BATCH-TAGGING BLACKLIP ABALONE (HALIOTIS RUBRA) FOR IDENTIFICATION OF HATCHERY-REARED INDIVIDUALS ON NATURAL COASTAL REEFS IN NEW SOUTH WALES, AUSTRALIA

The identification of hatchery-reared larvae and juveniles is fundamental to assessing the success of their release when restocking. Hatchery-reared Haliotis rubra larvae and juveniles were successfully batch-tagged with distinct and persistent marks, enabling unambiguous differentiation from wild conspecifics when recaptured. Larvae were batch-tagged with the epifluorescent dye calcein. Experiments demonstrated that the batch-tagged larval shell was clearly visible in the spire of juvenile shells after 260 days. The recapture of batch-tagged and released larvae from natural reefs after 533 days at liberty also confirmed the persistence of this tag. A reliable and cost-effective method for batch-tagging juveniles was achieved with the use of an artificial diet that resulted in a distinctive blue-green coloration of the shell. This coloration differentiated released juveniles from wild conspecifies, was easily observed with the naked eye, and persisted on the spire of individuals for 777 days at liberty. These batch-tagging protocols allow large numbers of H. rubra larvae and juveniles to be distinctly tagged for long periods of time, enabling reliable estimation of survival after release and individual growth. It is likely that these techniques could also be applied to other abalone species.