CLEAR LAKE HITCH: Lavinia exilicauda chi
DESCRIPTION: Clear Lake hitch are fairly large minnows with an average length of 13 inches and weight of 15.5 ounces. They have laterally compressed bodies, small heads, upward-pointing mouths, moderately large scales, and a large forked tail. Small hitch are silvery with a black spot at the base of the tail. Older fish lose the spot and become darker. Large fish appear yellow-brown to silvery white on the back.
HABITAT: Clear Lake hitch spawn in low-gradient tributary streams to Clear Lake, mostly in shallow riffles, runs, and backwater areas with clean, fine-to-medium gravel and water temperatures from about 57–64 degrees Fahrenheit. Hitch require resting pools that are found in healthy instream habitat. Adult hitch are usually found in the limnetic zone of Clear Lake. Juveniles require vegetated nearshore shallow-water habitats before moving into deeper offshore areas.
RANGE: Clear Lake hitch are endemic to Clear Lake and its tributary streams, in Lake County, California.
MIGRATION: Hitch migrate into tributary streams to spawn. Adults return to Clear Lake post-spawning and larval fish move quickly downstream to the lake within a couple weeks of hatching.
BREEDING: Spawning occurs from mid-March through May and occasionally into June. Each female is pursued by one to five males that fertilize the eggs as they are released. Females lay an average of 36,000 eggs.
LIFE CYCLE: Hitch embryos hatch out of their eggs after approximately seven days, and the larvae become free-swimming after another seven days. Larval fish must move downstream to Clear Lake quickly before streams dry up. In the lake, larvae remain inshore and are thought to depend on stands of tules for cover until they reach approximately 2 inches and assume a pelagic lifestyle. Males reach breeding age in their first or second year, while female hitch become mature by their second or third year. Adult hitch migrate up tributary streams to spawn in the spring to begin the life cycle again.
FEEDING: Adult hitch are open-water feeders that almost exclusively eat Daphnia — small, planktonic crustaceans known as “water fleas.” Juveniles feed primarily on the larvae and pupae of chironomid midges and planktonic crustaceans in the shallower nearshore environment.
THREATS: Water diversions, loss of spawning habitat and nursery areas, migration barriers that block passage to spawning grounds, alteration of creek habitat, in-channel mining, predation by and competition from introduced invasive fish, the impacts of pollutants, climate change and drought.
POPULATION TREND: Spawning numbers of hitch have gone from estimated millions historically, to hundreds of thousands in the 1970s, to the low tens of thousands through the 1990s, to the low thousands today.