Reviews in Fish Biology and Fisheries, 4, 300-325 (1994) Appraisal of molecular genetic techniques in fisheries ROBERT D. WARD* and PETER M. GREWE CSIRO Division of Fisheries, GPO Box 1538, Hobart, Tasmania 7000, Australia Contents Introduction and historical overview Summary of molecular techniques for revealing genetic variation Uses in stock structure analysis Uses in aquaculture Monitoring levels of genetic variation Monitoring introduced or transplanted stocks Other aquaculture uses Uses in species discrimination Species identifications. Hybridization Some other issues Conclusions Summary Acknowledgements References page 300 301 303 310 312 314 315 316 317 317 Introduction and historical overview Molecular genetic approaches began to be used in fisheries in the 1950s. These initial studies were of blood group variants, primarily in tunas, salmonids and cod (reviewed by de Ligny, 1969), and successfully demonstrated the existence of genetically controlled variation which could be used in analyses of population structure. However these sero- logical procedures were not enthusiastically adopted by fisheries biologists and most were subsequently abandoned in favour of electrophoretic procedures revealing genetically determined protein polymorphism. One of the first of these studies was that of Sick (1961), who described haemoglobin variants in whiting (Gadus melangus, Gadidae) and cod (Gadus morhua, Gadidae), but the impetus for more extensive work was provided by the seminal papers of Harris (1966) and Lewontin and Hubby (1966). They showed humans and the fruitfly Drosophila pseudoobscura, respectively, to be highly polymor- phic for electrophoretically detectable allozyme variation. Protein electrophoresis was found to be quick, reasonably inexpensive, and reproducible. Most plant and animal *Author to whom correspondence should be addressed. 0960-3166 © 1994 Chapman & Hall