striped bass and largemouth bass, which are introduced species in the Sacramento-San Joaquin Delta. Endangered status Historically, delta smelt were relatively abundant in the upper Sacramento-San Joaquin Estuary, with populations declining dramatically in the 1980s. They were listed as threatened by both federal and state governments in 1993, and sustained record-low abundance indices, prompted their listing as endangered under the California Endangered Species Act in 2010. Critical habitat was listed for delta smelt on December 19, 1994. Delta smelt are threatened with extinction due to anthropogenic alterations to their ecosystem, including urbanization, non-native species, water diversions, contaminants, and the conversion of complex tidal habitats to leveed channels. A survey in April 2015 found only one individual delta smelt. Although the fish is almost extinct in the wild, extant populations remain in a captive-breeding program at UC Davis and in a fish hatchery operated by the U.S. Fish and Wildlife Service near Shasta Dam. Court protection In 2005, the U.S. Fish and Wildlife Service (FWS) issued a biological opinion that the Central Valley Project and the California State Water Project were not having an adverse effect on the recovery of the delta smelt. The Natural Resources Defense Council sued, and in 2007, Fresno U.S. District Court Judge Oliver Wanger found the biological opinion was arbitrary and capricious and ordered protections for the delta smelt while the document was redone. In 2008, at the close of the court's deadline, the FWS issued a new biological opinion. This time, the FWS came to the opposite of its earlier conclusion, finding the water projects were jeopardizing the continued existence of the delta smelt. When six new plaintiffs sued, Judge Wanger preliminarily ordered the FWS to give him weekly justifications of delta flow restrictions and appointed four scientists as his own expert witnesses. After haranguing FWS expert witnesses as “zealots”, in December 2010 Judge Wanger, again, found the FWS BioOp was arbitrary and capricious and, again, ordered the FWS to complete a new one. In 2014, a divided panel of the Ninth Circuit Court of Appeals reversed Judge Wanger. While the new biological opinion was “a ponderous, chaotic document, overwhelming in size”, it was found not arbitrary and capricious. The Ninth Circuit affirmed that the water projects were jeopardizing the existence of the delta smelt, and given TVA v. Hill's command that endangered species must be saved "whatever the cost", Circuit Judge Jay Bybee opined