Lavinia exilicauda exilicauda

Vertical Tabs

General Information
Common Name: 
Sacramento hitch
FID: 
CLE01
Status: 

Conservation Status in California: Class 3, Near threatened (Moyle et al. 2011). Sacramento hitch appear to exist only as scattered small populations over a fairly broad area, and seem to be in a long-term decline. Its status needs systematic investigation.

Life History: 

Life History: Sacramento hitch are omnivorous feeders on zooplankton and insects, usually in open waters or at the surface of streams (Moyle 2002). In streams, they feed filamentous algae, aquatic insects, and terrestrial insects. Small (5-7 cm SL) hitch will feed, like trout, on drift at the heads of pools during the summer. Hitch feed mostly during the day (Moyle 2002). In rivers, they tend to stay in fairly limited areas and have considerable capacity to find local refuges from high flows, in side pools (Jeffres et al. 2006). Myrick and Cech (2000), however, found they had difficulty sustaining swimming at velocities greater than 0.3 m/sec.
Growth is not well studied but appears to be related to summer temperatures of the environments in which they live. In San Luis Reservoir, hitch reach 11-15 cm by the end of their first year, and 15–30 cm by the end of the second year; when they mature. Subsequent increases are 20–50 mm/year, with a maximum size of around 35-40 cm. Hitch in Beardsley Reservoir, in contrast, are only 40–50 mm FL by the end of the first year and 9–11 cm FL by the end of their second, with subsequent increments of 20–40 mm/year. In Putah Creek they average about 65 mm FL at the end of their first year and reach 200–250 mm in 3–4 years. Females grow faster and larger than males. Scale analysis indicates that hitch live 4–6 years, but it is likely that analysis of the bony structures of large fish would yield greater ages (Moyle 2002).
Females usually mature in their second or third year; males mature in their first, second, or third year. Hitch are rather prolific: females from Beardsley Reservoir contained 3,000–26,000 eggs, with a mean of 9,000, but much higher fecundities (50-60,000 eggs) are likely in warmer habitats which contain large fish.
Spawning takes place mainly in riffles of streams tributary to lakes, rivers, and sloughs, after flows increase in response to spring rains, although spawning requirements are in need of further documentation. When they are present in ponds and reservoirs with Sacramento blackfish, the two species often hybridize, presumably because they are forced to share spawning areas.
Spawning is in groups, with much vigorous splashing. A spawning female is closely followed by 1–5 males, who fertilize eggs immediately after their release. Fertilized eggs sink into interstices of the gravel before absorbing water and then swell to about 4 times their initial size. Swelling lodges embryos in the gravel. Hatching takes place in 3–7 days at 15–22°C and larvae take another 3–4 days to become free-swimming. Young-of-year hitch spend the next 2 months shoaling in shallow water or staying close to beds of aquatic plants, especially among emergent tules, before moving out into more open water, at about 50 mm FL. In permanent streams and in ponds, larval and postlarval hitch aggregate around aquatic plants or other complex cover in shallow water. They are most active during the day (Moyle 2002).

Dispersal Capability: Only capable of natural colonization via hydrologic stream connection. Hitch have, however, been widely dispersed outside their native range via water delivery infrastructure, especially the California Aquaduct. The viability of these introduced populations is not known.

Habitat Requirements: 

Habitat Requirements: Sacramento hitch inhabit warm lowland waters, from clear streams, to turbid sloughs to lakes and reservoirs. In streams they are usually found in pools or in runs among aquatic vegetation, although small individuals will also use riffles. Usually they are in water Spawning takes place over gravel riffles, at temperatures ranging from 14° to 26° C, but spawning on vegetation can also take place (Moyle 2002). When floodplains are available, hitch will use them for rearing, although juveniles can become stranded once the floodwaters recede (Moyle et al. 2007).

Distribution: 

Distribution: Hitch were once found throughout the Sacramento and San Joaquin valleys in low elevation streams and rivers, as well as in the Delta. Today they are absent from the San Joaquin River and the lower reaches of its tributaries from Friant Dam down to the Merced River (Brown 2000, CDFG 2007). However, they have become established through introductions in a few reservoirs, such as Beardsley Reservoir (Stanislaus River, Tuolumne County), San Luis Reservoir (Merced County), and Bass Lake (Fresno County). From San Luis Reservoir, they have been carried by the California Aqueduct to southern California reservoirs, although it is not known if these populations are self-sustaining (Moyle 2002).
In the Sacramento River, they appear to inhabit much of their native range up to and including Shasta Reservoir, but populations are scattered (Moyle 2002). May and Brown (2002) found hitch only at a few localities, in relatively low numbers. They are present in some of the larger tributaries to the San Francisco Estuary (Leidy 2007) and in a few sloughs in the Delta (see next section).

Abundance Trends: 

Trends in Abundance: The changing abundance and distribution of Sacramento hitch is poorly documented but the evidence suggests they are much less abundant and widely distributed than they were formerly. Their populations are scattered among various streams, lakes, and reservoirs with few inter-connections. May and Brown (2002), for example, in a survey of Sacramento Valley streams, found hitch in small numbers at only a few valley floor locations. CDFG (2007) and Brown (2000) recorded no hitch in extensive sampling of the lower San Joaquin River. Leidy (2007) noted that hitch were present in 13 of 65 watersheds tributary to the lower San Francisco Estuary and “locally abundant” in only seven; all sites were heavily influenced by urbanization. In the Delta, once a major fish habitat, Brown and May (2006) recorded only 24 hitch from an eight year seining program that captured over 43,000 fish of all species. Moyle et al. (2007) captured only small numbers of hitch in a 5 year study of the fishes using the tidal sloughs and floodplain of the Cosumnes River and none in the river itself. Likewise, Nobriga et al. (2005) encountered only 174 hitch in a program that captured over 79,000 fish in the Delta. However, similar numbers were taken in extensive sampling of the Delta in 1961-62 (Turner 1966) suggesting little change in their minority status. Nevertheless, Brown and Michniuk (2007) compared electrofishing captures of native fish in the Delta between 1980-83 and 2001-2003 and found a general decline in native fishes, including hitch. They also found hitch seem to be largely confined to the northern Delta. Feyrer and Healey (2002) concluded that hitch had been extirpated from the southern Delta by the time of their study, 1993-94.

Description: 

Description: Hitch are deep-bodied, cyprinids with a terminal, slightly upturned mouth that can grow to over 350 mm SL. The body is moderately elongated and thick, almost oval shaped in cross section (Hopkirk 1973, Moyle 2002). The head is relatively small and conical. The caudal peduncle is narrow. Scales are fairly large, 54-62 along the complete, decurved lateral line. Sacramento hitch have 10-13 dorsal fin rays, 11-14 anal fin rays, and 17-26 gill rakers. The pharyngeal teeth are long, narrow, and slightly hooked, but the surfaces are relatively broad and adapted for grinding food (Moyle 2002). Young fish are silver and have a dark, triangular blotch on the caudal peduncle. As fish age, they become duller in color, with the dorsal area turning brownish-yellow (Moyle 2002).