Spatial Synchrony of Yellow Perch Recruitment in Eastern South Dakota Glacial Lakes

We evaluated the extent of spatial synchrony in recruitment and estimated factors related to year-class strength in yellow perch populations among 37 eastern South Dakota glacial lakes sampled with gill nets in 2009, 2010, and 2011.  Distance between lakes ranged from 1.7 km to 134.5 km.  The extent of spatial synchrony among lakes was assessed using cross-correlation analysis of cohort catch per effort data.  Correlation coefficients for the 136 bivariate correlations included in correlative analyses ranged from -0.47 to 0.99 (mean = 0.71), with 79% of correlations greater than 0.50, 64% of correlations greater than 0.70, and 37% of correlations greater than 0.90, suggesting synchronous population fluctuations.  The extent of synchrony was not related to distance between lakes, at least not within the spatial scale included in this study.  Year-class strength was assessed relative to combinations of climatic and hydrological variables using an information-theoretic approach.  The winter severity and hydrological models received the most support, suggesting that year-class strength and synchronous population fluctuations over a broad spatial scale are influenced by the severity of the first overwinter period and by hydrological conditions during early ontogeny.