Longfin Smelt
Like their cousin, the delta smelt, longfin smelt used to be one of the most common fishes in San Francisco Bay. 

For most of their two-year life span, longfin smelt prefer saltier water than delta smelt: they can be found throughout the estuary and, sometimes, in coastal water outside the Golden Gate. Longfin smelt also migrate upstream in the winter to spawn in the Delta, where they are also harmed by the effects of water project operations. 

Longfin smelt are particularly dependent on strong freshwater flows into the Bay during the springtime, flows that have been substantially reduced in most years by storage and diversion of water on nearly all of the bay’s tributary rivers. Today, the abundance of longfin smelt is less than 2% of levels measured just ten years ago and less than 1% of average levels measured in the 1970s and 1980s.
 
In 2007, The Bay Institute in collaboration with the Center for Biological Diversity and the Natural Resources Defense Council, petitioned the U.S. Fish and Wildlife Service and California Department of Fish and Game to list the longfin smelt under the federal and state Endangered Species Acts. 

After designating longfin smelt a candidate species in 2008, the California Fish and Game Commission listed the species as “threatened” in 2009. In contrast, the U.S. Fish and Wildlife Service denied the listing petition. 

The Bay Institute and the Center for Biological Diversity challenged this decision in court and in February of 2011, a federal district court approved required the agency to reevaluate whether federal Endangered Species Act protection is needed for the longfin smelt. The Service has agreed to complete a rangewide status review of the longfin smelt and make a new determination on whether Endangered Species Act protection is warranted by March 31, 2012. The Service will also consider whether the Bay-Delta or any other longfin smelt population from California to Alaska qualifies as a “distinct population” that warrants federal protection.

Longfin smelt population, 1967-2010