Pacific Southwest Region
California, Nevada and Klamath Basin

Longfin Smelt 12-Month Finding

San Francisco Bay-Delta Population of Longfin Smelt is in Need of Protection, But Will Not be Immediately Considered for Listing as an Endangered Species

The Service has found that the San Francisco Bay-Delta Distinct Population Segment (DPS) of longfin smelt warrants consideration for protection under the Endangered Species Act (ESA), but the Service is precluded at this time from drafting a formal listing rule by the need to address other higher priority species.
The finding, which was made after a comprehensive review of the best available scientific information concerning the species and the threats it faces, means the longfin smelt DPS will be added to the list of candidates for ESA protection, where its status will be reviewed annually. Candidate species do not receive statutory protection under the ESA, meaning that today’s finding does not impose any new requirements or restrictions. View the News Release

Longfin Smelt 12-month finding (Full version, PDF, 1MB)
Longfin Smelt 12-month finding questions and answers (PDF)

The Finding will be published in the April 2, 2012, edition of the Federal Register.

what is a candidate species?

Candidate species do not receive statutory protection under the ESA. However, the annual review and identification of candidate species provides the Service and other federal agencies, states, tribes, and other partners and stakeholders with notice of species in need of conservation, allowing them to address threats and work to preclude the need for protection under the ESA. Addressing the needs of candidate species before the regulatory requirements of the ESA come into play often allows greater management flexibility to stabilize or restore these species and their habitats. As threats are reduced and populations increase or stabilize, attention can be shifted to those candidate species in greatest need of the ESA’s protective measures. Any future proposal to add longfin smelt to the federal list of threatened and endangered species would be subject to public review and comment.

About longfin smelt

The historical and current range of the longfin smelt extends from Alaska southward to the San Francisco Bay-Delta in California, which includes the Delta, Suisun Marsh, San Pablo Bay, and the San Francisco Bay to the Golden Gate Bridge. The range is made up of at least 20 scattered populations found in estuaries, rivers, and lakes stretching from California to Alaska.

Juvenile Longfin Smelt. BOR Photo

The longfin smelt is a pelagic (lives in open water) estuarine fish that typically measures 3.5 to 4.3 inches standard length, although third-year females may grow to almost 6 inches. Longfin smelt can be distinguished from other smelts mainly by their long pectoral fins. The Service found that listing the longfin smelt is warranted only for the Bay-Delta, not range-wide.

Large distances between populations, the small size of this fish and potential obstacles to movement in the form of ocean circulation patterns make the Bay-Delta population of longfin smelt markedly separate and therefore discrete from other longfin smelt populations. At the time of the last 12-month finding (April 9, 2009), the Service did not have information available assessing the potential for the longfin smelt to disperse to other estuaries via ocean currents. Since that previous finding, the Service convened an independent expert panel to review additional information on ocean circulation in nearshore waters and over the continental shelf from approximately Monterey Bay north to the Klamath River. Numerous studies provide evidence that ocean currents present obstacles to southerly movement from northern estuaries to the San Francisco Bay-Delta. Longfin smelt were historically one of the most abundant pelagic fishes in the San Francisco Bay-Delta.

However, their numbers have declined significantly in recent years. While no statistically valid estimate of abundance currently exists for longfin smelt, relative abundance can be inferred from data collected by various fish monitoring surveys. Abundance indices derived from survey data all show marked declines in Bay-Delta longfin smelt populations, particularly for the years 2002-2009. These surveys collectively indicate that longfin smelt abundance over the last decade (2000-2010) is the lowest ever recorded in the surveys’ 40-year history.