Otoliths, a calcified structure in the inner ear of fish, are occasionally recovered during archaeological excavations . They are unique among zoo-archaeological material in that they simultaneously convey information on individual fish age , growth  and reflect the environmental conditions that the fish encountered throughout life-history [12–14]. Otoliths from archaeological excavations have been used to examine historical changes in fish age [15, 16], trophic position  and seasonality of human site occupation . Importantly, otoliths allow measures of annual growth, and thereby retrospective reconstructions of fish growth patterns. Growth reconstructions from archaeological otoliths have for example shown higher growth rate of Neolithic Baltic cod than in the modern population, particularly in the first year of growth . Conversely, research from the North Sea finds slightly slower growth rate of cod (as well as haddock and plaice) in early modern times than in recent times .