Mercury in Your Fish

Mercury in Fish
Graphic by: Colly Smith ’16

For as long as I can remember, going out to Sushi has been a Finger family affair.

We always order an array of raw fish, of which we attempt to split equally, although that never really happens.

It was not until I was older that I started to notice my parents conversing with sushi chefs about ‘mercury’ each time we went out.

High mercury levels in fish being sold for consumption is a problem plaguing millions of seafood habitués.

Although mercury naturally occurs in most fish, its levels have started to increase dangerously due to rapid industrialization. Mercury bioaccumulates, meaning it builds up in the blood streams of the organisms that consume it, and therefore is the most pertinent in fish at the top of the aquatic food chain that live longer and are larger.

Highly sought after tunas, such as Bigeye, Bluefin, and Yellowfish, contain more mercury than fish lower on the food chain such as, shrimp, salmon, and catfish. The United States Environmental Protection Agency warns “not [to] eat Shark, Swordfish, King Mackerel, or Tilefish because they contain high levels of mercury.”

Not only does mercury bioaccumulate in fish, but it also bioaccumulates in the bodies of those who consume it. Therefore, it can build up in human’s bloodstreams overtime.

Mercury, can however, leave the body. Your body naturally removes mercury over time, but significant consumption of mercury in a short period of time will lead to accumulation of it in your bloodstream.

Excess consumption of fish containing high concentration of mercury can produce negative consequences.

Dr. Jane Hightower of the Natural Resources Defense Council explains the harmful effects of mercury poisoning on individuals who regularly consume fish.

“Low-level mercury poisoning has been found to cause memory loss, hair loss, fatigue, depression, difficulty concentrating, tremors and headaches. Because it is hard for the body to eliminate, it can build up and may affect the nervous system. It is not known how many people might be affected by methylmercury, and while [I] could not measure how much of their suffering was directly related to the over-consumption of fish, the symptoms stopped when fish was eliminated from their diet.”

What makes this issue even more confounding is that according to the data promulgated by the U.S. Food and Drug Administration mercury levels vary greatly among specific species of fish. Big Eye Tuna, at their lowest readings have a  low and relatively safe .128 ppm (parts per million) while the maximum reported levels in a particular Big Eye fish were a dangerous 1.816 ppm, an astonishing 1500 percent differential. Where and how a fish is caught plays a significant difference in predicting mercury level concentrations.

Some fish are usually safe to eat wherever they come from. Salmon, which is over 90 percent farmed, and Red Snapper, a relatively small and short lived fish, are two high quality fish that are generally pretty low on the mercury charts.

Richard Maxwell, head of the dining hall at Thacher, assuaged fears about mercury in Thacher’s fish supply.

We get our fish from a company out of LA – American Fish & Seafood. This is the preferred supplier of Bon Appetit in our area. We try our very best to adhere to the seafood recommendations set by the Monterey Bay Aquarium Seafood Watch a program for sustainable fisheries. We purchase only “best choice” or “good alternative” according to their guidelines. Dealing with one company that understands our goal makes it much easier to get the right products that support sustainable fisheries. We serve different kinds of fish – quite often it is Mahi Mahi or Icelandic Cod. This week we bought Black Cod (sable fish) and Northern (Alaskan) Halibut”.

Thacher students don’t have to give up eating fish and all their heart healthy benefits.

Just become an educated consumer before anything goes into your mouth, and make sure to ask the right questions.

To become better informed, consult the The Monterrey Bay Aquarium. The organization has charts that can guide consumers to pick safer alternatives when picking the next seafood meal.

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