Shrimp (sub-)national traceability and retail fraud detection using stable isotopes and multi-element profiling

Credible seafood traceability is essential to supporting sustainability claims and enforcing import regulations designed to prevent environmental degradation and fraud. In this study, we evaluate the potential of combining stable isotope ratio and multi-elemental analyses to determine the geographic origin of whiteleg shrimp ( Litopenaeus vannamei ) meat from Ecuador (n = 191), Honduras (n = 118), and Thailand (n = 66). Reference samples of shrimp meat, telson (n = 32), pond water (n = 32), and feed (n = 32) were analyzed using isotope ratio mass spectrometry (IRMS) (δ 2 H, δ 13 C, δ 15 N, δ 18 O, δ 34 S) and inductively coupled plasma mass spectrometry (ICP-MS) for elemental profiling. We assessed the extent to which chemically processed samples, to mimic commercial conditions, and retail samples retained their multivariate and elemental profiles comparable to reference samples. Random forest models demonstrated high accuracy for country-level classification of reference shrimp (out-of-bag error = 0.47%) and retained strong predictive power at subnational catchment levels for Ecuador and Honduras (OOB = 3.08–5.32%). Importantly, treated shrimp retained chemical fingerprints comparable to their reference shrimp meat counterparts, achieving a 100% successful assignment to subnational areas. However, retail products exhibited low assignment accuracy (16%), suggesting either post-processing alteration or false/fraudulent labeling of origin. Spearman tests among shrimp meat, telson, feed, and water revealed strong isotopic and elemental correlations. The telson samples were correctly classified to their country of origin when tested against reference models built from shrimp meat data, demonstrating that telson shell chemistry reliably mirrors the geographic signature of the edible tissue.