Morphological Discrimination of Yellow Perch Stocks in Lake Erie

     Yellow perch Perca flavescens is a heavily exploited species in Lake Erie supporting thriving commercial and recreational fisheries.  Harvest allocations and population projections are presently made for management units (MU), which are roughly aligned with the natural trophic gradient of Lake Erie, but which may not be aligned with stocks of yellow perch.  We examined whole-body morphometrics, which have been used successfully to distinguish fish stocks in the Great Lakes and elsewhere, to determine if yellow perch stocks correspond to management units.  Yellow perch were captured in research bottom trawls and trap nets and commercial trap nets in known spawning areas during spawning (late April to early June) between 2007 and 2009 for morphometric analysis.  We used Principal Component Analysis (PCA), Discriminant Function Analysis (DFA), and ANOVA of axes from PCA to examine whole-body morphometrics of 2,092 adult male yellow perch among the three major basins of Lake Erie (western, central, and eastern), four MUs, and sites within MUs to determine if morphological differences conformed to MU.  There were significant differences in morphometrics among MUs and among sites within MU, suggesting yellow perch stocks exist at scales finer than MU in Lake Erie.  This work corroborates genetic studies that concluded yellow perch stocks are not aligned with MU.  Differences in glacial refugia of early colonizers of Lake Erie, and barriers to dispersal such as lake currents and deep water, likely resulted in and maintain yellow perch stocks.