Press Release
Bay-Delta longfin smelt population falls short of test for federal protection, U.S. Fish and Wildlife Service to continue evaluating status of rangewide population

April 8, 2009



The U.S. Fish and Wildlife Service (Service) today announced that the Bay-Delta population of longfin smelt does not meet the legal criteria for protection as a species subpopulation under the Endangered Species Act (ESA).

The Service simultaneously announced that it is seeking additional information for a broader assessment of the longfin smelt that could lead to future action, although no decision can be made before reviewing any new information.

The Service determination came in response to a petition seeking protection under the ESA as a distinct population segment (DPS) for only the longfin smelt population in the Bay-Delta. Longfin smelt live in estuaries along the Pacific Coast from the Bay Area to Alaska.

The Service explained that, because some Bay-Delta longfin smelt migrate into the Pacific Ocean and can travel up the coast to breed with longfin further north, they fail to meet the criteria for protection as a DPS. Under existing policy, for designation as a DPS the population segment must be “markedly separated from other populations” of the species.

To list the species as petitioned, the Service “must first consider discreteness of the population segment in relation to the remainder of the species.” But “based on the best scientific and commercial information available, the San Francisco Bay-Delta population of the longfin smelt is not markedly separated from the other populations,” the Service found, and therefore it could not designate the Bay-Delta longfin smelt as a DPS.

The 2007 petition specifically asked to list as a DPS only the population that lives in Bay-Delta. The petition asserted that the Bay-Delta longfin smelt are physically isolated, genetically different, and live in a unique setting.

In reaching its 12-month finding, the Service determined that: 1) a portion of the Bay-Delta longfin smelt population regularly disperse into the Pacific Ocean; 2) coastal currents can disperse them to estuaries further north, including Humboldt Bay; 3) based on the existing scientific information a conclusion could not be reached that the longfin smelt in the Bay-Delta are markedly separate from other populations; and 4) the single genetic study available is too limited to show that Bay-Delta longfin smelt are genetically different from other longfin.

Longfin smelt is an anadromous species, up to 5 inches long, that tolerates wide ranges of salinity. It generally has a two-year life cycle, spawning from November to June in the Sacramento River and down to Suisun and San Pablo bays, which are the principal nurseries for larvae. Longfin smelt indices in the Delta have been low since 2000.

A 1992 petition sought to list the entire longfin smelt population, but the Service determined in 1994 that the population of the entire species did not warrant protection.

Another Delta species, the delta smelt already is protected under the ESA as “threatened.” Delta smelt do not swim as well as the longfin and are found exclusively in Delta waters. Recent survey data for both species show record and near-record lows.

The broader longfin smelt assessment will look at the species throughout its range: Alaska, British Columbia, Washington, Oregon, and California. The Service is requesting information regarding: taxonomy, genetics, distribution, habitat selection, population density and trends, habitat trends, effects of management, dispersal and migratory capabilities or patterns of dispersal, and potential threats to the longfin smelt.

Comments and information for the larger longfin smelt assessment should be directed to: Field Supervisor, U.S. Fish and Wildlife Service, 2800 Cottage Way, W-2605, Sacramento, CA 95825; telephone 916-414-6600; fax, 916-414-6712. There is no deadline for submission of information.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals and commitment to public service. For more information on our work and the people who make it happen, visit


The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals, and commitment to public service. For more information on our work and the people who make it happen, visit www.fws.gov.

For more information on our work and the people who make it happen, visit http://www.fws.gov/. Connect with our Facebook page, follow our tweets, watch our YouTube Channel and download photos from our Flickr page.