The survival of hatchery‐origin pinto abalone Haliotis kamtschatkana released into Washington waters

In Washington State, the pinto abalone (Haliotis kamtschatkana) has declined by 97 percent since 1992 and is unlikely to recover without intervention. A captive rearing and restocking pilot study shows promise for saving wild populations from local extinction.

Interior shell of pinto abalone (Haliotis kamtschatkana). Photo: James St. John (CC BY 2.0)
Interior shell of pinto abalone (Haliotis kamtschatkana). Photo: James St. John (CC BY 2.0)

Captive rearing and restocking could help save wild populations of pinto abalone (Haliotis kamtschatkana) from local extinction. In Washington State, the species has declined by 97 percent since 1992 and is likely to disappear without interventions. Scientists produced juveniles in a hatchery from wild broodstock collected from the San Juan Islands. Once planted in the wild, the hatchery-reared juveniles grew to reproductive size and enough survived to create viable aggregations for spawning. Results of the pilot study will inform the production phase of the recovery effort, moving closer toward the goal of state-wide restoration. The findings and recommended changes to the abalone restoration program were published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems in 2019. The research was conducted by the Washington State Department of Fish and Wildlife and the Puget Sound Restoration Fund in partnership with the National Marine Fisheries Service, University of Washington, Western Washington University, American Indian tribes, the SeaDoc Society, and the Skagit County Marine Resources Committee.


  1. Wild populations of pinto abalone (Haliotis kamtschatkana) in Washington State have declined by 97% since 1992, despite a fishery closure since 1994. No recruitment has been detected recently, indicating probable reproductive failure due to low densities. A pilot programme placed a total of over 11,000 hatchery‐origin juveniles, age 18–22 months, at 10 sites in the San Juan Islands.
  2. Observed (naive) year 1 survival averaged 10.2% (0–23% range) and was most influenced by site compared with lineage or size‐at‐outplant. Families survived in the approximate proportions that they were outplanted, and there was little support for an effect of size‐at‐outplant on survival.
  3. Detection was low due to the small chance of sighting individuals on complex substrate. When derived from repeated sampling, an upper bound on naive detection rate averaged 0.38 and increased with size. When derived from a closed capture–recapture model, average detection was estimated at 0.19.
  4. Growth was highly variable and confounded with detection, but an average 3.4% of detected outplants across all sites (0–7.5% range) had reached reproductive size in 2017.
  5. A state‐space model of exponential population growth was modified to account for imperfect detection and yielded an estimated density of abalone for each survey. Seven out of eight sites included in the model remained above a target abalone density of 0.3 m−2 throughout the project.
  6. The majority of tagged abalone made little net movement over weekly and annual timescales, although some emigration likely reduced survival estimates.
  7. The restoration programme is transitioning from a pilot phase to a production phase, including optimization of hatchery and outplant processes. Existing well‐performing sites will receive additional cohorts every 4–5 years to maintain aggregation densities. New sites will replace poorly performing ones, although this is hampered by a poor understanding of the mechanisms behind site performance.


Carson HS, Morin DJ, Bouma JV, Ulrich M, Sizemore R. The survival of hatchery‐origin pinto abalone Haliotis kamtschatkana released into Washington waters. Aquatic Conserv: Mar Freshw Ecosyst. 2019;1–18.

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About the Author: 
Henry S. Carson, Michael Ulrich, and Robert Sizemore: Washington Department of Fish and Wildlife, Fish Management Division, Olympia, Washington, USA; Dana J. Morin: Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA; Joshua V. Bouma: Puget Sound Restoration Fund, Bainbridge Island, Washington, USA