By John Martin

When it comes to mercury content, not all fish are the same.

New Yorkers have access to every food imaginable. From the most exclusive restaurants to the hundreds of food carts scattered throughout the city, there is something here for every palate and every budget.

With this much variety, it’s sometimes easy to forget that some of our favorite foods can contain hidden risks. For instance, although fish can be a source of high-quality protein, omega-3 fatty acids and many vitamins and minerals, some species of fish can also contain harmful elements, like PCBs and mercury.

The EPA recently released the results of the agency’s New York City Commercial Market Seafood Study, which examined mercury concentrations in the most commonly consumed seafood in New York. Although the amount of mercury normally found in fish is not a health concern for most, the risk can be high for those eating certain kinds of fish and for unborn babies and young children. For instance, high levels of mercury can harm a young child’s developing nervous system.

During the study, EPA scientists purchased samples of 33 seafood species from vendors at the Fulton Fish Market in the Bronx, which supplies most of the fresh seafood sold to restaurants and stores in the New York area. After extensive testing of the collected samples, the species found to have the highest mercury concentrations were tuna, swordfish, Spanish mackerel, and mahi-mahi. Shellfish tended to have the lowest overall concentrations.

The entire NYC Commercial Market Seafood Study, including findings on all the fish species EPA tested, can be found here.

Although many people eat high-mercury seafood, the good news is that people are consuming less of it. Another recent EPA study has found that blood mercury levels in women of childbearing age dropped 34 percent from a survey conducted in 1999-2000 to follow-up surveys conducted from 2001 to 2010. Additionally, the percentage of women of childbearing age with blood mercury levels above the EPA’s level of concern decreased 65 percent from the 1999-2000 survey and the follow-up surveys from 2001-2010. A likely reason for these decreases was that women had shifted from eating higher-mercury types of fish to lower-mercury types of fish.

The lesson here? If you like fish, keep eating fish– just make sure you educate yourself and choose your fish wisely.