Sharks may not be the only victims when humans consume shark fin soup, according to a study published in a recent issue of the journal Marine Drugs.
In the study, Kiyo Mondo and coauthors discovered that shark fins contained high concentrations of neurotoxins linked to neurodegenerative diseases in humans including Alzheimer's and Lou Gehrig Disease (ALS), posing a significant health risk to consumers of shark fin soup and cartilage pills.
The authors sampled seven species of sharks from the waters of South Florida: Blacknose (Carcharhinus acronotus), Blacktip (Carcharhinus limbatus), Bonnethead (Sphyrna tiburo), Bull (Carcharhinus leucas), Great hammerhead (Sphyrna mokarran), Lemon (Negaprion brevirostris) and Nurse (Ginglymostoma cirratum) sharks, detecting high levels of the neurotoxin -N-methylamino-L-alanine (BMAA) in fin samples taken from the sharks.
BMAA is produced by free-living cyanobacteria, and its presence in sharks is a result of bioaccumulation up the marine food web to apex predators. Previous studies have shown that patients dying with diagnoses of Alzheimer's Disease and ALS had unusually high levels of BMAA in their brains (compared to almost none those without the diseases), and the levels found in shark fins overlapped the levels measured in the brains of Alzheimer's and ALS victims.
The authors hope that their study might help reduce demand for shark fin soup and shark products, thereby aiding in their conservation.
For more information, see the paper: Mondo, K, N Hammerschlag, M Basile, J Pablo, SA Banack and DC Mash (2012) Cyanobacterial neurotoxin -N-methylamino-L-alanine (BMAA) in shark fins. Marine Drugs 10, pp. 509–520.
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