An assessment of breeding in the intertidal limpet, Cellana radians (Gmelin)

The breeding cycle of Cellana radians (Gmelin), an intertidal patellid limpet endemic to New Zealand, was investigated over 12 months. Two techniques were used: a subjective index obtained by the visual assessment of the relative size of the gonads, and a quantitative index obtained from regressions of wet gonad wt on wet body wt. Breeding activity occurred during most of the year and there was only a very brief resting stage. Three spawning events were identified, and a fourth was likely. Frequent use of the descriptive method during part of the cycle permitted the identification of the precise spawning times for two of these events. At these times, spawning was apparently synchronous for all members of the population, and a large proportion of the gonad was spawned out. Accurate estimates of gonad output and fecundity were obtained for these spawnings by comparing the weights of gonads and numbers of eggs present before and after spawning. The results and efficiencies of the two methods of gonad assessment were compared. Each method gave the same pattern of events. The combination of the two methods provided a very efficient system for the detailed analysis of breeding in C. radians. We suggest that this procedure may be more appropriate for examining the reproductive cycles and fecundities of limpets with long breeding seasons and synchronous spawning of individuals than those which have been previously used.