Wild-caught seafood is vulnerable to illegal, unreported, and unregulated fishing, which often leads to overfishing and destruction of marine environments. A recent study has developed a method to determine the geographical origin of seafood using oxygen isotope (δ18O) composition imprinted in the shells and bones of seafood (δ18Obiomin). This value is determined by ocean composition and temperature rather than the seafood's biology. Global ocean isoscapes of predicted δ18Obiomin values specific to fish (otoliths), cephalopod (statoliths) and shellfish (shells), and a fourth combined “universal” isoscape, were evaluated in their ability to derive δ18Obiomin values among known-origin samples. After validation and testing of the method, it was demonstrated that this global isoscape can be used to correctly identify the origins of a wide range of marine animals living in different latitudes. After removing tuna species from the analyses, a prediction rate of up to 90% in classifying fish, cephalopods, and shellfish between the tropical waters of Southeast Asia and the cooler waters of southern Australia was obtained. Further research is planned to incorporate other chemical markers into improving the prediction of geographical origin.
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