Estimating Abalone Growth and Shell Morphometrics on a Sea Ranch in South-Western Australia

This study estimated the growth of tagged, hatchery-reared Haliotis laevigata (Greenlip abalone) released (“seeded”) on artificial habitats (Abitats) in Flinders Bay, south-western Australia. It also evaluated a mark in the shell detected after transferring abalone from the hatchery to the ocean as a predictor of the size-at-release for the abalone. The research was carried out as part of commercial operations on the sea ranch which limited some of the data collected. A total of 117 tagged H. laevigata were released on the Abitats and harvested across three areas (lines). Growth in shell length (SL) was significantly slower on one line (1.96 mm month-1) than the others (2.33 mm month-1 and 2.44 mm month-1), possibly due to different pre-seeding histories. Slower growing abalone were retained in the hatchery for an additional 74 days compared to the faster growing abalone. However, growth in wet weight did not differ significantly among lines (2.22 g month-1). This study provides the first estimates of the different shell-length characteristics for juvenile abalone: the mean (± 1 SE) SL: shell width ratio was 1.31 ± 0.005 and the SL: shell depth ratio was 4.94 ± 0.057, much greater than these ratios for mature H. rubra in southern Australia. The hatchery mark at harvest was a significant linear predictor of the shell length at seeding and was still present in abalone at harvest size (~100 mm SL), providing a way of estimating growth in H. laevigata on the sea ranch without the need for tagging.