Combining a novel outplant module with metareplication to further abalone restoration capacity in California

ABSTRACTSpecies reintroductions require large resource investments for rearing and placement and are further complicated by the paucity of robust monitoring regimes. Nonetheless, continued population declines in many species necessitate such actions. The white abalone (Haliotis sorenseni) in California has experienced steep population declines and a reintroduction programme through outplanting juvenile, captive-bred abalone is considered necessary for its recovery. A novel module known as the Short-term Abalone Fixed Enclosure (SAFE) was developed to allow red abalone (H. rufescens), a surrogate species that is not endangered and co-occurs with white abalone, a period of adjustment before dispersing. Outplant events were conducted at multiple sites in California, USA and monitored regularly for shells and live animals in a process known as metareplication, considered essential for robust outplant reporting. Time-lapse cameras were also placed on SAFEs to document predator visitation. Live animals and shells both increased on-site throughout the first six months and declined thereafter, with most animals unaccounted for. Empty shells on site were considered a proxy for the mortality rate and the lack of encounters after a short period suggests successful emigration from modules into the reef habitat. Predator visitation was generally low, and no significant differences were found across outplant periods. Results from this study indicate outplant mortality may peak early and predator activity is generally low and unrelated to abalone introduction. This vital step illustrates this outplant method may be an effective tool in restoring abalone to subtidal rocky reefs.KEYWORDS: Abaloneoutplantrestorationmodulemetareplicationtemperate reefmonitoringpredation AcknowledgementsThe authors wish to thank the many divers that participated in abalone outplanting and site selection, as well as the crew of The Marissa, The Garibaldi and The Magician for safe transport and the Cultured Abalone Farm for supplying animals. Private stocking permit issued by the California Department of Fish and Wildlife pursuant to Fish and Game Code section 640.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingWork completed under contract AB133F17CN0158 and grant NA18NMF4540340 for the National Marine Fisheries Service.