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Is it OK to eat sharks?

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A scallop farm in Japan, part of the new wave of aquaculture that may help save many marine species.

By Blaise Jones

Sharks have been harvested and eaten all over the world throughout human history. Many cultures rely heavily on fishing as a way of life, shark fishing included.

Sharks have been hunted traditionally in Africa for centuries, and the practice still continues to this day. In South Pacific countries such as Fiji shark fishing has always been practiced, though studies have shown sharks are only harvested directly, and most bycatch (69.6%) is released. There are records of shark harvests in the United Kingdom dating back to the 1500s. Italy and France have long histories of diets including shark meat, and Spain is actually the No. 1 exporter of shark meat in the world.

Asia is the most notorious region for shark fisheries in the world come from Asia, specifically China. Shark fin soup started out as a rare meal for Chinese emperors and has since evolved into a luxury food favored by the wealthy and influential in Hong Kong and throughout China. As the middle class of China has grown, so too has the demand for this “delicacy.”

One international Chinese star has worked to reverse the dietary trend. NBA star Yao Ming condemned the dish in publicized advertisements. Many influential Chinese chefs have switched to imitation shark fin made of mung bean. Though their efforts are helpful, it may be too little too late considering that the global population of some shark species have been depleted by as much as 99 percent due to the shark fin industry.

Gummy shark.

Meaty Mercury

While traditionally shark meat is a nutritious meal high in protein, modern markets have seen a milestone in malignant mercury in the meat. Mercury is a byproduct of burning coal and ends up in water all over the world. Fish unintentionally absorb it through their gills, and the toxin builds up in their body systems. While the amount these fish absorb may not harm the individual animal, the mercury is transferred from prey to predator when these fish are eaten. When the predator eats more prey that contain mercury, the larger animal becomes contaminated, and that contaminated fish causes problems when it is either fished for by humans and consumed, or the contaminated fish is eaten by a larger fish, which is then caught and consumed by humans.

The process is known as bioamplification, or biomagnification, where concentrations of certain chemicals increase up the food chain. Predatory fish like sharks eat tons of fish in their lifetime to stay alive and many of these prey species contain mercury. As the shark eats more infected fish, the amount of mercury in their shark’s system increases.

Unfortunately, many of the victims of bioamplification are also animals humans like to eat. Bluefin tuna populations, the most popular tuna in the world, have been noted to have a 0.5 ppm (parts per million) concentration of mercury in their bodies. The shortfin mako populations, one of the most commonly harvested sharks for its meat, has been found with concentrations of mercury as high as 1.8 ppm. More than 0.3 ppm of mercury is unsafe for human consumption.

Mercury poisoning damages the brain, heart, kidneys, lungs, and immune system. Unborn and young children are especially vulnerable. Mercury poisoning causes damage to their developing nervous system, severely limiting their intelligence and ability to learn. High mercury concentrations in the human body can lead to mental degradation and eventual madness. The term “mad as a hatter” refers to mercury poisoning. Mercury was used in the tanning industry prior to the 20th century and individuals who made hats – hatters – had to wear hats nonstop as part of their business. After years of wearing hats of pelts laced with mercury, the chemicals would alter the personality of the hatter to the point where the hatter eventually was considered mentally deficient, or “mad,” thus becoming “mad as a hatter.”

Sustainable Shark Fisheries?

Though vulnerability to overfishing, sharks can be sustainably harvested. With careful management and responsible practices, many species of sharks are commercially viable. However, this is much easier said than done.

While most species are unsuitable for sustainable fisheries due to a slew of reproductive restrictions, studies have come up with four potential candidates for sustainable fisheries: the gummy shark, the Atlantic sharpnose, the bonnethead hammerhead, and the blue shark. Each of the four species averages between 7-30 pups at each birthing (with some having as many as 135 pups). Individuals reach maturity in as little as four years, and can breed every 8-12 months.

Sustainable fish farms and aquaculture benefit from technological advancements that occur all the time so hopefully today’s inventions will improve tomorrow’s sustainable shark populations.

SOURCES:

  1. “Sharks: The Animal Answer Guide” by Gene Helfman and George H. Burgess
  2. “The Encyclopedia of Sharks” by Steve Parker
  3. http://www.flmnh.ufl.edu/fish/isaf/home
  4. http://www.flmnh.ufl.edu/fish/isaf/worldwide-summary/
  5. http://www.sharktrust.org/en/shark_fisheries
  6. http://content.time.com/time/magazine/article/0,9171,2021071,00.html
  7. http://www.fao.org/docrep/005/x3690e/x3690e03.htm#bm03
  8. http://www.nature.com/articles/srep17556
  9. http://www.sciencedirect.com/science/article/pii/S0165783606002153
  10. http://www.wildaid.org/sharks
  11. http://mercurypolicy.scripts.mit.edu/blog/?p=499
  12. http://www.sharks.org/blogs/science-blog/toxic-sharks
  13. https://www.nrdc.org/stories/mercury-guide
  14. http://www.medicinenet.com/mercury_poisoning/article.htm
  15. http://www.publish.csiro.au/mf/MF98017
  16. http://www.fishbase.org/summary/5943
  17. https://www.flmnh.ufl.edu/fish/discover/species-profiles/rhizoprionodon-terraenovae
  18. https://www.flmnh.ufl.edu/fish/discover/species-profiles/sphyrna-tiburo
  19. http://www.fishbase.org/summary/898
  20. http://www.iucnredlist.org/details/39381/1

-TSF-

#sharks #food #culinary #TSF

 
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