Fish during the mesocosm experiment in Raunefjord near Bergen (Norway) in spring/summer 2022. Larvae of several coastal fish species were enclosed naturally (day 0) and supplemented with 95 herring larvae reared in the laboratory (day 6). Following the OAE treatment (day 6), deceased fish larvae were monitored via the sediment trap in 2-day intervals to approximate mortality. At the end of the experiment (day 54), all live fish were caught to assess abundance, biomass and taxonomic composition. Methodological details in Goldenberg et al. (under review).