Fish species mislabelling in China: evidence from a survey of frozen, dried, and surimi-based fish products marketed as cod-related species.

'Cod'-related species are among the most appreciated marine fish resources around the world, but are also prone to species mislabelling. In the present study, a total of 76 frozen, dried, and surimi-based fish products, sold as 'Cod' (59 products), 'Atlantic authentic Cod' (11 products), and 'Authentic Cod' (6 products), were collected in China. A species-specific LAMP (loop-mediated isothermal amplification) method was used to screen for the presence of Atlantic cod (Gadus morhua), Pacific cod (G. macrocephalus), Alaska pollock (G. chalcogrammus), Southern hake (Merluccius australis), which was cross-confirmed using real-time PCR and DNA sequencing methods. The results highlighted the greatest species diversity for 'Cod' products, and the identified species were from nine different families. It appears that the practice of assigning a specific type or category of species to the common name 'Cod' has not been widely advocated, and the misuse of this ambiguous common name has been a common practice for species adulteration, negatively impacting consumers' rights and marine conservation. To rebuild consumers' confidence, retail fish suppliers have differentiated their products by adding specific qualifiers in front of the common name 'Cod' on the label, such as 'Authentic cod' and 'Atlantic authentic cod'. The endeavour is highly meaningful, since Gadus morhua was identified as the species for a significant majority of 'Atlantic authentic cod' and 'Authentic cod' products (64.7%, 11/17), with the remaining six products identified as Alaskan pollock (G. chalcogrammus), Pacific cod (G. macrocephalus) and North Pacific hake (Merluccius productus). Despite the positive effort to reverse species mislabelling from retail on-line fish suppliers, a standardized fish nomenclature stipulated by the responsible authorities remains crucial for enhancing transparency and continuing to reduce species mislabelling.