Could Black Abalone Return En Masse to the California Coast? With a Trial Translocation from the Channel Islands, Scientists Aim to Find Out

The habitats protected by the National Park Service (NPS) serve as a refuge for numerous species that struggle to exist in a developed landscape. Even in the ocean, our protected park spaces serve as a refuge for species. Since the middle of the 20^th century, development of the California coastline has exploded and these areas are now home to millions of people. Prior to this era, the coastlines were dominated by a different species, black abalone (Haliotis cracherodii). Ask anyone who grew up in coastal California in the mid-20^th century and they will tell you that during any visit to the rocky shores, you’d encounter black abalone…and a lot of them!

Since the middle of the 20th century, development of the California coastline has exploded and these areas are now home to millions of people. Prior to this era, the coastlines were dominated by a different species, black abalone.

NPS / Michael Ready

Black abalone are considered a keystone species in the rocky intertidal zone meaning they play a significant role in the health of the ecosystem. In addition to being ecologically valuable, historically the species is known to have been an important food source for humans. As our economy and ability to extract resources grew, black abalone populations began to dwindle. Still, given the species’ ability to prolifically reproduce, it was considered an inexhaustible resource. But that, unfortunately, turned out to be wrong.

In the late 1980s, a devastating disease called withering foot syndrome spread through the entire population which further reduced the population. By 1993, black abalone populations were so diminished that commercial and recreational fisheries were closed. In 2009, the US Fish and Wildlife Service listed black abalone on the endangered species list. Mainland populations were virtually non-existent and remain so today. However, in small pockets, black abalone populations hung on. The isolation and protection of Channel Islands National Park provided a refuge for black abalone to weather the dual storm of over-exploitation and disease. The diminished populations of abalone slowly began to increase off the Channel Islands in the cold surrounding waters, which are known to limit the spread of withering foot syndrome.

While the population is far from where it used to be, we are now seeing the highest numbers of black abalone observed in many years—a good sign for the recovery of this critical intertidal species. In fact, there are enough abalone present that marine ecologists believe that we can begin moving small portions of the Channel Island’s population to the mainland where black abalone have been absent for decades.

In 2023, a team of scientists and managers from the National Oceanic and Atmospheric Administration, the National Park Service, The Nature Conservancy, California Department of Fish & Wildlife, the University of California-Santa Cruz, and the University of California -Santa Barbara began the work of transporting 100 black abalone from the Channel Islands to the mainland of Central California. For the next year, the team will track and monitor each one of these individuals to document the efficacy of the move. If deemed successful, an additional 100-200 abalone will be added to the new mainland population in hopes of building a long-term, sustainable population.

The Southern California Research Learning Center is boosting this effort through support for the development of eDNA monitoring protocols, which would allow scientists to detect the presence of cryptic species like the black abalone through discovery of discarded genetic material in water samples. We are also working with our partners to create a comprehensive science communication project that will document the journey of this species and the incredible story of partnerships required to bring it back to its once glorious state.

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A Publication of the Southern California Research Learning Center

The Southern California Research Learning Center is one of 18 Research Learning Centers across the country. These centers strive to increase scientific activity in the national park system, to communicate research that supports stewardship and to make science part of the visitor experience. By working with a variety of partners, we aim to support science-based decision-making, increase science literacy and promote a conservation ethic within the Santa Monica Mountains National Recreation Area, Channel Islands National Park, and Cabrillo National Monument.