Brill (Scophthalmus rhombus) is a shallow-water flatfish mainly found in areas close inshore. It prefers sandy bottoms, but can sometimes also be found on gravel and muddy grounds. Its vertical distribution ranges from 4 meters to 73 meters. The distribution of brill in the North Eastern Atlantic ranges along the European coastline from 64° N (the Lofotes) down to 30° N, extending into the Mediterranean and even into the Black Sea (Nielsen 1986). Brill is also found in the Skagerrak, the Kattegat, and small quantities in the Baltic Sea. The western limit of its distribution area is reached in southern Iceland. The distribution in the North Sea, Skagerrak and Kattegat, based on presence/absence in a number of surveys (ICES 2010).

Brill is distributed mainly in the western part of the Baltic Sea and Brill fishery is dominated by Denmark in SD 22 (95% of the catches in 1985–2009, ICES 2010).

No genetic differentiation could be found between Atlantic and Mediterranean populations, suggesting that there are also very low levels of differentiation in brill from different areas (Blanquer et al. 1992). Stock structure of brill in the Baltic Sea is still unclear but an assessment unit is considered within ICES Subdivisions 22-32 (ICES 2015a).