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. (2024).This dataset is included in the OA-ICC data compilation maintained in the framework of the IAEA Ocean Acidification International Coordination Centre (see https://oa-icc.ipsl.fr). Original data were downloaded from the PANGAEA dataset (see Source). In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2024) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2026-05-27.