Otolith death assemblages provide a valuable source of biological and ecological information that can help address three main problems in marine conservation: (a) the lack of pre-industrial, pre-human-impact baselines for evaluating change; (b) the inefficiency of survey methods for recording small and cryptic fish species; and (c) the absence of long-term data on environmental change impacts on marine ecosystems and fishes. We review here the current knowledge on the formation and preservation of otoliths and their death assemblages, and the methods to obtain, date and analyse them in order to detect changes in the species traits and ecology, the fish population structure and the palaeoceanographic shifts that drove them.