Tracking the provenance of octopus using isotopic and multi-elemental analysis.

• Provenance and traceability tools can support long-term seafood security. • Traceability techniques have been little tested for octopus. • A novel combination of statolith isotopes and soft-tissue elements were analysed. • Chemical profiling accurately identified origins of octopus, even across species. • This technique can support accountability and sustainability of seafood. Octopus play an increasingly important role in ocean ecosystems and global fisheries, yet techniques for authenticating provenance are sorely lacking. For the first time, we investigate whether chemical profiling can distinguish geographical origins of octopus on international and domestic scales. Our samples consisted of wild-caught octopus from south-east Asia and southern Australia, regions with high seafood trade. We used a novel combination of stable carbon (δ13C) and oxygen (δ18O) isotope analyses (Isotope-Ratio Mass Spectrometry) of internal calcified structures called statoliths, with elemental analyses (X-Ray Fluorescence using Itrax) of soft-tissue. We found that multivariate profiles exhibited distinctive regional signatures, even across species, with high classification success (∼95%) back to region of origin. This study validates isotopic and multi-elemental profiling as an effective provenance tool for octopus, which could be used to support transparency and accountability of seafood supply chains and thus encourage sustainable use of ocean resources. [ABSTRACT FROM AUTHOR]