Size- and age-related variation in the seasonal timing of nesting activity, nest characteristics, and female choice of parental male pumpkinseed sunfish (Lepomis gibbosus)

Abstract

Parental males from a population of pumpkinseed sunfish (Lepomis gibbosus) were captured throughout the spawning season to examine age- and size-related seasonal trends in nesting activity. Females of spawning pairs were also captured to determine if male body size or nest characteristics influenced their selection of a mate. Large/old (≥ 80 mm; age 4–6 years) parental males commenced nesting earlier in the spring–summer spawning season than small/young (< 80 mm; age 2 and 3 years) parental males. As the spawning season progressed, the proportion of large/old males in the nesting population decreased until more than 70% of the males nesting late in the season were small/young individuals. Small individuals nesting late in the season were inferior in body condition to those that nested earlier in the season. These findings support the hypothesis that size-related differences in energy reserves and metabolism in centrarchids result in size-dependent variation in the timing of nesting activity. The length of females captured spawning at a nest site was not significantly correlated with the length of the parental male, water depth, or distance from shore; however, females captured spawning in firm (sand and gravel) substrates were significantly larger than those spawning in soft (silt or woody debris) substrates. Although all observed nests in the various substrates contained eggs, the positive relationship between body size and fecundity in female pumpkinseeds suggests that a selective advantage for males nesting in firm substrate may accrue through the attraction of larger females.