Several studies have been conducted to understand European pilchard stock structure widely distributed in the Northeast and Eastern Central Atlantic, and the Mediterranean and Black Sea (e.g. Spanakis et al., 1989; Tinti et al., 2002; Kasapidis et al., 2004; Atarhouch et al., 2006; Chlaida et al., 2006; Silva et al., 2006; Laurent et al., 2007; Chlaida et al., 2009; Antonakakis et al., 2011). However further research is needed considering uncertainties (Kasapidis et al., 2012; ICES, 2014b). Thus here we consider the following assessment units along the European pilchard distribution:
By the International Council for the Exploration of the Sea (ICES):
- Iberian (ICES Divisions VIIIc and IXa) and 2) and Bay of Biscay, Southern Celtic Seas and English Channel (ICES Divisions VIIIa ,b,d and Subarea VII)

By the General Fisheries Commission for the Mediterranean, (GFCM; FAO) of the 8 stock assessment units assumed (FAO, 2009; Kasapidis et al., 2012; GFCM, 2014) these 2 are already covered in profiles:
- Northern Adriatic Sea (GSA 17) and Northern Alboran Sea (GSA 01)

By the Fishery Committee for the Eastern Central Atlantic (FAO, 2013a,b):
- NW Africa central (zones A+B; 32ºN – 26ºN) and NW Africa southern (zone C; 26ºN – the southern extent of the species distribution).