CNDDB News Blog

Longfin smelt photograph by Bill Stagnaro(opens in new tab) (CC BY-SA 3.0(opens in new tab)) from Mare Island, Solano County, California

Longfin smelt (Spirinchus thaleichthys) are relatively small (10-20 cm) anadromous fish with characteristically long pectoral fins that can be found in middle or deeper parts of the water column of estuaries and bays from California to Alaska. Longfin smelt were listed throughout their range in California as Threatened under the California Endangered Species Act in 2009. Recently, due to ongoing threats from altered hydrology, nonnative species, and effects of climate change, the U.S. Fish and Wildlife Service (USFWS) ruled that the San Francisco Bay-Delta distinct population segment (DPS) of the longfin smelt is Federally Endangered (effective 29 August 2024).

Because different populations in California now have different legal status, CNDDB has added a new species record for the Bay-Delta DPS and split our Element Occurrence records based on these populations. The following are our two species records representing this taxon along with their general distribution based on the USFWS’s recent descriptions and map figures:

• Longfin smelt (Spirinchus thaleichthys)
  • State Threatened
  • Coastal estuaries north of the Russian River (primarily Humboldt Bay) and south of Pillar Point, Half Moon Bay.
• Longfin smelt - San Francisco Bay-Delta DPS (Spirinchus thaleichthys pop. 2)
  • State Threatened
  • Federally Endangered
  • Gulf of the Farallones from Russian River to Pillar Point, Half Moon Bay, and salt and freshwater habitats upstream of the Golden Gate including the San Francisco Bay, Sacramento - San Joaquin River Delta, and their tributaries where found.

References

• California Natural Diversity Database (CNDDB). July 2024. State and Federally Listed Endangered and Threatened Animals of California(opens in new tab). California Department of Fish and Wildlife, Sacramento, CA.
• U.S. Fish and Wildlife Service. 2024a. Endangered Species Status for the San Francisco Bay-Delta Distinct Population Segment of the Longfin Smelt, Final Rule(opens in new tab). Federal Register 89(146):61029-61049.
• U.S. Fish and Wildlife Service. 2024b. Species Status Assessment for the San Francisco Bay-Delta Distinct Population Segment of the Longfin Smelt(opens in new tab). Version 2.0. U.S. Fish and Wildlife Service. San Francisco Bay-Delta Fish and Wildlife Office, Sacramento, California. 105 pp. + Appendices A–E.