Relationships among Fat Content, Condition Factor, and First-Year Survival of Florida Largemouth Bass

Abstract

Major reductions in abundance of age-0 largemouth bass Micropterus salmoides (76–87%) occurred between May and June (1981) or between June and July (1980, 1982) in Lake Dora, Florida. The severity of this mortality was not consistently related to spawning success, as measured by densities of age-0 fish in spring block-net samples before the periods of heavy mortality. High-mortality periods typically coincided with diet shifts towards piscivory. Age-0 largemouth bass exhibited the least piscivory at the same time that biomass ratios of available fish prey to predators were lowest in the two years (1980, 1981) they were measured. The lowest observed prey: Predator ratios also preceded periods of major mortality. This period of density reduction was accompanied by a significant reduction in percentage fat of age-0 fish in 1980 and 1982, but not in 1981. The major reductions in density of age-0 largemouth bass between May and July were believed to represent a survival bottleneck that should be considered in conjunction with stock assessment and management efforts directed at this species.