Exploring the Generality of Recruitment Hypotheses for Largemouth Bass along a Latitudinal Gradient of Florida Lakes

—Latitudinal influences on growing season length and winter severity cause variation in prerecruitment life history across species distributions. We evaluated two recruitment hypotheses for a broadly distributed species, largemouth bass Micropterus salmoides, at the southern extent of their natural range. We tested (1) whether early hatching provided a growth and survival advantage relative to later hatching through their first summer and (2) whether overwinter size-selective mortality strongly influenced recruitment to age 1 across Florida’s latitudinal gradient. We sampled the 2003 and 2004 year-classes at six Florida lakes that spanned latitudes from 2780N to 3085N. Our results did not fully conform to our hypotheses or the results frequently reported from more northerly latitudes because largemouth bass that hatched early did not exhibit a growth and survival advantage at all lakes and we did not detect strong sizeselective overwinter mortality. Early hatching at south Florida lakes resulted in slow growth for three of four lake and year combinations and early-hatched fish never exhibited a survival advantage relative to laterhatched fish, which was probably due to cool water temperatures soon after hatching. Environmental variability influenced the interactions between hatching period, growth, and survival for Florida’s largemouth bass populations, which has implications for understanding fish recruitment across broad spatial scales. Aquatic ecologists and fisheries managers struggle to understand fish recruitment because it is highly variable and both density-dependent and densityindependent factors influence prerecruitment survival (Post et al. 1998). Environmental (e.g., temperature) and biological (e.g., energetics and predator–prey relationships) factors interact to influence recruitment processes (e.g., hatching dates, growth, and mortality), but the relative strengths of those recruitment processes can vary greatly with latitude (Conover 1992; Garvey et al. 2002b). Establishing latitudinal patterns in hatching, growth, and survival of juvenile fish is a goal of ecologists (Garvey et al. 2002b) and facilitates understanding of species-specific variation in life history traits across large spatial gradients (Conover