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 1530 cm by the end of the second year; when they mature. Subsequent increases are 2050 mm/year, with a maximum size of around 35-40 cm. Hitch in Beardsley Reservoir, in contrast, are only 4050 mm FL by the end of the first year and 911 cm FL by the end of their second, with subsequent increments of 2040 mm/year. In Putah Creek they average about 65 mm FL at the end of their first year and reach 200250 mm in 34 years. Females grow faster and larger than males. Scale analysis indicates that hitch live 46 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 3,00026,000 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 15 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 37 days at 1522°C and larvae take another 34 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.