The pitfalls of diachronic comparisons: fish consumption in the medieval and postmedieval town of Aalst, Belgium

The inland town of Aalst is located on the banks of the River Dender, which is part of the Scheldt basin that drains the major part of Flanders, the northern part of Belgium. In an attempt to look for diachronic trends in fish consumption, ichthyological remains from 34 stratigraphic units, derived from seven different sites within the town, are compared, spanning the period from the twelfth to the end of the eighteenth century AD. It was hypothesised that for the medieval and postmedieval periods, the relative frequencies of the various taxa would reflect the historically established development of marine fish consumption and the gradual decline of freshwater fish exploitation due to overfishing and pollution of local freshwater habitats. While it was taken into account that factors such as social position and purchasing power will have influenced the spectrum of fish consumed, the results show that there is an unexpected large inter- and even intra-site variation, even within a restricted time period, patterns difficult to explain and hampering most interpretations. Considering diachronic comparison of the fish assemblages, this inevitably raises the question whether new insights will be easier to gain from wider generalisation or from going into greater interpretational detail.