCP01
Status: 

Conservation Status in California: Class 3, Near threatened (Moyle et al. 2011).
The mountain sucker, when broadly defined as a species, is not in danger of extinction throughout its range. Nor does it appear to be at risk of extinction in California at the present time, although most California populations seem to be declining and their range is fragmented. However, the likelihood that Lahontan drainage populations represent a distinct taxon within the mountain sucker lineage provides cause for concern.

Life History: 

Life History: Most studies on mountain suckers took place outside of California but given the morphological similarity of the forms found throughout its range (Smith 1966), basic life history characteristics are also likely to be similar everywhere. Mountain suckers in Montana grow to 60-65 mm TL in their first year, 90-100 mm in their second year, and rarely exceed 17 cm TL as adults (Hauser 1969); growth rates in the first three years gradually decrease to a slow and constant rate. In Utah, they grow to 64 mm TL in their first year and reach 193 mm TL by the age of 6 years (Wydoski and Wydoski 2002). Growth is likely mediated by the temperature and productivity of the stream (Wydoski and Wydoski 2002). California mountain suckers likely have a similar growth pattern, based on length data (Moyle 2002). In populations that have been studied, males mature at 6-14 cm TL, during their second or third year (Smith 1966, Marrin 1980). Females are larger, tend to mature later (2nd to 4th year at 9-17 cm TL), and live longer (7-9 years) than males (Smith 1966, Marrin 1980, Wydoski and Wydoski 2002). Fecundity can vary between 990 (at 13 cm TL) to 3,710 (at 18 cm TL) eggs per female (Marrin 1980) and is correlated to female total length but not age (Wydoski and Wydoski 2002). Mean egg diameter is also correlated to female total length. Mean egg diameter ranged from 1.61-1.93 mm (mean = 1.77 mm) for 20 females captured from Lost Creek, Reservoir, Utah (Wydoski and Wydoski 2002).
Mountain suckers, unlike most stream-dwelling fishes in western North America, spawn in summer (June to early August) rather than spring (Hauser 1969, Olson and Erman 1987, Decker 1989). Spawning in Utah streams peaked in early June but took place from late May until the end of June (Wydoski and Wydoski 2002). In California, adults have been observed moving into small streams during later July to feed on algae and to spawn (Decker and Erman 1992). Spawning probably occurs at night in riffles located immediately below pools, at temperatures ranging from 9-19 °C (Hauser 1969, Olson and Erman 1987, Decker 1989, Wydoski and Wydoski 2002). However, spawning adults were noted in Sagehen Creek, California, at temperatures ranging from 9-12 °C (Decker 1989). In Utah, adults preferred to spawn in the current (6-20 cm/s) of riffles that were 11-30 cm deep (Wydoski and Wydoski 2002). Mountain suckers can hybridize with Tahoe suckers in streams (Decker 1989; T. Taylor, ENTRIX, pers. comm. 2009). Fertilized eggs adhere to stream substrates. Larvae and juveniles move into the stream margins, favoring areas with beds of aquatic algae associated with pools (Hauser 1969), or the shoreline of reservoirs (Wydoski and Wydoski 2002).
Mountain suckers feed primarily on algae and diatoms but will feed on aquatic invertebrates as well (Smith 1966, Marrin 1980). Juveniles ( Although most mountain suckers shoal exclusively with one another in other parts of their range (Hauser 1969), California populations have been observed shoaling with Tahoe suckers (Decker 1989) with which their abundance is positively correlated (Olson and Erman 1987). They are also often associated with alien brown and rainbow trout which may prey on them (Moyle 2002, Olsen and Belk 2005, Giddings et al. 2006).

Dispersal Capability: Only capable of natural colonization of new habitats via hydrologic stream connection. Although, they are now found in the North Fork Feather River (Sacramento River) drainage, mainly in Red Clover Creek, into which they were likely carried by a water diversion from the Little Truckee River (Moyle 2002). Although there is at least one specimen known from the Sacramento River, they do not appear to have spread much beyond Red Clover Creek.

Habitat Requirements: 

Habitat Requirements: Mountain suckers are characteristically found shallow ( Despite being usually inhabiting cool streams with high water quality, mountain suckers seem to be fairly tolerant of low water quality. Noble (1952) found that mountain suckers have higher tolerances to organic pollution and warm temperatures than most trout but lower tolerances than bullhead, largemouth bass and some native species such as lamprey. Unexpectedly, putative mountain suckers were the most abundant fish in some small urbanized streams in Utah that had low dissolved oxygen levels, high concentrations of dissolved nutrients and little cover (Giddings et al. 2006).
Habitat use may shift in the presence of piscivores such as brown trout (Salmo trutta). Juvenile mountain suckers, in central Utah, occurred in main channel pools when brown trout were absent but occurred exclusively in backwaters and off-channel habitats when brown trout were present (Olsen and Belk 2005). Adults, in contrast, did not exhibit a shift in habitat use, probably because they escaped predation once they reached a larger size. However, in streams in Wyoming and South Dakota high density of large brown trout was found to have a negative impact on occurrence of mountain suckers, regardless of age (Dauwalter and Rahel 2008).

Distribution: 

Distribution: Mountain suckers are widely distributed in western North America (Lee et al. 1980). In Canada, they are found in several rivers in Saskatchewan, Alberta, and British Columbia. In the United States, they are found in Montana, South Dakota, Wyoming, Colorado, Utah, Idaho, Washington, Oregon, California and Nevada. California populations occur in the Walker, Carson, Truckee and Susan River drainages of the Lahontan drainage of the eastern Sierra Nevada, but not in the Eagle Lake basin. A translocated population is now found in the North Fork Feather River (Sacramento River) drainage, mainly in Red Clover Creek, into which they were likely carried by a water diversion from the Little Truckee River (Moyle 2002).

Abundance Trends: 

Trends in Abundance: Mountain suckers are common in much of their range, but rare in Canada and Washington (Wydoski and Wydoski 2002). Mountain suckers appear to be in decline in their native range in California (Erman 1986, Olson and Erman 1987, Decker 1989, Moyle 2002). The evidence of decline is mostly anecdotal, where the suckers are rare or absent from streams from which they have been abundant in the past. For example, they disappeared from Sagehen Creek following the construction of Stampede Reservoir, into which the creek now flows (S. Boucher and P. Moyle, unpublished data). Mountain suckers, however, remain abundant in some streams, such as East Fork Cason River and its tributary, Hot Creek (Erman 1986). In 1988, the number of mountain suckers in the undammed East Fork Carson River was estimated to range from 1,000 to 44,000 per kilometer (J. Deinstadt, CDFG, unpubl. data, 1996). Declines can result from dams and reservoirs isolating populations (Moyle 2002). Mountain suckers rarely persist in reservoirs in California and small streams upstream of reservoirs can usually only support small populations, making them vulnerable to extirpation (e.g., Sagehen Creek). Once thought to occur in large numbers in the upper Truckee River (Moyle 2002), mountain suckers now are infrequently found there (T. Taylor, ENTRIX, pers. comm. 2009).

Description: 

Description: Mountain suckers are small (adults 12-20 cm TL), with subterminal mouths and full lips that are covered by many large papillae (Moyle 2002). Their lips are protrusible, and have deep grooves where the upper and lower lips meet and a cleft on the middle of the lower lip. The lower lip has two semicircular smooth areas along the inner margin next to a conspicuous cartilaginous plate that is used for scraping. The front of the upper lip is smooth. They have 75-92 scales along the lateral line and 23-37 gill rakers on the first gill arch. Fin rays typically number 10 (range 8-13) and 9 for the dorsal and pelvic fins, respectively. An axillary process is easily visible at the base of the pelvic fins. Internally, their intestine is long (up to 6 times TL), and the lining of the abdominal cavity (peritoneum) is black. Their coloration is brown to olive green on the dorsal and lateral surfaces, white to yellow on their bellies, and dark brown in blotches in a lateral row or line. Mature males have two lateral bands, one red-orange on top of one that is black-green. Spawning males have tubercles covering their bodies and fins, with the exception of the dorsal fin. Tubercles on the enlarged anal fin become especially prominent. Spawning females also have tubercles but only on the top and sides of their heads and bodies. Larvae have relatively few dorsal-fin rays and a complete midventral line of pigment from the heart to the vent (Snyder et al. 2004).