In this context

In this context, natural chemical tags present in certain tissues, such as the inner ear bones of teleost fish (otoliths), are a promising alternative.
The unique properties of these calcified pair structures render them especially useful to unravel the life-history characteristics and movement patterns of fish (Campana & Thorrold, 2001; Walther & Thorrold, 2011). Otoliths grow continuously throughout the life of the fish (from birth to death), are acellular metabolically inert materials and the concentration of certain accreted elements in the successive growth layers is largely determined by their concentration in the ambient water (Campana, 1999; Bath et al., 2000; Walther & Thorrold, 2006; Morais & Daverat, 2016). Therefore, if there are natal habitats with different chemical signatures, the otolith core of the fish hatched in them will record for life these differences, allowing the retrospectively determination of natal origin (Thorrold et al., 2001).