Delta Smelt

Delta Smelt: Life History and Decline of a Once Abundant Species in the San Francisco Estuary

Peter Moyle, Larry Brown, John Durand, James Hobbs

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Key points:

  • We now know more about Delta smelt than any other fish in the system, but this knowledge has not prevented the species’ trajectory towards extinction.
  • The Delta smelt is adapted to an ecosystem that no longer exists.
  • There is no “smoking gun”. The proximate causes of the decline are interactions among multiple factors that have altered their habitat, making it increasingly unsuitable.
  • The population exhibited some resilience when in 2011 environmental conditions were good and abundance was near historic levels, but unfortunately the current drought may have eroded such resilience.
  • The continued decline of Delta smelt demonstrates the general failure to manage the Delta for the “co-equal goals” of maintaining the Delta as a healthy ecosystem while providing a reliable water supply for Californians.