Native Rainbow Trout Sub-Population Expansion Plan

Written by


Dr. Sandra Jacobson

South Coast Regional Director


Megan Nguyen
Communications Associate

Protecting Anadromous Fish Populations

Southern steelhead represent the southern edge of the species’ range and are critically vulnerable to climate change. CalTrout’s project, the Native Rainbow Trout Project, will increase resiliency of native rainbow trout populations in Southern California and facilitate recovery of endangered southern steelhead.

The four high priority rivers targeted for restoring anadromous steelhead populations are the San Luis Rey, Santa Margarita River, San Mateo Creek and San Juan Creek.

As part of the South Coast Steelhead Coalition (SCSC), CalTrout is working to ensure anadromous fish populations can successfully migrate between the ocean and freshwater habitats.

Connecting these steelhead populations to each other and to the ocean will strengthen the regional population network and increase resiliency of the species.



Level of concern for southern steelhead: CRITICAL. Click the image to learn more about what this score means.


Southern steelhead populations are in danger of extinction within the next 25-50 years due to anthropogenic and environmental impacts threatening their recovery such as major dams and fish passage barriers, urbanization, and estuary alteration. (SOS II: Fish in Hot Water Report)

A growing threat for these sensitive species is fire as seen with the Holy Fire in August 2018 which burned a total of 23,000 acres in Orange and Riverside Counties. The fire burned Coldwater Canyon, which held one of two remaining native rainbow trout populations of steelhead descent left in this part of Southern California.

Most of the trout survived the intense fire and were relocated to a regional hatchery for short-term safety. However, a long-term plan for relocating these rare and special native trout as they face a similar situation remains to be developed. There are only a handful of places that have all the needed characteristics.

Photo: Kerwin Russell (RCRCD).

While historically wildfires have a long term positive impact for salmon, “Changes in the frequency and intensity of wildfire combined with a general loss of population diversity across the landscape may inevitably, create a phenomenon where salmonids lack the tools to recover and ultimately adapt to the new wildfire regime we are currently witnessing California.”

Holy Fire burn area. Photo: Google Maps


Photo: AFP


Southern California Steelhead. Photo: Mark Capelli


In addition to re-establishing anadromous populations, efforts to maintain and expand existing native resident rainbow trout populations is also important.

These land-locked populations in Southern California are the remnants of steelhead runs over 100 years earlier.

They were identified by molecular genetic analysis by a study completed in 2014, and are recognized as the last remaining genetics sources of these historical salmonid populations.

There are new methods by which managed breeding of these highly valuable populations can be performed largely in the wild to avoid hatchery effects.

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