5-Year Review : Summary and Evaluation of Southern California Coast Steelhead Distinct Population Segment

West Coast salmon and steelhead (Oncorhynchus spp.) stocks have declined substantially from their historic numbers and many are now listed as threatened or endangered. Multiple factors have contributed to the decline of individual populations. These include the loss of freshwater and estuarine habitat, periodic poor ocean conditions, and a variety of land-use, flood control, and water management practices which have impacted many watershed-wide processes; these include hydrologic and sedimentation processes which create and maintain essential steelhead habitats. These factors collectively led the National Marine Fisheries Service (NMFS) to list southern California steelhead (the anadromous form of O. mykiss) as endangered under the ESA in 1997.