Spatiotemporal Variability of Trace Elements Fingerprints in Otoliths of Japanese Eel (Anguilla japonica) and Its Use in Tracing Geographic Origin

SIMPLE SUMMARY: Discrimination of geographic origins in seafood is crucial to safeguard and control food security and quality for consumers. We could successfully discriminate the origins of wild and cultured freshwater eel, Anguilla japonica, which is one of the most valuable fish in East Asia with high market demand, by means of trace elements’ fingerprints (TEF) in the otoliths. Spatiotemporal variability of TEF was examined in the eels collected in wild and cultured environments in East Asia. Discriminant function analysis showed less temporal variation but high spatial variation, suggesting that otolith TEF reflect each habitat or aquaculture environment. The otolith TEF can be a reliable tool to discriminate the geographic origin of the fish. ABSTRACT: To secure traceability along supply chains of foodstuffs, the spatiotemporal variability of trace elements’ fingerprints (TEF) in fish otoliths provides a powerful tool to determine and discriminate the origin. Spatiotemporal variability of TEF was examined in a commercially important seafood, Japanese eel (Anguilla japonica), by means of laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). Six elemental ratios (Na:Ca, Mg:Ca, P:Ca, K:Ca, Sr:Ca, and Ba:Ca) were determined in the otoliths of specimens originating from four aquaculture farms to examine the spatial variability and from one wild habitat over three years to examine the temporal variation. Significant temporal variation was found in Mg:Ca and Sr:Ca ratios; however, discriminant function analysis showed a lower temporal variation (50%) for the three years. Spatial variations were significant in Sr:Ca and Ba:Ca ratios, and discriminant function analysis showed high (80%) spatial variation among the four farms. Otolith TEF in the Japanese eel showed specific spatial variation among aquaculture farms but intangible temporal variation, suggesting the otolith TEF reflect each aquaculture environment. The present study shows that otolith TEF can be a reliable tool to discriminate the geographic origin of the Japanese eel.