Microstructure, chronology and growth of the pinto abalone, Haliotis kamtschatkana, in Alaska

The microstructure, deposition of rings, and growth checks in the pinto aba lone, Haliotis kamtschatkana Jonas, were examined at seven sites in southea st Alaska. Rings were of calcium carbonate with prismatic or block-like str ucture or were of organic material (called brown rings); sometimes both typ es were juxtaposed in a compound ring. Rings alternated with nacreous layer s having a brick-like or laminar structure. Laminar thickness was correlate d with ambient sea temperatures and provided internal evidence of periodici ty of ring deposition. One ring a year appears to be deposited in the spire of this abalone in about mid-sumner, and a growth check is laid down at th e growing edge of the shell in about mid-winter. Rates of deposition of the rings and growth checks were validated by comparison with known growth rat es from mark-recapture experiments at one site, and modal analysis of lengt h frequency data at others. Examination of a sample of shells of known age confirmed a deposition rate of one ring a year. Brown rings appear to be la id down adventitiously and were excluded from ring counts for aging purpose s. The three independent techniques, rings, growth checks. and modal analys is, gave consistent juvenile growth rates at 7 sites of 14-18 mm/y during t he first 4 y. Thereafter, growth rates followed a declining exponential cur ve. Growth rates differed little between sites, and mean parameters of fitt ed von Bertalanffy growth parameters for seven sites were: K = 0.20: L-infi nity, = 125.9 mm.