The splittail (''Pogonichthys macrolepidotus''), also called Sacramento splittail, is a cyprinid fish native to the low-elevation waters of the Central Valley in California. It was first described by

William O. Ayres William Orville Ayres (September 11, 1817 – April 30, 1887) was an American physician and ichthyologist. Born in Connecticut, he studied to become a doctor at Yale University School of Medicine. Life and career Ayers, the son of Jared and D ...

in 1854. It is the sole living member of its genus, the

Clear Lake splittail The Clear Lake splittail (''Pogonichthys ciscoides'') was endemic to California's Clear Lake and its tributaries until its numbers severely declined due to competition from the introduced bluegill and alterations to the flow of inlet streams. In ...

''P. ciscoides'' having become extinct in the 1970s. The distinctive feature of the splittail is the larger upper lobe of the tail fin. It also has tiny barbels at the corners of the mouth. The dorsal fin has 9-10 rays, while the pectoral fins have 16-19 rays, the pelvic fin 8-9 rays, and the anal fin 7-9 rays. Color is silver on the sides, with a dusky olive gray on the back; during the breeding season the fins pick up a red-orange tinge, and the males become darker and develop white tubercles on the head and at the bases of the fins. They feed on bottom-dwelling invertebrates and detritus, generally in areas of low to moderate current. In

Suisun Bay Suisun Bay ( ; Wintun for "where the west wind blows") is a shallow tidal estuary (a northeastern extension of the San Francisco Bay) in Northern California. It lies at the confluence of the Sacramento River and San Joaquin River, forming the ent ...

, opossum shrimp (mostly ''Neomysis mercedis''),

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

s such as ''

Corophium ''Corophium'' is a genus of the amphipod family Corophiidae. Formerly a much larger genus, many species have been transferred to segregate genera such as '' Monocorophium'' and '' Crassicorophium''. Species ''Corophium'' contains 12 species, af ...

'', and copepods are favorite foods, while in the Sacramento Delta they eat clams, crustaceans, and insect larvae. During periods of high water levels (February/March), splittails will move into flooded areas to look for earthworms. The Sacramento splittail utilizes floodplain habitat for feeding and spawning, and depends upon floodplain habitat for spawning..

Range

Their range is the lower-elevation waters of the Central Valley, extending to

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from a ...

. Although once found as far north as Redding, they are now only rarely seen in the upper Sacramento River. They were once caught from southern San Francisco Bay and in Coyote Creek ( Santa Clara County), but are now restricted to the Sacramento Delta,

, and the lower parts of Sonoma Creek, Petaluma River and Napa River. They are tolerant of moderate levels of salinity and/or alkalinity.

Status

Splittail were reclassified as a species of special concern by the U.S. Fish and Wildlife Service on September 22, 2003 from their prior classification as threatened due to litigation. In 2010, the FWS found that the splittail did not warrant listing under the Endangered Species Act.U.S. Fish and Wildlife Service, Bay-Delta Fish and Wildlife Office. Sacramento Splittail https://www.fws.gov/sfbaydelta/EndangeredSpecies/Species/Accounts/SacramentoSplittail/SacramentoSplittail.htm The Central Valley's system of sloughs and backwaters maintained by annual flooding has greatly changed. The cause of the decline of this species is under investigation.

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

previously classified the splittail as endangered, but the status was downgraded to least concern in 2013.

References

* Peter B. Moyle, ''Inland Fishes of California'' (University of California Press, 2002), pp. 146–150 {{Taxonbar, from=Q2123607 Pogonichthys Endemic fauna of California Fish of the Western United States Freshwater fish of the United States Natural history of the Central Valley (California) Fish described in 1854