Significance of otolith in freshwater fish migration studies and sustainable fisheries management

Otoliths are the calcium carbonate structures within the inner ear of teleost fish, composed of three pairs - sagitta, lapillus, and asteriscus. These structures grow through the periodic deposition of calcium carbonate and protein layers. Because otoliths are metabolically inert and not subject to resorption, the growth rings (annuli) and incorporated chemical signatures in it remain permanent throughout the life cycle of the fish. As permanent biological archives that begin developing before hatching, otoliths offer an efficient and robust method for biogeographical reconstruction providing critical data for the effective management and conservation of fish populations.