Abstract: A total of 16 salmon samples from the major salmon exporters (Faroe Islands, Norway, Chile, Canada, and Australia) to China collected at Shenzhen Port, together with two rainbow trout samples produced in China, were analyzed for carbon, nitrogen, hydrogen, oxygen, sulfur stable isotope ratios in the muscle, skin, scales, and bones. The difference in isotopic distribution among tissues and geographical origins was compared. The discriminant analysis (DA) was employed for differentiating salmon from different geographical origins. There were significant differences in the isotopes of carbon, nitrogen, sulfur and hydrogen and oxygen among salmon from different geographical origins. Obvious isotopic fractionation effect was observed among different tissues. The scale and skin isotope ratios were more effective geographical origin indicators than the muscle and bone isotope ratios. The DA results showed that stable isotopes could be used to completely discriminate among the five geographical origins of salmon and also to distinguish Chinese rainbow trout from imported salmon. The geographical origins of six salmon samples randomly purchased from the market were successfully traced by the stable isotope technique. The method developed in this study can be used to trace the geographical origin of salmon products, which will provide technical support for ensuring food safety and consumer health.

Key words: Atlantic salmon; rainbow trout; chemometrics; geographical origin traceability; stable isotopes