Development of a new ‘ultrametric’ method for assessing spawning progression in female teleost serial spawners

摘要

Examples of assumingly atypical oocyte frequency distribution (OSFD) of spawning individuals. ( ) OSFDs demonstrating the subjective nature of hiatus placement. Placement of the gap limits should theoretically be placed at the upper and lower edge of the PVO and VO cohort, respectively. However, the limits could subjectively be placed at multiple positions within the region indicated by the horizontal dashed line. Furthermore, panel D exemplifies an OSFD where the VO cohort has an unusually long ‘tail’. The upper and lower thresholds used for calculation of oocyte ratio (OR) are shown by the solid vertical lines, the vertical dashed line is the approximate point at which oocytes enter final oocyte maturation (FOM) . All fish in this figure have an oocyte ratio category (ORC) of 1 for standardisation purposes. Oocytes <250 µm are PVOs, 250 to 1200 µm are developing oocytes (VO and FOM), and >1200 µm hydrated or ovulated oocytes. Panel C exemplifies an individual with ‘swelling’ oocytes which are at the end of FOM (see mode at ≈1200 µm).