The southern blue whiting (Micromesistius australis) is an important resource in New Zealand, Chile, Argentina, the Falkland Islands and international waters (Niklitschek et al. 2010). Two different subspecies were postulated, one in New Zealand waters (M. australis pallidus) and one in the southernmost area of South America (M. australis australis) (Takeshima et al. 2011). However, this differentiation has not been further studied.

The structure of the Southern American population has been analyzed, and significant differences have been found regarding otoliths, trace metals, stable isotopes, parasite assemblages composition, and genetic structure between the Southeast Pacific Ocean (Chile) and the Southwest Atlantic Ocean (Argentina and Falkland Islands) samples (Arkhipkin et al. 2009)(Niklitschek et al. 2010)(Leguá et al. 2013)(McKeown et al. 2017). Both populations might overlap in the southern feeding areas (Céspedes et al. 1998), but have an affinity to their spawning grounds (Arkhipkin et al. 2009). It was also observed that genetic variation among the Atlantic samples was considerably lower, although these samples were taken shortly before the stock collapsed in 2004-2007, which could indicate genetic erosion (McKeown et al. 2017). However, some uncertainty remains due the otolith similarities and mitocondrial DNA analysis that could indicate some degree of connectivity (Arkhipkin et al. 2009)(Ramos and Winter 2023). The present profile focuses on the SW Atlantic biological stock with both, Argentina and the Falkland Islands, performing stock assessments. The SE Pacific stock is covered in another profile.

Stock assessments are conducted both by Argentina and Falkland. Argentina assesses the whole stock (Zavatteri et al. 2023) whereas Falkland assesses only the portion of the stock that falls within their jurisdictional waters (Ramos and Winter 2023).