Chi Council for the Clear Lake Hitch

Probable Causes for the Decline in the Clear Lake Hitch
Population from 1950 to the Present

 

1. Loss of spawning habitat:

  1. Gravel mining and channeling of major creeks in the 1950's and 60's lowered and removed gravel spawning beds and impaired hitch access to smaller tributaries
  2. Rock weirs constructed to protect the footings of bridges on Kelsey, Scotts and Middle creeks block hitch migration to about 30 miles of historic spawning beds on those creeks.
  3. Other physical barriers across streams such as low water crossings, dams and culverts impair or obstruct hitch migration to historic spawning beds.

2. Competition in Clear Lake from non-native species:

  1. Inland silversides introduced into Clear Lake in the mid-1960's to combat the Clear Lake gnat compete with hitch for the same zooplankton food source. This fish has enormous population explosions and die-offs. They are thought to have contributed to the ultimate extinction of the endemic Clear Lake splittail (called chi in the Pomo language) that occurred by the middle 1970's.
  2. Threadfin shad introduced into Clear Lake in the mid-1980's as a bait fish compete with hitch for the same zooplankton food source. The threadfin shad eliminate Daphnia, a principal food of hitch, from the plankton. This fish, like the inland silverside, experiences enormous population explosions and die-offs.
  3. Florida strain of largemouth bass introduced in the mid-1960's prey aggressively on hitch, especially when hitch aggregate near the mouths of the creeks during the spring spawning season.

Sources: Peter B. Moyle, Inland Fishes of California (2002), pgs. 136-139; Samuel M. McGinnis, Field Guide to Freshwater Fishes of California (2006), pgs. 208-209; personal observations of author and other Chi Council observers. The proper use of the term "chi" to refer to the Clear Lake splittail was explained to the author by Nelson Hopper, a native speaking Pomo elder at Big Valley Rancheria. The Pomo word for hitch is "hitch."

 

Dated: April 21, 2009
Peter F. Windrem

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