Several genetic and tagging experiments have been conducted in the NE Atlantic region (e.g. Hoarau et al., 2002; Was et al., 2010; Ulrich et al. 2013). The stock complex consists of sub-populations with distinct spawning grounds; some of them present a strong fidelity behaviour (Hunter et al., 2003) however gene flow is also found among some populations (Hoarau et al., 2002). Different assessments are performed within ICES division VII: Irish Sea (VIIa), West of Ireland (VIIb,c), Eastern English Channel (VIId) and Western English Channel (VIIe), Celtic Sea (VIIf,g), SW of Ireland (VIIh-k).