Long-term occurrence of Atlantic bluefin tuna Thunnus thynnus in the North Sea: contributions of non-fishery data to population studies

•Information on tuna distribution, fishery, consumer acceptance in the Northern Europe.•Continuous high abundance of tuna in the North Sea before 1900 is not probable.•Observations of tunas from March till November.•Large schools of tuna in the Meuse-Scheldt area in the 1910’s and 1920’s.•Natural history books and newspaper databases proved to be valuable sources.