In the Atlantic Ocean blue shark is found from Newfoundland to Argentina and from Norway to South Africa where, based on different scientific studies related to tagging, migration cycles and reproduction areas (e.g. Castro and Mejuto, 1995; Fitzmaurice et al., 2005) three stocks are considered: North Atlantic, South Atlantic and Mediterranean (ICCAT, 2008; FIRMS, 2008; Valeiras and Abad, 2009).

However, within the South Atlantic, the possible existence of two stocks, in the equatorial area and in the southwestern area, is defended by Domingo et al. (2008). 

The latest stock assessment performed by the Standing Committee Research and Statistics (SCRS) in 2015 (ICCAT 2015) performed separate assessments for the North and for the South Atlantic stocks. This report also acknowledges that more research is needed to improve the current knowledge of this species in the Mediterranean.