Fish mislabelled as sustainable, researchers find

The findings, published in the journal Current Biology, raise serious questions about the reliability of the chain of custody certification system overseen by the MSC.

Amy Jackson, deputy standards director at the MSC, announced an immediate investigation and said the organisation, which is widely considered to run the gold standard of fish eco-labelling, was “very concerned” about the findings by scientists.

“Our investigation will identify if any breach has occurred and pinpoint exactly where in the supply chain it happened. If proven, it could result in the suspension or withdrawal of their chain of custody certificate,” she said.

Dr Peter Marko, of Clemson University and one of the researchers involved in the study, said: "Fish are being sold that are improperly labelled. We found that, for fish purchased in US groceries, not all those labeled as MSC-certified Chilean sea bass are actually MSC-certified Chilean sea bass.

"The simplest explanation for this result is that other species plus Chilean sea bass from other, uncertified fisheries are being added to the supply chain for MSC-certified Chilean sea bass.

“There is no question that organizations like the Marine Stewardship Council are trying their best to guide consumers to sustainably harvested seafood, but it is currently difficult to guarantee the geographic origins of fish. At a grocery or on a plate in a restaurant, Chilean sea bass from South Georgia looks the same as Chilean sea bass from other parts of the world.”

In conducting the study the research team from Clemson University, Florida Atlantic University and the National Oceanic and Atmospheric Administration purchased 33 Patagonian toothfish from stores in eight US states and identified their mitrochondrial DNA which allowed them to work out which fisheries they had originated from.