The relevance of otoliths
The importance of using otoliths when studying fish populations has been extensively documented in the literature; over the last 30 years, it has become entirely possible to understand the birth, growth, age and mortality of species studied through those structures (Jones, 2009). However, according to this author, minimal attention has been focused on the comparison of the structures between species or families, although such differences are noticeable showing the life patterns, resilience, susceptibility to fishing and changes due to anthropogenic causes.
Numerous studies have been presented by renowned scientists allowing to assess multiple applications of the otolith studies in many fields, including taxonomy, phylogeny, comparisons of lifespans and energy budgets in different fish populations, and studies investigating the chronology of direct (metabolism) or indirect (food resource availability) environmental events, larval dispersion, larval periods and mortality, recruitment failure, larval retention patterns, exposure of fish to contaminants, anthropogenic processes (which cause changes in the abundance and diversity of the components in an ecosystem), bio-markers of environmental pulses/changes, effects of protected areas in the fishery management, determination of the origin of species, diversity of environmental colonization, introduction and invasion of new species, identification of the fish in the diet of other species, metamorphosis, proportion of distinct populations, life history, geolocation (retrospective displacement studies, especially for estuarine fishes), archeology, physiology, contamination (by selenium and mercury), phylogenetic relationships, characteristics of the otoliths and trophic niches, ecomorphology, effects of a changing in the diet (in aquaculture), panmixia, transoceanic migrations, signs of nesting and nursery areas, reconstruction of the migration of juveniles, segregation, parasitism, the understanding of the state of the fisheries (in time series), trophic position, differentiation between forms of species whether living in shallow or deep waters, population structures, mortality estimation (natural tags), and population connectivity. Additionally, it is relevant to mention their importance in measuring climate changes caused by acidification of the oceans, as presented in a study published in the Science magazine, Checkley et al. (2009).