Lavinia symmetricus symmetricus

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General Information
Common Name: 
Central California roach
FID: 
CLS01
Status: 

Conservation Status in California: Class 3, Near-threatened (Moyle et al. 2011).
Although there is no known extinction risk for the form as a whole, there exists high uncertainty as to abundance, status and taxonomy of many populations. Specific populations are increasingly isolated by human habitat alteration (i.e., dams, reservoirs, urbanization, pollution and introduced species) and may be declining. Additionally, because roach systematics are poorly understood, there is risk that small distinctive populations may be lost before they can be formally described and provided the protection they deserve as distinct taxa.

Life History: 

Life History: Roach are opportunistic omnivores whose diet varies greatly across, watershed, habitat type and season. In small warm streams they primarily graze filamentous algae, which is seasonally abundant, although they also ingest crustaceans and aquatic insects, which can account for nearly a third of stomach contents by volume (Fry 1936, Fite 1973, Greenfield and Decket 1973). In larger streams, such as the North Fork Stanislaus River, roach have been observed to feed on drift (Greenfield and Decket 1973, Moyle 2002) and aquatic insects may dominate the diet year-round (Roscoe 1993). Juvenile roach consume large quantities of crustaceans and small chironomid midge larvae while adult roach are more opportunistic feeders, feeding both off the substrate and from drifting insects in the water column. While roach are primarily benthic feeders, in the Tuolumne River, Moyle (2002) observed roach feeding in swift current on drift organisms, including terrestrial insects. Adult roach show little preference for food type and small midge, mayfly, caddisfly and stonefly larvae along with elmid beetles, aquatic bugs and amphipods, are taken roughly in proportion to their availability in the benthos and drift (Fite 1974, Roscoe 1993, Feliciano 2004). Adult roach have also been observed to consume larger prey, and one individual in the Navarro River contained three larval lampreys (Moyle 2002). As a result of their benthic feeding habits, the stomach contents of adult roach are often found to contain considerable amounts of detritus and fine debris. It is thought that roach extract some nutritional value from this material because its retention is facilitated by the gill rakers and mucus secretions from epithelial cells (Sanderson et al. 1991).
Growth is highly seasonal, with most rapid growth typically occurring in early summer (Fry 1936, Barnes 1957). In perennial streams roach frequently exceed 40 mm SL in their first summer, reach 50-75 mm by their second year and reach 80-95 mm SL by their third summer (Roscoe 1993, Fry 1936). Few individuals get bigger than 120 mm SL or live beyond 3 years, although a 6 year-old specimen was recorded in San Anselmo Creek, Marin County (Fry 1936).
Roach typically mature at 45-60 mm SL in their second or sometimes third year (Fry 1936). Fecundity is dependent on size and ranges from 250 – 2,000 eggs per female (Fry 1936, Roscoe 1993). Spawning activity is largely dependent on temperature, and typically occurs in March through early July when water temperatures exceed 16°C. Spawning occurs in riffles over small rock substrates, 3-5 cm in diameter. Roach spawn in large groups over a coarse substrate, each female repeatedly deposits eggs, a few at a time, into the interstices between rocks where they are immediately fertilized by one or more attendant males. Spawning aggregations can be quite conspicuous and spawning fish can splash so vigorously that, at times, the splashing can be heard at some distance (Moyle 2002). This activity clears silt and sand from interstices of the gravel which improves habitat for sticky fertilized eggs which adhere to the rocks. Eggs hatch after 2-3 days, and larvae remain in the gravel until large enough to actively swim. Larval development is described by Fry (1936). The population from Bear Creek, Colusa County, apparently spawned in emergent vegetation and newly hatched larvae remained among the plants for some time (Barnes 1957). Once the yolk is absorbed, larval roach feed primarily on diatoms and small crustaceans (Fry 1936).
Larval drift may be a significant form of dispersal for roach. Roach embryos and larvae made up a significant portion of the nighttime planktonic drift (approximately 10%) in the Van Duzen River (introduced population) in late May through July of 1997 (White and Harvey 2003). White and Harvey (2003) suggest that because roach larvae which can resist downstream displacement and because roach spawn in late spring as flows recede, they probably face a limited risk of drifting downstream into unsuitable habitats types. In the Central Valley, these attributes would assist young roach from ending up in valley-floor habitats.

Dispersal Capability: Freshwater obligate; only capable of natural colonization via hydrologic stream connection. The ability of roach to persist in small, high gradient, often intermittent tributaries has led, through the erosional capture of interior headwater streams, to their colonization of adjacent drainages (Snyder 1908, 1913, Murphy 1948c, Moyle 2002). Accordingly, roach (and sometimes Sacramento sucker) are often the only freshwater obligate fishes to colonize some coastal drainages, including the Gualala and Navarro watersheds. Because they are relatively intolerant of saline waters, dispersal to these coastal streams could not have occurred through ocean waters, although connections at low elevations may have been possible in some cases when sea level was lower (Moyle 2002). Similarly, populations in San Francisco Estuary are isolated from each other, to some extent, by the inability of roach to disperse through saline Bay waters. Exchange between populations may nevertheless occur during flood years when freshwater outflow is great enough to create freshwater lenses in the surface waters of the Bay, thus allowing fish intolerant of saline waters to exchange between Bay watersheds and permitting inland fish swept downstream from the Valley access to Bay tributaries (Ayers 1862, Snyder 1905, Murphy 1948c, Leidy 2007). During high water periods, fish may also have been able to disperse through flooded marshes on the fringes of the Bay. Today, it thought that such dispersal happen only very rarely, if at all, because the marshes and floodplains that once fringed the estuary have been destroyed or narrowed to such a degree as to make movement between watersheds very difficult for a fish as small as roach (Leidy pers. comm. 2007).
Its small size makes it attractive as bait and increases risk of illegal “bait bucket” transfer between watersheds by anglers.

Habitat Requirements: 

Habitat Requirements: Central California roach are generally found in small streams and are particularly well adapted to life in intermittent watercourses; dense populations are frequently observed in isolated pools (Fry 1936, Moyle et al. 1982, Leidy 2007). Roach are most abundant in mid-elevation streams in the Sierra Nevada foothills and in lower reaches of some San Francisco Bay streams but they may be found in the main channels of some rivers such as the Stanislaus (Roehrig 1988) and Tuolumne (Moyle 2002). They tolerate a relatively large range of temperatures and dissolved oxygen levels, being found in habits as varied as cold, clear well-aerated “trout” streams (Taylor et al. 1982, Roscoe 1993) and intermittent streams where they can survive extremely high temperatures (30 to 35° C) and low dissolved oxygen levels (1-2 ppm) (Taylor at al. 1982, Knight 1985, Cech et al. 1990).
Roach commonly occur throughout the entire length of streams tributary to the San Francisco estuary but they are intolerant of saline waters (Moyle 2002). They have been recorded in salinities up to 3 ppt, but perish before salinities reach 9-10 ppt (Moyle unpublished data). In headwater reaches of San Francisco Estuary tributaries roach typically co-occur with rainbow trout, juvenile Sacramento sucker and prickly or riffle sculpin (Leidy 2007). In small warm intermittent estuary streams they are most often found with juvenile Sacramento suckers and occasionally with green sunfish (Lepomis cyanellus) (Leidy 2007). In lower mainstem stream channels roach occur as part of a predominately native fish assemblage which, depending on location, is characterized by assemblages consisting of combinations of Pacific lamprey, Sacramento pikeminnow, hardhead, Sacramento sucker, riffle sculpin, prickly sculpin and tule perch (Leidy 2007).
Although emblematic of streams that support native fishes, roach are most abundant when found by themselves or with just one or two other species (Moyle and Nichols 1973, Leidy 1984, 2007, Brown and Moyle 1993). When found alone, roach will occupy open water in large pools; when found as part of complex assemblages, roach tend to congregate in low velocity ( While roach rarely display aggressive behavior towards other fish, they are important predators of lower trophic levels and may play a key role in regulating aquatic food webs, especially in watersheds where they are introduced. For instance, using net-pen mesocosms experiments, Power et al. (1992) demonstrated that introduced roach suppressed benthic insects and affected persistence of algae in the South Fork of the Eel River.
Water temperatures in many Eel River tributaries have substantially warmed over the last 50 years. This change in thermal regime is attributed to a combination of human activities, primarily heavy logging, and to the large floods of the 1950’s and 1960’s which dramatically altered channel configurations (Moyle and Nichols 1973, Harvey et al. 2003). Harvey et al. (2003) suggest that these changes in temperature regime enhanced the invasion of the drainage by California roach and Sacramento pikeminnow. Evidence from the Gualala and Navarro Watersheds also suggests that human alteration of coastal watersheds creates thermal regimes favorable to roach.

Distribution: 

California Distribution: Central California roach are found in the tributaries to the Sacramento and San Joaquin rivers and in the tributaries to San Francisco Bay. Their historic distribution in the upper Sacramento River basin is poorly understood but their upstream range limit is thought to be Pit River Falls. Roach found above the falls are northern roach (L. mitrulus).
In Central California, the taxon consists of many populations that are isolated to varying degrees. This isolation was partially natural because roach have a hard time persisting in valley floor habitats or in large rivers with piscivorous fishes (Brown et al. 1992b). Many of these isolated populations are distinguishable, both morphologically (Brown et al. 1993) and genetically (Aguilar et al 2009), but the interrelationships are complex and poorly understood. Gaps in their distribution (e.g., Fresno River) suggest recent extirpations (Brown et al. 1992b). One population, found in small streams in the Red Hills near Sonora, Tuolumne County, has been given subspecies status and it is possible that a thorough analysis of Lavinia systematics will recognize other taxonomically distinct populations (e.g., Cosumnes River, Peoria Creek, Kaweah River, Los Gatos Creek).
In a few instances, Central California roach may have had their range expanded through introductions. For example, Hetch-Hetchy Reservoir on the upper Tuolumne River supports a large pelagic population. Soquel Creek and the Cuyama River in southern California support apparent introduced populations, although genetic investigations may reveal that the both populations are native (Moyle 2002). The origin of the roach introduced into the Eel River drainage is not known.

Abundance Trends: 

California Trends in Abundance: In absolute terms, Central California roach are still abundant but there is growing evidence that Central Valley populations may be disappearing one at a time (Moyle and Nichols 1973, Moyle and Daniels 1982, Brown et al. 1992b, Brown and Brasher 1995). While relatively little information is available for roach populations in the Sacramento River Valley, in the San Joaquin Valley, surveys indicate that roach have been completely extirpated from the entire Fresno River watershed (Moyle 2002) and that between 1970 and 1990 roach were eliminated from many additional locations, such as much of the Cosumnes River (Moyle and Nichols 1973, Brown and Moyle 1991 & 1993, Moyle et al. 2003). In contrast, two intensive studies of the streams tributary to the San Francisco Bay estuary (Leidy 1984, 2007) found roach to be abundant (in both surveys they were the most commonly collected native fish) and populations to be relatively stable.

Description: 

Description: Central California roach are small, stout-bodied minnows (cyprinids) with a narrow caudal peduncle and a deeply forked tail. Fish rarely achieve lengths greater than 100 mm total length. The head is large and conical. The eyes are large and the mouth is subterminal and slants at a downward angle. Some populations, especially those in the streams of the Sierra Nevada, develop a cartilaginous plate on the lower jaw, often referred to as a “chisel lip”. The dorsal fin is short (7-9 rays) and is positioned behind the insertion point of the pelvic fin. The anal fin has between 6-9 rays. Fish with more dorsal and anal fins rays are likely hybrids with hitch (Lavinia exilcauda) (Miller 1945b). The pharyngeal teeth (0,5-4,0) have curved tips which overhang grinding surfaces of moderate size. Roach are usually dark on the upper half of their bodies, ranging from a shadowy gray to a steel blue, while the lower half of the body is much lighter, usually a dull white/silver color. The scales are small, numbering 47-63 along the lateral line and 32-38 before the dorsal fin. Subspecies are distinguished by various distinctive subsets of characters, especially fin ray and scale counts.
Roach exhibit general (non-nuptial) sexual dimorphism (Snyder 1908a, Murphy 1943). In the tributaries to San Francisco Bay, Snyder (1905, 1908a) demonstrated that the sexes could be differentiated by the ratio of pectoral fin length to body length. Males exhibited a ratio of >.21 while females bore pectoral fins between .16 and .20 the length of their body. Both sexes exhibit bright orange and red breeding coloration on the operculum, chin and the base of the paired fins. Males may also develop numerous small breeding tubercles (pearl organs) on the head (Murphy 1943).