Аннотация:Among Salmo salar and S. trutta parr in the Keret and Nilma rivers, White Sea Basin, hybrids between these species have been identifield, by means of electrophoresis. The loci coding the enzymes esterase-D (ESND*)and mannose-b-phosphateisomerase (MPI*) were used for their diagnostics. It is supposed that the origin of hybrids between these two species in natural and has resulted mainly from anthropogenic influences.