Effect of Overwinter Mortality on Reproductive Life History Characteristics of Pumpkinseed (Lepomis gibbosus) Populations

Pumpkinseed (Lepomis gibbosus) inhabiting two shallow ponds that experienced major winterkills matured 1–2 yr earlier and at a smaller size (difference > 20 mm in length) than conspecifics living in an adjacent, nonwinterkill lake. Pond females were more fecund relative to body weight, and their gonadosomatic index was about double that of lake females. Pond males showed a significant, but less drastic increase in gonadosomatic index over lake males. Winterkills occurred in different years in the two ponds, but in both cases, pumpkinseeds showed significantly lower age and size at maturity following winterkill in comparison with a preceding or subsequent nonwinterkill year. These results are consistent with life history predictions for organisms living in fluctuating environments and indicate that reproductive life history traits are very plastic in pumpkinseeds living in high-risk environments. Advanced maturity following winterkill may be the result of abundant food supply to survivors or release from social factors that prevent maturation of small pumpkinseeds.