Tuesday, April 17, 2012

Practical uses for DNA sequencing

Although we at KGI focus on genomic sequencing as an antecedent to the Brave New World of genomic medicine, in the mass market it’s probably best known for “Finding Your Roots.” However, the LA Times (and the Boston Globe before it) report on a much more direct impact on the average consumer: fish fraud.

As the Times reports
Tests on seafood sold at Los Angeles sushi bars, restaurants and grocery stores have revealed that more than half is not labeled correctly, [Oceana] a nonprofit organization is reporting today.

The U.S. Food and Drug Administration prohibits so-called species substitution. Still, the practice remains prevalent. Consumer Reports found that 18% of seafood samples its researchers collected from retail stores and restaurants on the East Coast last year was mislabeled. A 2011 investigation by the Boston Globe reported that 48% of the fish it collected from Boston restaurants, grocery stores and seafood markets was sold with the wrong species name.

FDA spokesman Douglas Karas said the agency is working to determine how often, or at what point in the supply chain, fish substitution occurs. Most of the seafood fraud complaints the FDA receives come from consumers at the retail level, Karas said. The FDA is conducting a yearlong DNA test of about 800 fish collected across the nation.

In the L.A. samples, red snapper was misidentified 100% of the time, DNA tests showed. Tilapia and pollock were popular substitutes, the report said. Dover sole was discovered to be Asian “sutchi catfish” or common sole, and white tuna was often actually escolar, a snake mackerel with known diarrheal effects. The fish has been banned in some countries.

Sushi restaurants had the highest incidence of mislabeling in L.A., the study found. Oceana reported that 87% of the samples of 10 types of fish it took from 21 sushi eateries were not correctly identified.

All of the red snapper sushi sampled was mislabeled. Half of it was tilapia. Eighty-nine percent of the white tuna sampled at sushi restaurants turned out to be escolar.

Samples of yellowtail sold at sushi restaurants were often Japanese amberjack. Flounder was frequently sold as halibut, and sea bream was substituted for sea bass.
As someone who loves sushi and seafood more broadly, this is distressing. Sea bass is perhaps my favorite fish entrees, while I usually have yellowtail and other tuna when I eat sashimi.

This does seem like technology will allow us to solve a problem of economic fraud — minor as it may be.