That adage "fish is brain food" may be true, but that's a fisherman's tale when it comes to shark. A new study conducted by University of Miami scientists found high concentrations of BMAA in shark fins; this is a neurotoxin linked to degenerative brain diseases such as Lou Gehrig's, Alzheimer's and Parkinson's.
Sharks are among the most threatened marine species because they are killed primarily for their fins, which are used to make a Chinese soup that denotes wealth and power.
Shark fins are acquired from a process called finning, where the fin is cut off immediately after the shark is caught and the rest of the animal is thrown in the water to die.
The study draws a link between the consumption of shark fin soup--and dietary supplements such as cartilage pills--and significant health problems. Any shark fin is used to make the soup, but only seven species of shark caught in South Florida waters were tested in the study: blacknose, blacktip, bonnethead, bull, hammerhead, lemon and nurse sharks.
"The thing is very little has been done on BMAA because it is a new wave, a new understanding," says Neil Hammerschlag, co-author of the study. "We're only starting to understand the scope of the problem."
Hammerschlag says the concentrations of BMAA get higher up the food chain through a process called biomagnification. Hammerschlag
knew that BMAA was found in certain types of marine life and had a hunch
that sharks might contain the neurotoxin since they are an apex
predator.He worked with colleagues at the Miller School of Medicine to get an answer.
BMAA is found in cyanobacteria, a type of bacteria that obtains energy through photosynthesis; it's commonly found in the waters of South Florida and is eaten by other aquatic marine animals, which are in turn consumed by the sharks.
"Generally when you move higher up in the food chain you get higher levels of toxins," says Hammerschlag. "There are certain fishes in our area, including blue crab, that contain BMAA."
Considered the "food of emperors," shark fins are mostly eaten in China. Finning is illegal in several countries, including the United States, but remains unregulated in international waters.
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Most of the harvested shark fins are shipped to Hong Kong and China where there they are shipped worldwide.
Shark fins are a rare item in Chinese seafood markets in Miami, although some restaurants like the King Palace Chinese Bar-B-Q in North Miami Beach still sell it ($16.95 a bowl, with chicken or shrimp).
Hammerschlag hopes the study will curb the demand for shark fin soup. "I believe that people will hopefully alter what they're eating," he says. "As a result there will be less of a demand and less sharks will be killed."