Pinto abalone at the hatchery
Introduction & Motivation
The pinto abalone (scientific name Haliotis kamtschatkana) is an endangered marine snail found along the Pacific coast of North America, from Mexico to Alaska. Due to a combination of overharvesting, habitat loss, disease, and other threats, all seven North American abalone species are now threatened, with the pinto abalone being the widest-ranging. Despite decades of fishery closures, most populations have only recovered slightly. In Washington, numbers are at only 3% of what they were before the fishery closed (when they were already depleted). Since 2009, nearly 26,000 hatchery-raised juvenile abalone have been outplanted at restoration sites in the San Juan Archipelago as part of recovery efforts. While current restoration uses locally collected wild abalone as broodstock, finding these animals has become increasingly difficult due to severe population declines.
As part of our Wild Genomes Marine program launched in 2021, Revive & Restore funded Dr. James Dimond at Western Washington to examine the connectivity of pinto abalone populations across their entire 3,700 km range. A primary motivation for this study was to support ongoing restoration efforts in Washington state. Dimond and his colleagues set out to determine if broodstock from outside Washington could be safely sourced without risking genetic problems. This required understanding the genetic structure across the species’ entire range to weigh the risks of inbreeding (from limited local broodstock) against the risks of outbreeding (from introducing genetically different individuals from distant populations).
A new publication in Evolutionary Applications details the team’s key findings, which include:
Key Findings
- One Connected Population: Despite being spread across a vast geographic range, pinto abalone function essentially as a single genetic population. Scientists call this pattern “panmixia,” meaning there is high gene flow throughout the species’ range.
- High Genetic Health Despite Low Numbers: Even though their populations have been severely depleted, pinto abalone have maintained high genetic diversity with no evidence of a genetic bottleneck.
- Slight Differences in Protected Waters: The only areas showing slight population differences were in the Salish Sea (Washington/British Columbia) and Inside Passage regions, which appear to have higher barriers to dispersal compared to outer coastal areas.
- Ancestral Range Identified: The north-central region (from Southern Oregon to Revillagigedo Island in Alaska) likely represents the original range of the species, with populations at the northern and southern extremes representing later expansions.
- No Evidence of Local Adaptation: The researchers did not find evidence of genetic adaptation to local conditions, suggesting limited adaptive differentiation across the range.
Conservation Implications
These findings have important implications for ongoing restoration efforts by addressing a critical decision point: whether to risk continued inbreeding by using the limited remaining local broodstock, or to introduce broodstock from outside populations. Since the study shows that pinto abalone are essentially one genetic population, it provides strong evidence that conservation programs could source breeding stock from anywhere within the species’ range without negatively impacting the evolutionary history of local populations.
The study highlights that while genetic connectivity is high across the range, this doesn’t mean that depleted populations will quickly recover on their own. Even with genetic connectivity, the actual number of individuals moving between areas may be too small to rebuild populations within a timeframe that matters for conservation. This justifies continued restoration efforts, particularly in areas like the Salish Sea where barriers to natural dispersal are higher.
The Washington State restoration program has been transitioning from a small-scale pilot to a larger production phase with multiple satellite hatchery facilities. The results from Dr. Dimond and his colleagues provide critical guidance for sourcing diverse broodstock as the program scales up its efforts to reestablish self-sustaining populations of pinto abalone in the wild.
Going forward, Dr. Dimond looks forward to leveraging these results to inform restoration work conducted by the Puget Sound Restoration Fund and other local partners. He also expressed excitement about honing in on sperm cryopreservation methods for pinto abalone, which have been attempted but need refining. Given the species’ protected status, he says that dealing with cryopreserved sperm rather than whole animals would allow scientists to produce offspring more efficiently and conduct assisted gene flow to foster genetic diversity and accelerate adaptation.
Revive & Restore is proud to have supported this important research, and we look forward to following how it contributes to restoration activities for pinto abalone in Washington and beyond.
