Restoration aquaculture of the pinto abalone (Haliotis kamtschatkana kamtschatkana Jonas): impacts of rearing method on behaviour, growth and survivorship in the hatchery

Abstract

Pinto abalone (Haliotis kamtschatkana kamtschatkana) populations in Washington State (USA) and British Columbia (Canada) continue to decline despite fisheries closures. For successful recovery, supplementation may be necessary. To determine appropriate culture methods, juveniles were reared in habitat-enriched tanks (supplemented with rocks, macroalgae and sea urchins) or conventional aquaculture tanks and assessed for growth and survivorship in the laboratory over 15 months. No differences in survivorship or growth were observed. Subsequent experiments examined whether abalone behaviour (habitat selection and movement patterns) differed between rearing treatments. Abalone were exposed to one of three predator treatments (sea star arm, small crab, or no predator (control)) and filmed for 8 h. Abalone from habitat-enriched tanks changed habitats significantly more often than abalone from conventional tanks regardless of predator treatment. Significant differences in the percentage of time that abalone occupied the various habitats were also observed. Abalone in the sea star and control treatments primarily occupied the rocks, whereas abalone in the crab treatment behaved differently depending on the rearing method; conventionally reared abalone spent more time in corners, whereas abalone from habitat-enriched tanks spent more time exposed. These results demonstrate that rearing conditions can affect abalone behaviour and should be considered for abalone restoration efforts worldwide.