The distribution of genetic variation for NAD+ malic enzyme ( ME* ) polymorphism in the Atlantic salmon was assessed in both anadromous and resident populations. The analysis revealed a major allelic divergence between North America and Europe. The *80 variant occurred in 39 of 40 North American samples, ranging in frequency from 0 to 0.515. In contrast, it was detected in only three fish from two of the 35 European locations...