Steelhead Distribution

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 summary information indicating the earliest and latest year an observation has contributed to the documented presence on that segment. 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.

In 2006-2007 the observation and distribution datasets underwent a quality review, first by those who contributed the data, and then by the California Department of Fish and Wildlife.

The steelhead distribution GIS Layers were added to the CalFish Map Viewer and the datasets were provided for download from the CalFish Data Downloads page in August of 2007.

Newly compiled observation data were added and an updated Summer Steelhead Distribution dataset was published to CalFish in October 2009. The Winter Steelhead Distribution dataset was subsequently updated in December 2010 and June 2012.

Range datasets (see description on the "Anadromous Distribution" page) were added to CalFish for both Winter and Summer Steelhead in February 2011.

Project Contact:

Connie Shannon - PSMFC Data Management Specialist
Environmental Resource Information Services
California Dept. of Fish and Wildlife
2440 Athens Ave
Redding, CA 96001
(530)-225-2155
connie.shannon@wildlife.ca.gov