Biomagnification: The Role of Sharks in Sustaining the Sea’s Toxic Balance

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Twitter was all a-twitter (groan!) the other day when this photo turned up of a great white trailing after a man in a single person kayak in Cape Cod. (Huffington Post)

Sharks are more awesome than some people give them credit for, and I don’t mean as soup.

Despite the fact that sharks don’t kill as many people as Jaws would have you believe, people kill thousands of sharks each year; primarily through targeted hunting (mostly for fin soup) or inadvertently catching them when longline fishing.

“Worldwide commercial fisheries discard and estimated 38.5 million tonnes of marine life, accounting for over 40% of the estimated total marine catch (DAVIES RWD, et al. Defining and estimating global marine fisheries bycatch. Marine Policy (2009)” –

Even more disturbing than lazy, loose work practices and complete lack of ethical regulation on industries that affect life, the United States Humane Society reports ‘Shark Kill Tournaments’ occurring regularly on both coasts, where people are inhumanely and aggressively hunting and killing sharks for prizes, cash and bragging rights.

“One third of all pelagic sharks are threatened with extinction, and half of the shark species targeted by commercial fisheries are threatened. Many shark populations have declined dramatically over the past thirty years, some by as much as 99%.” –

Why Sharks Are Important

Sharks, alive and in the ocean as they should be, fulfill an important step in an important process called biomagnification, wherein toxic substances become increasingly more concentrated and plentiful as they move up the food chain from one organism to another. When ‘persistent’ toxins like mercury, PCBs, heavy metals, and arsenic enter the ocean environments (via our pollutants) they lodge themselves into the fat of creatures and don’t biodegrade, toxifying the creatures themselves and increasingly so with each step up the food chain. As apex predators, sharks control the health of a number of populations of marine species by going after the old, sick and toxic (and inadvertently keeping them out of our food supply).

“Where sharks are eliminated, the marine ecosystem loses its balance.”  —

Visit SharkWater today to help save this crucial species from extinction.

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