Postlarvae density and photoperiod effects on the settlement and metamorphosis of the donkey's ear abalone, Haliotis asinina Linne, 1758

Abstract

The effects of photoperiod and density of postlarvae on settlement and metamorphosis of the native abalone, <i>Haliotis asinina</i> were determined in two separate experiments. Abalone larvae were hatched from spontaneously spawned eggs of tank-held broodstock. Experiments were conducted in static water conditions within a 10 day-period. Post-larvae held under at 24 h light regime showed higher settlement rates (mean: 12 %) than did larvae held at different light-and-dark periods (range: 3-9 %). Larvae kept in the dark had the lowest survival (3 %). Postlarvae stocked at lower stocking densities of 100 and 150 l ^-1 had higher settlement rates (12-12.5 %) than postlarvae stocked between 200 and 600 postlarvae l ^-1 (1-5 %).