Relative abundance (RA, mean ± SD, %) and occurrence frequency (OF, %) of zooplankton found in little auk gular pouches in 2012 and 2014, and in at-sea samples collected in 2014; and linear food selection index (mean ± SD, %) for 2014 prey.

Calanus hyperboreus, C. glacialis and C. finmarchicus groups included the stages CIV, CV, and adult males and females. Other copepodite stages of these 3 species were included in the ‘Calanus CI-CIII’ group. Species included in the ‘small copepods’ group are Triconia borealis, Scaphocalanus magnus, Metridia longa and Microcalanus spp for the Continental shelf, and Triconia borealis, Metridia longa and Microcalanus spp for the shelf break and the open ocean. Main little auk prey species are in bold. Asterisk indicates ice-associated prey. Continental shelf, shelf break and open ocean groups were defined based on isobaths ( 1500 m respectively). Linear food selection index is the difference between prey proportion found in little auk gular pouch and prey proportion in the environment and ranges from -1 to 1 [38]. A positive value indicates preference and negative or null values avoidance or unavailability.