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A fishy tale for the origins of some MCS Chilean sea bass

By Martin Leggett - 22 Aug 2011 16:2:57 GMT
A fishy tale for the origins of some MCS Chilean sea bass

For those wanting to tread a little lighter upon the oceans, that little-blue MCS (Marine Conservation Society) label on their sea-food stands out as a beacon of hope. Sea-food that has been MCS-certified should only come from those fisheries that have met stringent tests to make sure they are being fished sustainably.

But new genetic research, looking to pinpoint the make-up of a MCS-certified fish stock commonly found in US grocery stores - Chilean sea bass - has shown that good intentions don't always stack up. It turns out that a worrying proportion of these Chilean sea-bass aren't sustainably fished, have never been near South America - and that some are not actually even sea-bass. The work is being published tomorrow in the journal Current Biology.

They all look same to me

Chilean sea-bass can only display the MCS label - showing that they being fished in a way that allows stocks to grow healthily, and avoids the tragic toll of bycatch - if they come from the Shag Rocks fishery of the South Atlantic. That is the only sustainable Chilean sea bass fishery, which lies in the cold waters off of South Georgia, on the margins of the Antarctic.

However, one man's sustainable sea-bass looks identical to anothers unsustainably fished one, making assessing claims of sustainability difficult. The paper's lead author, Peter Marko of South Carolina's Clemson University, said that '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.' However, sea bass coming from the Shag Rock sustainable fishery do have a distinctive genetic fingerprint.

Well-travelled, but badly fished?

That allowed the team behind the paper to test whether the fish found in fishmonger's aisles, across the US, really were the sustainable Chilean sea bass or not. Unfortunately, the results were a mixed bag. At least 15% of the sea bass were flagged as being from different areas - many appearing to come from nearby South American waters around the Falkland Isles; at least one sample came all the way from the southern Indian Ocean. And some of the fish even turned out not to be sea bass at all.

Marko believes the long route from fish-net to food-stall offers plenty of opportunity for slipping in the unwelcome, and unsustainably-sourced, fish. '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 MCS-certified Chilean sea bass.' He doesn't think that the MCS are being negligent, but more needs to be done.

MCS 'trying their best'

"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." He hopes that the wider use of testing along the supply chain, similar to those used in this study, will help the MCS get on top of this embarrassing problem.

In the meantime, consumers may ask whether it is a good idea to keep MCS Chilean sea bass on their weekly shopping list. The paper does confirm that at least three-quarters of the fish tested were from the MCS accredited fishery. That may suggest that if you want to keep it sustainable, and an alternative source of such sea-food isn't to hand, the Chilean sea bass might still earn a place on your dish.

Top Image Credit: Sea-bass © Alex Raths