Post-larval recruitment of blacklip abalone ( Haliotis rubra ) on artificial collectors in southern Tasmania

Recruitment rates of blacklip abalone (Haliotis rubra) post-larvae were measured at fortnightly intervals for a year in southern Tasmania on larval collectors made of transparent, corrugated plastic. The settlement plates were conditioned prior to use in a flow-through sea-water system in a two-stage process. A film of diatoms (mainly Nitzschia and Navicula species) was first established on the plates, which were then grazed by juvenile H. rubra. This allowed second-phase algae (principally Myrionema species) to become established. The plates were then periodically deployed at a depth of ~7 m. Larval settlement occurred mainly during the austral winter and early spring. A peak settlement rate of 1408 post-larvae per collector (2347 post-larvae m-2) occurred in mid August. Methods of measuring larval or immediate post-larval abundance are reviewed with regard to their use in the assessment and management of abalone fisheries.