Ecology of New Zealand abalones, haliotis species (mollusca: Gastropoda): 4. Reproduction

Abstract

The spawning season of Haliotis iris Martyn, as indicated by a gonad index and examination of ovaries, was late summer to autumn at Kaikoura, New Zealand, in 1967–68. In contrast, H. australis Gmelin spawned twice, once in the spring and again in the late summer to autumn. Both patterns are typical of haliotids. But in the 1968–69 year neither species spawned; full gonads with apparently ripe eggs were maintained through the winter of 1969. No reason for this inconsistency can be offered. Haliotis iris at Taylors Mistake, 154 km south, followed essentially the same pattern as Kaikoura H. iris through 1968, but spawned slightly in autumn 1969. Haliotis iris first produces mature eggs when it is about 60 mm long and probably spawns substantially for the first time when it is 4 years old. Although fecundities of larger animals reached about 11 million eggs, not all of these were necessarily spawned. Haliotis australis also first produces mature eggs when it is about 60 mm long, but the age at which first spawning takes place could not be determined; maximum fecundity is about 3 million eggs. The sex ratios did not differ significantly from 1: 1 for either species. © 1973 Taylor & Francis Group, LLC.