Face-off: Shark or pork? DNA barcoding authentication and labelling analysis of shark products (intestine and stomach) available on Chinese e-commerce

Systematic monitoring of the shark product supply chain is essential to ensure traceability, uphold consumer transparency, and contribute to species conservation. In this study, 69 shark products, 48 shark stomachs (SH_s) and 21 shark intestines (SH_i), were sourced from Chinese e-commerce platforms. First, information to consumers was evaluated by 1) analyzing data provided on the product web page and 2) assessing the products label compliance with the current Chinese labelling standard (GB7718-2011); then the products were molecularly authenticated by DNA barcoding to assess eventual substitution cases. An inaccurate presentation to consumers was highlighted for all products, being exclusively designated by their general trade names, without reference to scientific name, or other details that would facilitate the products characterization. DNA barcoding results confirmed the allocation of 40.6 % of the products to Prionace glauca (blue shark) and, of 59.4 % of products to Sus scrofa (pork), in a clear instance of substitution-based adulteration. This case represents an unprecedented incident of a total substitution of a seafood product with a non-aquatic animal product. This result not only raises concerns about economically motivated fraud but also underscores a significant violation of consumer rights and the protection of ethically or religiously driven dietary choices. Finally, potential public health issues associated with biological or chemical risk linked to farmed animals must not be disregarded. This evidence, when considered in conjunction with the absence of specific regulatory oversight for non-prepackaged food and seafood labelling, serves to emphasize the challenges and the urge in ensuring product traceability, consumer protection, and sustainability in the seafood supply chain.