Traceability of the Norway Lobster nephrops norvegicus in UK Shelf Seas: A stable isotope approach

Ensuring sustainability of the world fisheries is a key conservation and economic objective. Traceability of seafood from the final sale back to the point of harvest is an important aspect, supporting both fishery management and consumer protection. Stable isotope–based geolocation can be applied to trace the spatial origin of seafood, drawing on comparisons between the isotopic compositions of the product and those of a reference dataset from known spatial locations. This study tests the extent to which stable isotope–based geolocation can be applied to identify catch location of the Norwegian lobster Nephrops norvegicus. Carbon, nitrogen, and sulfur isoscapes across UK shelf seas are used as the reference dataset and test the accuracy of assignment estimates using a variety of bivariate and multivariate stable isotope geolocation approaches. Two alternative Bayesian inversions, one balanced and one weighted, are applied to the outcomes of the statistical models to determine the most accurate methods of assignment. Of all the methods trialed, the multivariate approach using carbon, nitrogen, and sulfur isoscape data produced the most accurate assignments, with c. 60% of samples from each site correctly assigned among six possible fishery origins. Weighted Bayesian approaches resulted in more correct assignments to highly fished sites, but at a cost of reduced correct assignments to sites of low fishing activity. Processed Nephrops samples obtained from supermarkets were assigned to potential fishery location, with results indicating the majority were captured in the west of Scotland. The isoscape methods explored can be calibrated to any marine feeding organism and provide a useful tool for more efficient management of marine stocks