Optimizing tissue and tracer selection for improving the traceability of aquaculture fish and prawns

Abstract Geographic traceability of seafood products is essential for seafood authentication, sustainability, and biosecurity. Elemental profiling is often used to differentiate geographic origins of aquatic species due to relatively fine-scale spatial differences in environmental trace elements. However, regional differences in the trace element profiles of marine consumers are often difficult to distinguish due to species-specific regulation, metabolism, and accumulation processes. This study assessed the influence of tissue selection and tracer combinations on the geographic traceability of farmed Barramundi ( Lates calcarifer ) and Black Tiger Prawns ( Penaeus monodon ) across chemically distinct regions in Australia. Trace elements (TE) were analyzed in pond and estuary water, feed, and animal tissues including muscle, gill, liver, and kidney of fish and muscle, gill, and pleopods of prawns. Stable isotopes (SI) of C, N, and S were analyzed in feed and animal muscle samples. Regional differences in water chemistry were observed, and ponds had similar TE profiles to nearby estuaries. Different feed brands also varied in their TE composition. Multivariate analyses indicated that metabolically active fish tissues such as liver show clear separation of samples by geographic region and excellent discriminatory power. For prawns, pleopods yielded similar discriminatory power to muscle, indicating the potential use of pleopods as a non-lethal sampling alternative. Increasing sample size or combining TE and SI tracers are both suitable options for improving origin assignment of muscle samples. These findings provide practical guidance for optimizing tissue selection and sampling design in elemental profiling studies.