Trust The Label?

It’s not easy eating green. Despite extensive and often successful efforts to accurately label “sustainable” fish, a new genetics study suggests that some seafood traders are duping consumers into buying fraudulent flesh. Nearly one-quarter of a sample of supposedly certified “Chilean sea bass” were “actually other species” or not definitively taken from an approved fishery, researchers report.

Although “the results are not exactly shocking,” they do “point to a problem with the supply chain,” says Peter Marko of Clemson University in South Carolina, a lead author of the Current Biology study.

For decades, some conservationists have been trying to push both consumers and producers of fish, wood, and other natural products to adopt more sustainable practices by certifying and prominently labeling products that come from environmentally-sound sources. Consumers get the benefit of knowing that a third-party has confirmed that their purchase is better than some of the alternatives, and sellers can sometimes charge more for certified products.

But labeling efforts have long been bedeviled by long “chains of custody” that offer plenty of possibilities for fraud and fakery as a product moves from source to middlemen to stores. Traders have routinely relabeled questionable timber and fish, for instance, to avoid problems and generate higher profits.

This time, the victim is the Marine Stewardship Council, a high-profile effort to certify sustainable fisheries. One of their targets: the Chilean sea bass industry, which targets tasty but slow-growing, deep water fish from the oceans off of South America. The group has certified sea bass from just one fishery – located near the sub-Antarctic island of South Georgia and a nearby plateau called Shag Rocks — to carry its label.

When Marko’s team analyzed the mitochondrial DNA from MSC-certified bass purchased at retail outlets in eight U.S. states, however, they found the genes didn’t always fit. Eight percent of 36 fish weren’t sea bass at all. And of the fish that were truly bass, about 15 percent carried mitochondrial DNA variants that are not known from the South Georgia/Shag Rocks population. One sample carried a variant that has been found only on the other side of the globe, in the southern Indian Ocean. It’s not clear “where and how the uncertified fish reach market,” Marko says.

“There is no question that organizations like the Marine Stewardship Council are trying their best to guide consumers to sustainably harvested seafood,” he adds. “But it is currently difficult to guarantee the geographic origins of fish.” The MSC has been working on ways to confirm fishes’ origins, he says, and the new study may serve as a model for how to go about that.

In the meantime, consumers worried about where their sea bass is really coming from have only one easy way to get off the hook: Take it off the menu. David Malakoff | August 22, 2011

Source: Marko, Peter B. et al. (2011). Genetic detection of mislabeled fish from a certified sustainable fishery. Current Biology doi:10.1016/j.cub.2011.07.006

Image © Andreas Gradin |