The role that the application of genetic principles can play in the sustainable use and conservation of living aquatic resources is being increasingly appreciated by resource managers, policy makers and the international community. Gene and genotype frequency data can provide information on inter alia

• species identification,
• population stock structure,
• hybridization,
• gene flow,
• inbreeding,
• and the genetic impacts of fishing and aquaculture.

Often, data from other sources, e.g. tag-recapture and morphometrics, cannot provide such information or are extremely difficult to collect in areas such as the Mekong River Basin. Genetic data and other types of data should be used together to understand better the dynamics of aquatic populations both in culture and in the wild.

For species such as Pacific salmon that home to natal streams to reproduce, genetic stock identification is a cost effective means to manage fisheries based on genetic differences among stocks of salmon.

Many other groups of fishes and invertebrates show similar genetic structuring because of geological changes, current patterns, among other things. For many marine species the differences among sub-groups is not large because of spawning behavior, migrations and not as accurate homing to natal areas as salmon. Genetic differences have also been used to give endangered species protection to valueable groups of fishes for example in the USA under the Endangered Species Act. Application of genetic improvement in aquaculture and culture-based fisheries is progressing rapidly and population genetics can also be applied to the study of cultured groups of fish in order to choose appropriate breeds to crossbreed and to monitor inbreeding.