Reproduction of the commercial scallop, Pecten fumatus, Reeve, 1852 in Bass Strait, Australia

To examine the reproduction of Pecten fumatus Reeve, 1852, samples were taken monthly from beds off King Island and in Banks Strait, from July 1986 to July 1987. For each sample the mean gonad-free tissue weight and standardized gonad weight were calculated. The percentage of the sample with each of five macroscopically determined reproductive stages was also measured. Changes in the proportion of cell types within the ovarian part of the gonad were determined by histological and stereological methods. A seasonal cycle of gonadal development occurred at each site, commencing at the time of lowest water temperatures and highest nutrient concentrations. This development progressively increased as the nutrient concentrations declined. No correlation was seen between chlorophyll a and gonad condition. A synchrony in gonad condition was present among individuals in samples; this was greatest at Banks Strait where gonads were larger, and phosphate, nitrate and silicate concentrations were significantly greater. There was no reduction in somatic tissue weight with increase in gonad tissue weight. Maximum gonad development preceded spatfall at each site by about one month.