Lavinia mitrulus

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General Information
Common Name: 
Northern (Pit) roach
FID: 
CLS08
Native: 
1
Status: 

Conservation Status in California: Class 2, Vulnerable (Moyle et al. 2011).
This species appears to have just a few isolated populations in California which could decline rapidly and disappear in many areas as the result of alterations to streams, the introduction of alien fishes and water withdrawal for agriculture, in combination with changes in climate.

Life History: 

Life History: Northern roach presumably share much of their life history with the Central California roach but their life history has not been studied so this cannot be verified.

Dispersal Capability: Freshwater obligate; only capable of natural colonization via hydrologic stream connection. Over geologic time, this headwater species was likely transferred between basins by headwater stream capture. Its small size makes it attractive as bait and increases risk of illegal “bait bucket” transfer between basins by anglers.

Habitat Requirements: 

Habitat Requirements: Northern roach tend to be associated with habitats unlike those where roach are found in the rest of California, especially spring pools and swampy stream reaches (S. Reid, pers. comm. 2009). Thus, in Ash Creek and Rush Creek, Lassen and Modoc Counties, roach are found in small numbers inhabiting the weedy margins of streams and, in one case, an isolated spring pond (Moyle and Daniels 1982, S. Reid, pers. comm. 2009). They do not often occupy intermittent streams in the Pit system, as is usual with roach in the rest of their range. Instead speckled dace (Rhinichthys osculus) dominate these habitats.
Moyle and Daniels (1982) found that 94% of the fish species that co-occurred with Northern roach were also native. The most common associates were speckled dace (Rhinichthys osculus), Sacramento sucker (Catostomus occidentalis) and Pit sculpin (Cottus pitensis). The fact that roach occur as part of a predominately native fish assemblage has been observed elsewhere (Moyle and Nichols 1973, Leidy 1984, Brown and Moyle 1993, Leidy 2007). Moyle (2002) attributes the uncommon co-occurrence of roach with alien species to the tendency for roach to be easily displaced by invasive fish species, especially centrarchids.

Distribution: 

Distribution: In California, Northern roach are restricted to several tributaries of the Upper Pit River. It is likely that they once inhabited the meandering valley floor reaches of the Pit River in Big Valley, Modoc County, but this area is now completely dominated by alien species (Moyle and Daniels 1982). Roach have not been recorded from Goose Lake itself. The only record of roach from the high-gradient Californian streams that flow into the Lake from the Warner Mountains to the east is in the Lower portion of Willow Creek (Hendricks 1995). However, northern roach are commonly found in the northern tributaries of Goose Lake in Lake County, Oregon.
In a recent comprehensive sampling of the Oregon portion of the Goose Lake watershed, the Oregon Department of Fish and Wildlife (ODFW) found northern roach to be widespread and relatively abundant (>80 fish) in Dry, Drews, Hay, Dent, Muddy, and Augur Creeks (Heck et al. 2008). Roach populations in the terminal lake basins adjacent to Goose Lake in the high desert of Eastern Oregon may also belong to this species but distributional records are spotty and taxonomic relationships among these populations remain uncertain.
Pit River Falls, located five miles downstream of the town of Fall River Mills, Shasta County, divides the Pit River Basin into upper and lower drainages. The falls are, at least partially, a barrier to fish movement. Historically, they represented the northern range limit for some Sacramento River fish, such as the tule perch (Moyle 2002). Only roach found above Pit River Falls are considered northern roach, L. mitrulus. Roach found below the falls would have historically had unimpeded access to Sacramento River system and are assumed to be L. s. symmetricus. However, genetic studies have not been conducted and relationships remain uncertain.
Historical collecting trips to the Upper Pit River system captured only a few specimens (Rutter 1908, Hubbs et al. 1934, from field notes and collections at the University of Michigan as reported in Reid et al. 2003) or none at all (Snyder 1908a). In the most comprehensive sampling of the Pit system to date, Moyle and Daniels (1982) found roach, at only 8% of 261 collection sites. Above Pit River Falls, roach were found in only three drainages: (1) Ash–Rush–Willow Creek drainage, Lassen and Modoc counties, (2) Bear Creek, tributary to the Fall River, Shasta County and (3) Beaver Creek, Lassen County.

Abundance Trends: 

Trends in Abundance: Historically, roach were probably much more widely distributed in the upper Pit River drainage (e.g., Big Valley) but modern surveys have found that they have disappeared from reaches where they previously occurred (reviewed in Reid et al. 2003). Reid et al. (2003), in the only known survey of the Upper Pit Drainage since 1978, surveyed 12 sites in the North Fork, South Fork and upper mainstem Pit River (between Alturas and Rose Canyon) without collecting roach. The following is a history of roach occurrence in the upper Pit River basin:
North Fork Pit River. Rutter (1908), collecting in 1898, captured “a few small specimens” of roach. Snyder (1908), collecting in 1904 near the same location, did not capture any roach, while Hubbs and others collecting in the North Fork near Alturas in 1934 captured only 19 (from field notes and collections at the University of Michigan as reported in Reid et al. 2003). Subsequent collectors have found green sunfish but not roach (Moyle and Daniels 1982, Reid et al. 2003).
South Fork Pit River- Three historic sampling trips found roach in the South Fork. Modern collecting trips have not collected any (from information in Reid et al. 2003)
Mainstem Pit River, Alturas to Pit River Falls. The only known record of capture is a single specimen taken by R.R. Miller in 1961 (from field notes and collections University of Michigan as reported in Reid et al. 2003). This is the reach flowing through Big Valley which has been highly altered and contains mainly alien species (Moyle and Daniels 1982). However, roach remain common in the Ash Creek drainage (S. Reid pers. com. 2009).

Description: 

Description: Northern roach are small (adult size typically 50-100 mm) bronzy cyprinids. They have a robust body, deep caudal peduncle, short snout and short rounded fins. They are dark on the upper half of the body, light below and very similar in appearance to the Central California roach. Northern roach differ from Central California roach in having short rounded fins and “cup-like” scales (see Snyder 1913 for more detail on scale morphology). Snyder (1908a) published morphometric data on 20 fish from Drews Creek (among them the type specimen of the species) and all individuals had 8 dorsal rays and 7 fin rays. Averaged counts of fin rays from a larger collection could not be found. Snyder found that male roach had longer larger fins than did females, especially pectoral fins; and that the sexes could be differentiated by the ratio of pectoral fin length to body length. These differences in the relative fin length between the sexes led Snyder to publish one of the first accounts of general sexual dimorphism in cyprinid fishes.
See the Central California roach account, this volume, for a more in-depth description of general roach morphology.