Differentiating wild, lake-farmed and pond-farmed carp using stable isotope and multi-element analysis of fish scales with chemometrics.

Stable carbon (δC) and nitrogen (δN) isotope ratios and multi-element signatures of pooled fish scales were used to differentiate wild, lake-farmed and pond-farmed carp from Dongting Lake, China. Fish scales were found to be important archives for the dietary history and trophic level of wild and farmed fish, indicating their food sources. δC and δN values of pond-farmed carp scales were comparatively enriched to wild and lake-farmed carp due to their animal protein-derived feeds. Multi-element compositions of fish scales also showed significant differences between wild and farmed fish. A partial least squares discriminant analysis (PLS-DA) model correctly discriminated the three carp groups. Discrimination accuracies of wild, lake-farmed and pond-farmed carp were 100%, 95%, and 100% for the training set, and 100% for the testing set. This strategy provides a promising non-lethal alternative method to combat mislabeling of freshwater carp from different farming methods.