Translocation of endangered black abalone (Haliotis cracherodii) as a population restoration tool

Abstract

Introduction: Conservation translocations are an essential tool for species restoration but come with inherent risks that require careful consideration. However, accelerating ecological change lends urgency to minimizing delays in restoring populations, biodiversity, and ecosystem function. The endangered black abalone (Haliotis cracherodii) is a large marine gastropod in eastern Pacific rocky intertidal ecosystems ranging from California, USA to Mexico that was decimated by disease in the 1980s-1990s. Natural recovery has been hindered by density-dependent reproduction. This study presents the first planned conservation translocation of black abalone, facilitated by a broad-scale, decades-long, monitoring program (Multi-Agency Rocky Intertidal Network, MARINe). Existing MARINe partnerships facilitated collaboration among agency, academic, non-profit, and for-profit partners to move the translocation effort forward quickly and efficiently.

Methods: In 2023, 246 abalone were translocated in two phases from a recovering population on The Nature Conservancy (TNC) preserve on Santa Cruz Island to TNC’s protected Jack and Laura Dangermond Preserve into areas where critical habitat was restored. Lessons learned in Phase 1 were applied to Phase 2 including refined collection protocols and injury prevention/assessment.

Results: Survivorship during the translocations (from collection to field release) was very high, with a mortality rate of just 1.6%. Monitoring of abalone indicated a retention rate of more than 80% three years post-translocation, assuming no crypsis (translocated survivors not found during monitoring). However, post-release retention was likely closer to 100% when adjusted using the most conservative crypsis rates from prior abalone translocations. Post-translocation movement of abalone was higher than expected, but a high level of fidelity was associated with areas where habitat had been restored. The presence of juvenile black abalone provides encouraging evidence of recent recruitment at the restoration site, although genetic parentage analyses are needed to determine origin of juveniles.

Discussion: Three years in, our results demonstrate early signs of success through high retention of translocated abalone and increased local population density to a level capable of supporting larval production. This effort underscores the importance of protected areas as living laboratories and demonstrates how cross-sector collaborations can safely accelerate the pace and scale of endangered species recovery.

Citation

Fletcher NC, Miner CM, Heady WN and Raimondi PT (2026) Translocation of endangered black abalone (Haliotis cracherodii) as a population restoration tool. Front. Conserv. Sci. 7:1952618. doi: 10.3389/fcosc.2026.1952618