Asynchronous Bluegill Recruitment in Four South Dakota Impoundments

ABSTRACT

We quantified recruitment patterns and modeled the relation of climatic variation to bluegill (Lepomis macrochirus) year-class strength in four South Dakota impoundments. Because year-class strength of many species in the northern Great Plains can be erratic due to abiotic factors, we hypothesized that recruitment among populations would be synchronous and that broad-scale climatic patterns would likely affect bluegill survival and subsequent recruitment. We used the residual method based on otolith age structure to assess relative year-class strength and examined six candidate models using the Akaike's information-theoretic approach to determine the influence of temperature, precipitation, and winter severity (and combinations of these variables) on bluegill recruitment. We found that bluegill recruitment was asynchronous, and all three single variable models performed similarly (Δi <1) and were more supported than combinations of variables. However, the single variable relationships were weak indicating that biotic influences likely had more influence than climate on bluegill recruitment in these systems.