Background
Due in large part to a restriction in range and a loss of habitat, naturally spawning populations of steelhead salmon in California have declined precipitously in recent years.  This has led to steelhead being federally listed as Endangered in Southern California, and Threatened along the Central Coast and Central Valley.  The economic, social, and cultural importance of steelhead, coupled with their decline in numbers and subsequent listing has led to a great deal of research and effort aimed toward recovery and restoration.  The statewide steelhead distribution is the result of a cooperative effort to provide resource management agencies the information they need to make species management and recovery planning decisions.

This project was largely funded by the NOAA National Marine Fisheries Service.  It was designed, supervised, and partially funded by the CDFG.  The Pacific States Marine Fisheries Commission provided project management and technical assistance.  This project brought together the knowledge and expertise of biologists and trained observers throughout the state.  Prior to this effort, there was no consistent, statewide distribution data for Steelhead. We believe that this dataset will be extremely useful for effective long-term management of this species.

Method
As with the coho distribution project, no new field data were collected.  The distribution was developed from existing field observation data and distribution data that were contributed by a variety of government, private, and tribal agencies.  A point dataset (shapefile) was created from all of the observations that could be located on a map.  The resulting dataset named the source of the data and included details regarding the observation such as the observers' name, agency affiliation, and the date.  This point dataset was then used to develop two distribution datasets, one for summer steelhead, and one for winter steelhead.

The distribution stream linework was developed by tracing downstream from each observation to the sea.  For this process, we used the flow properties of USGS National Hydrography High Resolution Dataset (hydrography at a scale of roughly 1:24,000).  The process of tracing to the sea from these observation locations assumes that if anadromous steelhead are observed at a point along a stream, then they may also be found at any point downstream from there.

Once the linework was drawn, sections of stream were assigned a value of either Anad Present (Anadromous present), Anad Suspected (Anadromous suspected), or Unsp Present (Unspecified O. mykiss present) depending upon the observations recorded above.  An example of Unspecified present would be when juvenile trout were observed and it was not known whether the fish were of anadromous or resident origins.  Summary data were also included with the linework to indicate how many observation points were recorded in the waters above each stream section.  The end result is a set of lines representing the distribution of steelhead based on the various observations in the point dataset.

Project Status

• We began to pull steelhead observation data together in February 2005. The first draft distribution was completed in fall of 2005.
• During spring and summer of 2006 there was an additional effort to acquire and compile observation data along California's Southern Coast.
• The observation and distribution datasets are currently undergoing a quality review, first by those who contributed the data, and then by the California Department of Fish and Game.
• Our plan is to add the steelhead distribution GIS Layers to the CalFish Map Viewer and to provide the complete dataset for download from the CalFish Data Downloads page.  Expected timeframe for publication is August of 2007.
• We intend for this to be an ongoing and ever-improving dataset.  We anticipate continuing to collect observation-based datasets and further refinement of the distribution layer.  Please contact us if you have information that you would like us to include.

Project Contact:
Connie Shannon - PSMFC Data Management Specialist

Information Services Branch
California Dept. of Fish and Game - 2440 Athens Ave.
Redding, CA 96001
(530)225-2155  cshannon@dfg.ca.gov