Adult lake whitefish (Coregonus clupeaformis) from Clearwater Lake and second generation adults of offspring from Clearwater whitefish transplanted to Lyons Lake were compared with respect to morphometric and meristic characters and isozymes of L-glycerol-3-phosphate dehydrogenase (GPDH). Feeding habits and abundance of pelagic and benthic foods were compared in the two lakes.Gill raker number, lateral line scale count, and interorbital width remained constant between parental and offspring populations. Gill raker length was the main character found to differ between the populations. This was found to be related to the percentage and type of benthic food eaten. Abrasion of the gill rakers is offered as an explanation for the differences in gill raker length. Differences were found in various other meristic and morphological characters, as well as in electrophoretic phenotype frequencies of isozymes of GPDH.