Walleye Sander vitreus and smallmouth bass Micropterus dolomieu interactions: an historic stable-isotope analysis approach.

The carbon (δ(13) C) and nitrogen (δ(15) N) values of Sander vitreus scales differed pre and post-introduction in treatment lakes among years following the introduction of Micropterus dolomieu. No difference of δ(13) C and δ(15) N in S. vitreus scales was found in control lakes where M. dolomieu were not introduced. In treatment lakes, S. vitreus δ(15) N increased and δ(13) C decreased. No relationship was found between S. vitreus and M. dolomieu abundance in the two treatment lakes. Size structure of S. vitreus and M. dolomieu was negatively correlated and condition of the two species was positively correlated. Although S. vitreus feeding habits may have changed in the treatment lakes after M. dolomieu introductions, evidence suggests that fitness-related factors (i.e. abundance and condition) of S. vitreus remained unchanged, indicating S. vitreus and M. dolomieu may coexist where M. dolomieu have been introduced.