Sites of collection of the grey seals studied for the dietary proxies.

ICES areas of the Baltic Sea and number of different grey seal individuals collected from the subdivisions 27, 29 (only the north-eastern part i.e. the archipelago between Åland Islands and Turku, was included), 30 (divided into SD30 west and SD30 east groups) and 32 (eastern part, the Russian sea area decluded), and studied for A) gut contents (HP and DNA, n = 129 and 125, respectively) and B) tissue chemical markers (blubber FAs and tissue SIs, n = 108). Seal individuals (M = male, F = female) were further categorized by the way/place of collection: T = trawl, S = surface fyke, B = bottom fyke, C = close to fishing gear, F = by fish farm, O = open water, UD = undefined fishing gear and UK = unknown hunting area (C/F/O inside the SD). Bycaught seals = T, S, B, UD; hunted seals C, F, O, UK.