Native Rainbow Trout Subpopulation Expansion Plan

Native Rainbow Trout Subpopulation Expansion Plan

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Project Goal:

The management of non-native aquatic species addressees a major threat to the survival of native trout. Management is arduous and expensive, but worth the long-term investment to clear prime habitat of exotic species and make way for natives.

Increased native rainbow trout numbers, decreased non-native aquatic species such as bullhead

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Estimated Completion Date:


Fish Affected:

Project Description

At the southernmost end of California's South Coast, the four high priority rivers targeted for restoring steelhead populations are the San Luis Rey, Santa Margarita River, San Mateo Creek and San Juan Creek. Establishing anadromous populations that successfully migrate between ocean and freshwater habitats is the major emphasis of the South Coast Steelhead Coalition (SCSC). Connecting these steelhead populations to each other and to the ocean will strengthen the regional population network and increase resiliency of the species.

CalTrout is leading the SCSC in the Native Rainbow Trout Sub-population Expansion Project Plan. The project's goal is to increase the genetic and geographic diversity of native rainbow trout and facilitate recovery of endangered Southern California steelhead.

This will be achieved by transporting native trout as embryos into suitable habitat and using breeding methods that maximize genetic diversity. The end goal is not to maximize trout numbers, but to create stable and small populations in geographically dispersed areas. This will serve as an ecological risk mitigation from sporadic local extinction caused by severe environmental changes such as fire, drought, water quality or quantity alterations, non-native species competition, climate change and disease. Two native rainbow trout populations of steelhead descent in Coldwater Canyon Creek and the West Fork San Luis Rey River will be used as founder populations. These populations are upstream of dams that block their connection to the ocean and to each other. This naturally maintained and isolated community can be used as a genetic source that can be further crossed with other Southern California native rainbow trout to populate other suitable habitats in neighboring watersheds.

In 2019, CalTrout began project planning and development, and is working on a path forward for project funding.

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