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Fish DNA Detective Looks At What's On The Menu

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Fish DNA Detective Looks At What's On The Menu


Fish DNA Detective Looks At What's On The Menu

Fish DNA Detective Looks At What's On The Menu

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

Mahmood Shivji, a professor of conservation biology at Nova Southeastern University and director of the Guy Harvey Research Institute, analyzed the DNA of more than 150 fish served at restaurants, and found many of them secretly substituted a cheaper fish for one advertised on the menu. Shivji says he finds that the "restaurant fish CSI work" makes for a good teaching tool.


We learned a couple of years ago about the work of Professor Mahmood Shivji at the Guy Harvey Research Institute in Fort Lauderdale, Florida. Professor Shivji teaches conservation biology, including a course in genetics.

And in 2007, at the urging of a local TV station, he tested the DNA of seafood that was sold at local restaurants as grouper. And he discovered it was cheaper fish: catfish or tilapia. Well, since then, Professor Shivji has been called in to sample seafood all over the country: in Philadelphia, Charlotte, Kansas City. And he's also gone beyond grouper. And, Professor Shivji, I think that we can now say that you are America's leading fish detective.

Professor MAHMOOD SHIVJI (Guy Harvey Research Institute): Oh, well, I'm flattered. Thank you.

(Soundbite of laughter)

SIEGEL: Okay. First of all, I want you tell us about the case of the red snapper on the menu in Kansas City.

Prof. SHIVJI: Well, you know, the Kansas City NBC television station went and sampled 20 restaurants in the Kansas City area. And of those 20, they sampled 15 menu items that were labeled red snapper. And, of course, we didn't know what they were supposed to be. And when we returned the results of them, it turned out that only one out of the 15 was actually authentic red snapper. So 14 were mislabeled items. It was quite amazing.

SIEGEL: Yeah. This has become an annual class exercise for you on DNA extraction, I gather.

Prof. SHIVJI: Yes. You know, it's actually been quite interesting. I mean, I found this sort of a restaurant fish CSI work makes for a rather good teaching tool in my undergraduate classes.

SIEGEL: This would not be an academic exercise. But I'm wondering, can you imagine your research squaring off against some panel of noted chefs or gourmands to see if they can tell the difference between fish that's being sold as grouper or that really is grouper.

Prof. SHIVJI: Well, you know, DNA doesn't lie. It's a very powerful tool and that's why they use it in human forensics as well. Having said that, I mean, there are clearly people that can tell just by looking at the product, or usually actually by eating it, whether it's a grouper or a snapper or something else.

But there are relatively few people who can do that. And, you know, the argument has been made that the vast majority of consumers can't tell the difference. So what's the big deal, really, you know?

SIEGEL: Yeah, it seems that a lot of people are buying fish for name.

Prof. SHIVJI: Oh, very much so. You know, unfortunately, this mislabeling is not a harmless sort of endeavor, you know. I mean, first of all, it's dishonest business practice and consumer fraud and it's illegal.

But really, from my perspective, what is equally important - although I think less appreciated - is that all this common mislabeling on menus gives consumers the erroneous perception that groupers and red snapper are abundant in the ocean, when the reality is that these species are severely overfished and in serious need of better management and conservation efforts.

SIEGEL: Do you think, by the way, that the restaurants that are serving whatever it might be, tilapia or catfish, and calling it grouper, do you assume they're doing that knowingly? Or is there any room for error on the wholesale level here?

Prof. SHIVJI: I think it's a mixed bag. You know, we've done enough of these cases now to sort of come to realize that some restaurant owners simply don't know and they're actually being fooled by the distributors. In other cases, we have found situations where the restaurant actually knows, and they actually have boxes in the back called tilapia, which they're then selling as grouper.

SIEGEL: Has this turned - in your professional and your academic career - has it altered your own ordering habits when you go out to eat at a restaurant?

Prof. SHIVJI: Oh, absolutely. You know, and it's not the mislabeling that's the main reason. It's just that as a conservation biologist, I am well-aware of all the overfishing issues. And so I never order grouper or snapper or swordfish on the menu, because these are, you know, these fish are in trouble. But now, knowing about the mislabeling on top of that, you know, clearly it's - you know, I stay away from it.

SIEGEL: But given what you've found, you could ask the waiter: that grouper on the menu, is that grouper or is it, you know, is it actually catfish?

Prof. SHIVJI: I do routinely, believe me. You know, when it's on the menu, I'll, you know, I'm not going to order it, but I'll actually ask. And, of course, the response is, oh yes, of course it's grouper.


Prof. SHIVJI: And then sometimes I'll take a sample and test it and much of the time it's not.

SIEGEL: You mean from your own dining you'll come back.

Prof. SHIVJI: Yeah, say, if I'm with a group of people and somebody has ordered that dish, for example, I'll just, you know, steal a small piece and take it back to the lab. But I won't order it myself.

SIEGEL: Well, have they got your picture up in the kitchen of all the seafood restaurants in South Florida now?

(Soundbite of laughter)

Prof. SHIVJI: Oh, you know, I don't know yet. They haven't let me back in the kitchens. But, hmm, I better be careful here.

SIEGEL: Well, Professor Shivji - that's Professor Mahmood Shivji, who teaches conservation biology at the Guy Harvey Research Institute of Nova Southeastern University in South Florida. Thanks a lot for talking with us.

Prof. SHIVJI: Thank you so much.

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