As part of our Wild Genomes Marine program, Revive & Restore funded Dr. James Dimond at Western Washington to examine the connectivity of pinto abalone populations across their entire 3,700 km range. Dimond set out to determine if broodstock from outside Washington could be safely sourced without risking genetic problems. This required understanding range-wide genetic structure to weigh the risks of inbreeding (from limited local broodstock) against the risks of outbreeding (from introducing genetically different individuals from distant populations). To investigate this, the team used reduced representation sequencing (RADseq) to generate single nucleotide polymorphism (SNP) data in samples taken from Alaska to Mexico. 

A new publication in Evolutionary Applications details the team’s key findings, which include:

1. 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.
2. Although their populations have been severely depleted, pinto abalone have maintained high genetic diversity with no evidence of a genetic bottleneck.
3. 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.
4. 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.
5. The researchers did not find evidence of genetic adaptation to local conditions, suggesting limited adaptive differentiation across the range.

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.