This paper examines interactions between co-occupants of riverine niches in north-west Europe during the Late Upper Palaeolithic using both ecological and archaeological data. It is argued that consideration of both the Lateglacial record and autecology of eel, beaver and horse supports a reinterpretation of some famous but enigmatic panels of Magdalenian mobiliary art as representations of eel fishing, along with horse and beaver exploitation in disturbed riverine habitats. It is further suggested that this constitutes a humanly co-constructed niche in ecological, nutritional, and symbolic terms, which was also particularly advantageous for human well-being and social development in this time and place.