This paper reviews and discusses the uses of genetic markers in analyz
ing the composition of population mixtures of fishes. Such analyses re
quire (1) the existence of genetic differences identified in base-line
data from contributing populations, and (2) an adequate sampling of i
ndividuals from the mixture to characterize its composition. Genetic a
nalyses of complex population mixtures of salmonids began around 1980
and subsequently have been increasing; applications have included esti
mates of geographic origins in marine and freshwater fisheries, and of
ancestral origins in populations reestablished from multiple sources.
The potential for applications of genetic analyses of population mixt
ures is more limited in most marine species because such species are t
ypically less genetically subdivided than salmonid species. However ge
netic analyses are feasible in any species in areas of intermingling o
f genetically distinguishable populations. In addition, genetic markin
g by preferential breeding of genetically distinguishable individuals
may be used to establish genetically distinct cultured populations wit
hin species amenable to artificial propagation.