Improving the traceability of farmed and wild-caught aquatic species: A review of current applied analytical techniques with emphasis on isotopic biomarkers

Many species of aquatic organisms are currently overexploited and listed as vulnerable groups by the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Some of these aquatic species can now be produced by means of aquaculture methods and are traded as farmed products. Such products are not subject to fishing bans and under these scenarios, a delicate balance exists between the conservation of natural resources and the trade of farmed, albeit protected species. Traceability methods are becoming intrinsic components of protocols aimed to improve seafood supply chains. In addition to their role in natural resource management, traceability methods represent important tools in food innocuity issues given that they assist in guaranteeing food provenance and product inclusion into food safety processes. The implementation of effective traceability protocols reduces malpractices such as product mislabeling and illegal fishing. The latter encompasses social connotations for the legally established fishermen and farmers, who are better protected against the unfair competition exerted by illegally caught seafood. The dietary history of organisms affects the chemical characteristics of their tissues. These chemical characteristics can be measured by means of several analytical methods and used as reliable biomarkers to determine production method and geographical origin. The present review explores traditional, emerging, and combined analytical techniques that support the traceability processes of fish, mollusks, echinoderms, crustaceans and other groups of edible and ornamental aquatic organisms. An emphasis is placed on the application of stable isotopes analysis as a useful tool to distinguish farmed from wild aquatic organisms and to determine the provenance of seafood products.