. The Canadian field-naturalist. 238 The Canadian Field-Naturalist Vol. 106 Table 1. Summary of fecundity (mature eggs) data for redbelly dace, (r represents regression of fecundity on length) DACE EGGS Date «65 mm > 65 mm total mean range r- P 1984 21 June 9 3 12 331 91 182-500 < 28 June 18 13 31 246 71 125^30 8 July 7 5 12 157 146 12^38 < 23 July 6 15 21 194 78 72-342 mm) or pockets of transparent eggs. Immature ovaries were those which contained no eggs with yellow yolk. We determined that small fish would be consid- ered 65 mm based on an
. The Canadian field-naturalist. 238 The Canadian Field-Naturalist Vol. 106 Table 1. Summary of fecundity (mature eggs) data for redbelly dace, (r represents regression of fecundity on length) DACE EGGS Date «65 mm > 65 mm total mean range r- P 1984 21 June 9 3 12 331 91 182-500 < 28 June 18 13 31 246 71 125^30 8 July 7 5 12 157 146 12^38 < 23 July 6 15 21 194 78 72-342 mm) or pockets of transparent eggs. Immature ovaries were those which contained no eggs with yellow yolk. We determined that small fish would be consid- ered 65 mm based on an apparent natural separation of lengths among collect- ed dace. GSI measures are presented from 1984 and egg size distribution from 1985. Simple linear regression was utilized for the fecundity analysis on the data collected in 1985. Results In both years, the spawning season extended from June through July with most fish still maturing in May, and spent by the middle of August. Plots of the GSI by size groups in 1984 displayed a gradual rise through 28 June, with peak ovary weight occurring in late June and early July (Figure 1). Values then declined, confirming that fish were spent by mid- August. Seasonal patterns of the GSI were similar for both size classes of dace. Regressions of fecundity on total length revealed no consistent relationship between numbers of eggs and size of dace (Table 1). Diameters of maturing and mature eggs followed a bimodal distribution in May and June for both small and large dace (Figure 2). A lower proportion of mature eggs (> mm) was observed as July progressed. 21 28 June Figure 1. Gonado-somatic indices (GSI) for Northern Redbelly Dace in 1984. Error bars are one standard Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists
Size: 2030px × 1231px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorottawafi, bookcentury1900, bookdecade1910, bookyear1919
