The last mile challenge: Certified seafood and federal labeling laws out of sync at the end of the supply chain in Los Angeles, California.

Seafood certification programs aim to aid consumers in identifying products with reduced environmental impacts and assure accuracy in labeling and traceability, complementary to or in the absence of governmental regulatory action. The most widely recognized seafood certification program is led by the Marine Stewardship Council (MSC), whose Chain of Custody Standard emphasizes accuracy in fish sourcing from harvest to retail using tracebacks and audits. Here explicit testing was conducted on the labeling accuracy of MSC-certified seafood sold in the world’s second largest seafood importing market, the United States, per stringent application of federal labeling laws. Samples of commonly sold MSC-certified fresh fish were collected from processors (123) and grocers (149) in Los Angeles, California from 2017 to 2019 and identified to species using DNA barcoding. Grocers’ mislabeling rates were statistically higher than those of processors. Most mislabeling was attributed to substitution among congeners or labeling with invalid FDA names. Data-driven recommendations include regular DNA-based testing and greater harmonization between certification programs and federal guidelines, particularly in coordination with supply chain end vendors