Reproduction on two species of abalone (Haliotis iris and H. australis) in southern New Zealand

Abstract

Gonad development, spawning periodicity, fecundity and recruitment of two species of abalone, Haliotis iris and H. australis, were examined at two sites. Female H. iris spawned in April and September 1986 and March 1987, and decreases in male gonad indices coincided with these events. Oocyte size frequencies showed that the summer-autumn (April 1986, March 1987) spawnings were more pronounced than that in September 1986. Gonad indices of H. australis were low in December 1985 and March 1986, but oocyte size frequencies in September 1986 and March 1987 indicated that other spawnings occurred. Gonad development within and between sites was variable, especially for H. australis. H. iris had a female : male ratio of 1 : 1 at one site and 1.7 : 1 at the other; H. australis was 1 : 1 at both sites. In H. iris, the smallest females with primary and mature oocytes were 56 mm and 69 mm respectively, and the smallest male with sperm was 80 mm. H. australis females had primary and mature oocytes at 61 mm, and the smallest mature male was 65 mm. Fecundity varied between species. At 80-90 mm, H. iris had 13 500 eggs and H. australis had 2.7 million eggs, but at 140 mm H. iris had 7 million eggs. A few recruits of both species were found in May-April 1986, probably the result of the previous September spawnings.