Intra‐ and Intersystem Variation in Largemouth Bass Recruitment: Reproduction, Prey Availability, and the Timing of Year‐Class Establishment

Abstract

AbstractIncorporating potentially important events during the first year of life across multiple environmental conditions is needed to generalize models of fish recruitment. Using previous conceptual models as a framework, we quantified sources of intra‐ and intersystem variation in recruitment of largemouth bass Micropterus salmoides. We measured age‐0 abundances, first‐year growth, and potentially important environmental variables across 12 populations and 5–7 year‐classes. Interpopulation differences in average recruitment to age 1 were set by variation in number of age‐0 fish surviving to the fall. Survival to fall was in turn positively related to density of juvenile bluegills Lepomis macrochirus. First‐year growth was positively related to turbidity and adult largemouth bass abundance. For individual lakes, variables explaining a significant amount of intrapopulation variation in recruitment strength were factors associated with either production of age‐0 fish from the parental care stage (peak density of age‐0 largemouth bass) or prey fish abundance (densities of larval and juvenile bluegills). Abundance of larval bluegills was higher in systems where largemouth bass recruitment to age 1 was not related to bluegill abundance than in lakes where recruitment strength was sensitive to annual fluctuations in prey fish abundance. The relationship between output from the parental care stage and recruitment strength suggests that largemouth bass management should focus on actions designed to influence nest success. Where recruitment is also limited by prey fish availability, management actions can also be directed towards community attributes that influence the growth and production of important prey species.