Patterns and implications of seafood substitution
The decline and collapse of many of the world's fisheries has led to widespread concern about where our seafood comes from. Although extensive fisheries exploitation now has consumers eating down the marine food web, many consumers are not fully aware of this due to “seafood substitutions,” in which less valuable fish are mislabeled and sold under the names of more expensive ones. Although consumer fraud is one obvious consequence of these substitutions, mislabeling of overexploited species also creates the false impression for consumers that many overfished threatened species are actually plentiful in their local groceries.
Our lab used a molecular genetic forensic approach to invetigate patterns of seafood substitutions in two species, red snapper (Lutjanus campechanus) and Chilean sea bass (Dissostichus eleginoides). In red snapper we found that >75% of fish sold under the name Red Snapper (the U.S. Food and Drug Administration's legally designated common name for Lutjanus campechanus) are in fact other species. Another startling fact that emerged from this study was that some of the fish sold as Red Snapper were rare snapper species not yet catalogued in genetic databases. Many other similar studies have been done since, which were summarized in a recent (2011) report from Oceana.
For Chilean sea bass, we tested whether fish sold in groceries with labels from the Marine Stewardship Council (MSC) were actually harvested from the only fishery that has been certified by the MSC as a sustainable stock. In addition to species substitutions, we also found that among fish that were actually Chilean sea bass, 15% possessed mitochondrial DNA (mtDNA) variants (haplotypes) that have never been found before in the certified fishery. The simplest explantion for our results is that fish from uncertified fisheries are being added to the supply chain for MSC certified Chilean sea bass. Although social marketing of seafood like certified sustainable Chilean sea bass could be a useful tool directing consumers towards sustainable fisheries, our study shows that the mislabeling of Chilean sea bass undermines this basic conservation goal.
Want to see the data from this study? Detailed description of our analyses and haplotype gel images can be obtained here.
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Marko, P. B., Nance, H. A., and K. D. Guynn. 2011. Genetic detection of mislabeled fish from a certified sustainable fishery. Current Biology 21: R621-R622. [PDF]
Marko, P. B., Nance, H. A., and K. D. Guynn. 2012. Seafood mislabeling: a response to Mariani. Frontiers in Ecology and the Environment 10: 10-11. [PDF]
Marko, P. B., S. C. Lee, A. M. Rice, J. M. Gramling, T. M. Fitzhenry, J. S. McAlistar, G. R. Harper, A. L. Moran. 2004. Mislabeling in a depleted reef fish. Nature 430:309. [PDF]