Effects of Body Size and Population Density on Overwinter Survival of Age-0 Pumpkinseeds

Abstract

Abstract We examined the effects of body size and population density on overwinter survivorship of age-0 pumpkinseed Lepomis gibbosus in a laboratory experiment. Pumpkinseeds were captured from a pond in central Ontario in mid-November 1992 and divided into two size-classes (20–24 mm and 30–37 mm total length). Fish were stocked at two biomass density levels (0.12–0.13 and 0.27–0.30 g/L) into four 22-L aquaria where they were maintained at 4°C without feeding. Large age-0 individuals survived significantly longer than their smaller cohorts, and there was also a significant density effect on time until death. Once the fish became active enough to monitor their movement, the number of fin and body movements by small individuals was significantly greater than those of the large individuals. Instantaneous rate of lipid loss showed a strong negative relationship with body size, and small individuals had a significantly higher percent lipid content at death than large individuals. The earlier death of the small...