Published online 22 August 2011 | Nature | doi:10.1038/news.2011.496

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Seafood suffers from fishy eco-labelling

Chilean sea bass certified 'green' aren't necessarily so.

Patagonian toothfishPatagonian toothfish (Dissostichus eleginoides) take years to grow to maturity and are susceptible to overfishing.Paul Sutherland/National Geographic/Getty Images

Some Chilean sea bass labelled in shops as sustainable are not what they claim to be, researchers have found. In a study published today in Current Biology1, some fish bearing an eco-label were found not to come from the certified fishery; others weren't Chilean sea bass at all.

Patagonian toothfish (Dissostichus eleginoides), marketed as 'Chilean sea bass', became popular with consumers for their buttery flavour and tender, flaky texture. The fish live for up to 50 years in the deep, frigid waters surrounding Antarctica, and take 10-20 years to reach maturity, so they are vulnerable to over-fishing.

Catching them "is not like fishing for fish — it's almost like logging for trees", says Stephen Palumbi, a marine population biologist at Stanford University in California, who was not involved with the study. "It takes that long for these fish to grow up and be ready for market. That's why the fish got in trouble."

By the 1990s, illegal and unregulated fishing had so depleted stocks of the fish that they were widely regarded as unsustainable. The eco-conscious US grocery chain Whole Foods stopped selling Chilean sea bass in 1999, and Seafood Watch, a guide to sustainable seafood run by the Monterey Bay Aquarium in California, recommended that consumers avoid the fish.

But the Marine Stewardship Council (MSC), a London-based international non-profit organization that promotes sustainable fishing, says that one particular population of Patagonian toothfish can be sustainably harvested: that in the sub-Antarctic waters around the island of South Georgia. As such, fish harvested from this population bear an MSC 'eco-label' that indicates to consumers that the fish they are buying is sustainable. In 2006, Whole Foods became the first retailer in the world to carry the MSC-certified Chilean sea bass. Other retailers followed suit.

The Patagonian toothfish is not listed as threatened or endangered, but "the spectre of the amount of illegal and unregulated fishing relative to legal and regulated fishing has people worried", says Peter Marko, a population biologist at Clemson University in South Carolina and lead author of the latest study.

Bait and switch

Marko and his colleagues wanted to know whether Chilean sea bass that carry the MSC eco-label do actually come from the certified fishery. The researchers collected fish bearing the label from supermarkets across the United States and compared the DNA of the samples with known sequences from the South Georgia population. They also collected Chilean sea bass not carrying the eco-label.

The teams found that 8% of the 36 eco-labelled fish tested were not Patagonian toothfish, but were in fact other species. Of those that were the right species, the genetic data suggested that 15% did not come from the certified population.

"The mislabelling causes consumers to unwittingly buy fish from uncertified fisheries," says Marko. But where the breakdown in the supply chain is occurring is anyone's guess, he adds.

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The finding is "a major black eye for the MSC", says Palumbi. The council "prides themselves on what they call the 'chain of custody', and all their management decisions are based on their being able to manage this. These data show that the existence of that legal market provides cover for the sale of unsustainably caught fish."

But Stefano Mariani, a marine population biologist at University College Dublin, cautions against drawing too strong a conclusion about the integrity of the MSC's certification process. He notes that the number of fish tested was relatively small, and knowledge about mixing and distribution of fish species is still limited. He also points out that a much higher proportion — 32% — of non-certified fish than eco-labelled ones were species other than Patagonian toothfish.

"At the end of the day," says Mariani, "if you're desperate to eat Chilean sea bass, buying a product that is MSC-certified is still the best option." 

  • References

    1. Marko, P. B., Nance, H. A. & Guynn, K. D. Curr. Biol. 21, R621-R622 (2011). | Article |
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