Tracing 600 years of long-distance Atlantic cod trade in medieval and post-medieval Oslo using stable isotopes and ancient DNA

Abstract

36 Marine resources have been important for the survival and economic development of coastal 37 human communities across northern Europe for centuries. Knowledge of the origin of such 38 historic resources can provide key insights into fishing practices and the spatial extent of trade 39 networks. Here, we combine ancient DNA and stable isotopes (δ13C, δ15N, non-exchangeable 40 δ2H and δ34S) to investigate the geographical origin of archaeological cod remains in Oslo from 41 the eleventh to seventeenth centuries CE. Our findings provide genetic evidence that Atlantic 42 cod was obtained from different sources, including a variety of distant-water populations like 43 northern Norway and possibly Iceland. Evidence for such long-distance cod trade is already 44 observed from the eleventh century, contrasting with archaeological and historical evidence 45 from Britain and other areas of Continental Europe around the North and Baltic Seas, where 46 such trade developed in a later period. Diverse biological origins are further supported by 47 significant differences of a range of isotopes, indicating that multiple populations living in 48 different environments were exploited. This research highlights the utility of combining ancient 49 DNA methods and stable isotope analysis to describe the development of marine fisheries 50 during the medieval and post-medieval period. 51 Key words: cod-trade, historical fisheries, aDNA, stable isotopes, long-distance fish trade. 52 53