Introduction to the 6th international otolith symposium

Fish otoliths have been used as natural recorders of age and growth information in fishes for over a century after the identification of otolith age increments (Reibisch 1899). In addition to measuring age and growth, otolith morphometry has revealed information ranging from taxonomic diversity in contemporary and ancient assemblages, population mixing and evolutionary relationships among species. The analysis of otolith chemistry has also become a method of choice to reconstruct lifetime migration patterns, natal origins and connectivity patterns, environmental histories and trophic interactions in marine and freshwater systems alike. The otolith is thus an invaluable repository of information useful for unravelling questions about demographics, population structure, ecosystem interactions and impacts of environmental stressors. Insights gleaned from otoliths help improve our understanding of ecological dynamics of diverse taxa and inform management practices for artisanal to industrial fisheries worldwide. Many of the analytical methodologies developed for otoliths have been further applied to other calcified structures in aquatic organisms, e.g. scales, bones, statoliths, that provide analogous biological, ecological and environmental information. The International Otolith Symposium (IOS) series has served as a platform for otolith researchers to communicate recent developments and advances starting with the first IOS in 1993 in the US, followed by IOS held in Norway, Australia, USA and Spain, and have been held every 4–5 years. The latest in this series was the Sixth International Otolith Symposium held on 15–20 April 2018 in Keelung, Taiwan, which was the first time an IOS has been convened in Asia. This symposium was hosted by National Taiwan Ocean University and the participants included 234 scientists from 37 countries with a total of 239 oral and poster presentations.