Shark Fin Soup Comes With Side of Toxins

Shark fins drying in the sun.
Shark fins drying in the sun in Kaohsiung before processing. 30 percent of the world’s shark species are threatened or near threatened with extinction. (Image credit: Shawn Heinrichs for the Pew Environment Group)

The destruction of sharks for shark fin soup has helped put many wild species of the fish on the road to extinction. Now, new research suggests this costly meal may harm humans, too.

An analysis of shark fins from Florida waters found high concentrations of β-N-methylamino-L-alanine, or BMAA, a neurotoxin that has been linked to Alzheimer's and Lou Gehrig's disease. The find raises concerns that consuming shark meat and cartilage may put consumers at risk.

“The concentrations of BMAA in the samples are a cause for concern, not only in shark fin soup, but also in dietary supplements and other forms ingested by humans," study co-author Deborah Mash, who directs the University of Miami Brain Endowment Bank, said in a statement.

The researchers tested seven species of shark for the study: blacknose, blacktip, bonnethead, bull, great hammerhead, lemon and nurse sharks. The scientists clipped tiny fin samples off of living animals so as not to harm their subjects.

Reporting in the journal Marine Drugs, the authors found BMAA concentrations ranging from 144 to 1,838 nanograms per milligram. According to Mash, those levels are similar to the levels found in the brains of Alzheimer's and Lou Gehrig's disease patients.  Earlier research has linked the eating of BMAA-rich fruit bats in Guam with degenerative brain diseases, suggesting that consuming the toxin could affect human health.

The researchers hope the findings will help discourage the practice of shark-finning, in which as many as 70 million of sharks per year have their fins sliced off and are dumped back into the ocean to die.

"Not only does this work provide important information on one probable route of human exposure to BMAA, it may lead to a lowering of the demand for shark fin soup and consumption of shark products, which will aid ocean conservation efforts,” said study co-author Neil Hammerschlag, a University of Miami professor of marine affairs and policy.

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Stephanie Pappas
Live Science Contributor

Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.