Biomass (mg dry mass m-3) of zooplankton taxa was calculated from samples of Polarstern cruise PS78 (ARK-XXVI/1) on a transect across Fram Strait. Individual dry mass was calculated using established length- weight relationships for Arctic mesozooplankton taxa (Table 4 in Cornils et al. 2022). Samples were taken with the Multinet midi (Hydrobios, Kiel), which is equipped with five nets (mesh size: 150 µm). Samples were analysed via image-based ZooScan analyses. The classified images are available at the web application EcoTaxa: https://ecotaxa.obs-vlfr.fr/prj/2771