Pattern, synchrony and predictability of spawning of the tropical abalone Haliotis asinina from Heron Reef, Australia

Abstract

The spawning biology of the tropical abalone Haliotis asinina on Heron Reef, Australia, was investigated to identify putative environmental and endogenous factors controlling spawning. Spawnings by H. asinina were highly regular and, in comparison to most other haliotids and marine invertebrates, frequent and extremely synchronous. These events appeared to be regulated by more than 1 environmental cue. The spawning season of H. asinina extends from October to April and is associated with an increase in water temperature. During the spawning season, recently captured abalone, housed in flow-through aquaria, released gametes for 2 nights every 2 wk during the new and full moons. However, the exact date of spawning did not correlate precisely with the lunar cycle. Occasionally the spawning events between 2 populations of H. asinina on Heron Reef that were 1.5 km apart differed by 1 d, suggesting that differential tidal regimes might influence the date of spawning. The population that was exposed to slightly longer spring low tides occasionally spawned 1 d earlier.