Populations of the European sardines in the Northeast Atlantic from the Celtic Seas, the English Channel (subarea 7) and the Bay of Biscay (subarea 8) have been considered a single stock unit from a genetic point of view (ICES 2013) (Shaw et al. 2012). However, there is an ongoing debate about whether the sardines from these subareas are single units or two separate ones.

Based on the evidence of population growth rates, adult (2+) movements, densities of different life stages (eggs, larvae, recruits, and adults), somatic growth, and spawning and juvenile concentrations lead to propose two scenarios for the structure of the Northern sardine: i) the stock includes the Bay of Biscay, Celtic Sea and English Channel, and ii) the stock is split in two areas: a) Bay of Biscay and b) Celtic Sea/English Channel (ICES 2016). The Bay of Biscay is considered a data-rich area, whereas the Celtic Sea/English Channel data is limited mostly to landings and a few years of data from acoustic surveys (ICES 2017). Therefore, ICES suggested that providing advice for both subareas separately would have low risks (ICES 2017)(ICES 2021). However, some uncertainty remains in the structure of the stock, as different methodologies and even samples from different years produced diverse outcomes, which points to certain connectivity among populations at a wider regional scale (Neves et al. 2021).  This profile encompasses data and information for the Celtic Sea and the English Channel.