Get to Know a Species: The Southern California Steelhead

Southern California steelhead, a species native to southern California's rivers, creeks, and estuaries, were once prevalent, journeying from the coastal mountains' headwaters to the ocean's kelp forests. This fish was a food source and held cultural significance for local tribes, particularly within the Santa Monica Mountains. The Chumash, sharing over 7,000 years of history with the steelhead, felt a deep kinship with these creatures, underscoring the importance of their preservation.

Covering an extensive range of 11,580 square miles, Southern California steelhead populations extend from the Santa Maria River in San Luis Obispo County down to the Tijuana River at the U.S.-Mexico border. They are the southernmost steelhead population globally. Historical records, including photographs, oral histories, and surveys, reveal that these fish once flourished, particularly within Malibu Creek.

What Happened to Southern Steelhead?

For centuries, the Southern California steelhead roamed Southern California rivers until a stark decline led to their 1997 classification as a federally endangered species. Habitat degradation and the obstruction of their migratory paths have critically hindered their breeding and maturation processes. This environmental impact caused a dramatic reduction in their numbers, plummeting from annual runs in the tens of thousands returning adults to fewer than 500.

The 100-year old Rindge Dam has prevented southern steelhead from migrating Malibu Creek from headwater breeding pools to reaching the ocean. Photo credit: Bernard Yin.

Urban infrastructure and water development since the 1920’s has led to significant alterations to the steelhead's migratory corridors. Particularly with dams and water diversions in areas like Malibu Creek. These barriers have not only fragmented their habitat but also potentially threaten the steelhead's unique genetic makeup. The life cycle of the steelhead trout begins in freshwater, where they can either remain as rainbow trout or migrate to the ocean. Unlike salmon, which spawn once and then die, steelhead are capable of multiple spawning journeys. During their time in the ocean, they can grow larger and stronger to help with these difficult journeys. The distinct size and color differences between rainbow trout and steelhead underscore their unique life strategies.

The Challenges for Survival

In the Malibu Creek watershed, the struggle for survival is evident. Limited habitat connectivity below the dam restricts the full lifecycle of the southern steelhead. Biologists are concerned about the potential loss of ocean-going genetics in local rainbow trout populations. Approximately 15 miles of aquatic habitat upstream from the dam offer a glimmer of hope, with the Malibu Lagoon acting as a vital transitional zone supporting young steelhead's preparation for oceanic life.

Southern steelhead populations are in danger of extinction within the next 25-50 years due to anthropogenic and environmental impacts threatening their recovery.

The rapid decline of Southern steelhead populations in fragmented habitats emphasizes the need for rebuilding the resiliency of this impressive fish. The Malibu Creek Ecosystem Restoration Project aims to dismantle these obstacles by totally removing Rindge Dam. We can help Southern steelhead reclaim their historical habitat and take steps to ensure the species' survival. This project not only seeks to restore critical juvenile habitats but also aspires to re-establish Southern steelhead as a keystone species within the Malibu Creek watershed, honoring their remarkable journey and vital ecological role.

Aerial photograph of Malibu Creek’s stream-lagoon-ocean transitional zone. Photo credit: Bernard Yin.