Malacological Society of Australasia

Molluscan Research

Volume 18, Issue 2 (Australasian Abalone): 31 October 1997. Edited by S.A. Shepherd, P.E.McShane and F.E.Wells

Studies on southern Australian abalone (genus Haliotis) XVII. A chronology of H. laevigata.

S.A. Shepherd and L. Triantafillos.

South Australian Research and Development Institute, PO Box 120, Henley Beach, South Australia 5022.

The abalone Haliotis laevigata deposits 2 rings per year in the spire during the first 4-6 years of life at 11 sites in southern Australia. At two sites it deposits 3 rings per year, and at another, 3 rings per year for the first 3 years and 2 per year in the next 3 years. These rates o ring deposition appear to be dependent on the growth rate; they are not exact for every individual due to individual variation in growth but appear to be a statistical property of the population. The tendency for an integer number of rings to be deposited annually my be related to exogenous cues. Hence at one site where 3 rings per year are laid down they are deposited in about June, September and December each year, corresponding to winter, the spawning season and summer. Long term tag recaptures suggest that these rates of deposition persist in older shells but better validation is required. Erosion of the shell causes the loss of rings, and the attack of muricid and polydorid borers causes the deposition of adventitious rings as well as pigmented rings, called brown rings. These complications need to be considered in estimating the age of a shell from ring counts.

pp. 233-245.