Small Populations in Jeopardy: A Delta Smelt Case Study

Under § 7 of the federal Endangered Species Act (ESA or the Act),'federal agencies must ensure that actions they authorize, fund, or carry out are" not likely to jeopardize the continued existence of any endangered species or threatened species or result in the destruction or adverse modification of habitat of such species." 2 For species with low and declining populations, applying this standard is legally and scientifically difficult. 3 The US Fish and Wildlife Service (FWS) faced this problem in its recent biological opinion (BiOp) analyzing impacts to threatened Delta smelt from water project operations in the California Delta. FWS concluded the" species' recent abundance trends strongly suggest it is in the midst of demographic collapse," and most recent surveys to locate smelt have failed to find them.'Nevertheless, FWS approved agency actions that will likely increase extinction risk for Delta smelt.