Few issues in the Delta are as clear cut as predation. Larger predator species eat smaller fish with potential devastating impacts on native endangered species such as salmon and smelt.

Predation Facts (landscape)

Nonnative species pose a particularly significant predation threat in the estuary. Many of these predators were planted in the Delta for sport and recreational fishing purposes, with little concern for the native species they now endanger such as salmon, delta smelt and steelhead.

Exacerbating the problem, it has long been the State’s misguided policy to protect and maintain the populations of these predators through the use of size and bag limits. Fish stocking programs have also been utilized in the past to increase the adult populations of these voracious feeders.

Many species that are nonnative to the Delta have direct or indirect impacts on native threatened species, which greatly reduces survival of native fishes. Striped bass represent a direct predatory threat to the delta smelt and salmon and yet are protected by an ongoing California Department of Fish and Game program that maintains the population at artificially high levels to the detriment of native species. Until 1992, the Department restocked striped bass as part of an active population management program.


  • Coalition Efforts - In 2008, the Coalition filed a lawsuit in federal district court against the Fish and Game Commission and the Department of Fish and Game for violating the federal Endangered Species Act.
  • Methods by Other States - Predation issues, like those experienced in the Delta, are not exclusive to California. Neighboring western states face similar drought conditions as California and and are also home to endangered fish species, not unlike those in the Delta.

Visit our Striped Bass  page and read Delta Watch for additional information on  non-native fish predation.