Samples of Merluccius hubbsi (N=147) were collected from the southwest Atlantic, in the high seas at 42o S and 46oS and from the waters around the Falkland Islands. A sample of M. australis (N=23) was also collected in Falkland Islands waters. Variation in the population structure was investigated using multivariate analysis of a total of external and skeletal morphometric data, counts of fin rays and teeth, and measurements on scales. All measurements were standardised to mean body size and each character set was analysed separately. Principle components analysis and discriminant analysis were used to identify differences between M. hubbsi from different areas and differences between the two species. The results indicate the presence of two groups of Merluccius hubbsi within the study area, one found on the high seas and one in the waters around the Falkland Islands. Results are discussed in relation to the reproductive and trophic migrations of M. hubbsi, the relative importance of genetic and environmental differences, and the results of similar studies from the southwest Atlantic
