Seasonal Reproductive Patterns of Pumpkinseed (Lepomis gibbosus) Populations with Varying Body Size Characteristics

Abstract

To assess the implications of reproduction on body size and the potential physiological constraint imposed by small body size on reproductive patterns, we examined seasonal nesting patterns and gonad allocation in six pumpkinseed (Lepomis gibbosus) populations exhibiting a range of adult body size characteristics, We found that the two populations exhibiting stunted adult body size initiated nesting activity 1-wk later and had nesting periods 3–7 wk longer than the other four populations. Mean adult body size showed a significant negative correlation with both length of spawning season and gonadosomatic index in the six populations. Within populations, smaller females matured later in the season than larger females. Our results suggest that small adult body size is associated with high reproductive effort and that variation in the timing of reproduction is a consequence of differences in energy reserves between small and large individuals. The extended spawning season of some populations may result in a higher cost of reproduction than that which would be predicted from gonad size alone. Small individuals forced by energy limitations to spawn late in the season are likely to produce offspring with lower survival rates, and their reproductive fitness should be discounted accordingly.