What are contaminants?

Despite their valuable qualities, fish can pose considerable health risks when contaminated with substances such as metals (e.g., mercury and lead), industrial chemicals (e.g., PCBs) and pesticides (e.g., DDT and dieldrin). Through increased testing, many of our oceans, lakes and rivers are now known to be surprisingly tainted. As a result, some fish are sufficiently contaminated that Environmental Defense recommends limited or no consumption.
 
Where do contaminants come from?

Contaminants enter the water in a variety of ways. Industrial and municipal discharges, agricultural practices, and storm water runoff can all deposit harmful substances directly into the water. Rain can also wash chemicals from the land or air into streams and rivers. These contaminants are then carried downstream into lakes, reservoirs and estuaries.

Fish take in these substances in several ways, and their contaminant levels depend on factors like species, size, age and location. Mercury, for example, is naturally converted by bacteria into methylmercury. Fish absorb methylmercury mostly from their food, but also from the water as it passes over their gills. Generally, larger and older fish have had more time to bioaccumulate mercury from their food and the water than smaller and younger fish. In addition, large predatory fish (like sharks and swordfish) near the top of marine food chains are more likely to have high levels of mercury than fish lower in marine food chains due to the process of biomagnification.

Fish can also absorb organic chemicals (such as PCBs, dioxins and DDT) from the water, suspended sediments, and their food. In contaminated areas, bottom-dwelling fish are especially likely to have high levels of such toxins because these substances run off the land and settle to the bottom. These organic chemicals then concentrate in the skin, organs and other fatty tissues of fish. Wild striped bass, bluefish, American eel, and seatrout tend to be high in PCBs, since they are bottom-tending fish often found in contaminated rivers and estuaries.

The above was sourced from www.oceansalive.org

We always think of fish as clean and healthy alternative in our diet. I can remember about 5 years ago a well known fish supplier in New York's Fulton market was caught selling stripped bass from the Hudson River. This bass made it into some of Manhattans finest restaurants. As we know the Hudson River has faced years of chemical buildup. Not one person I know would even consider eating bass from the Hudson River. Although Shad is said to be edible from the Hudson River because supposedly it does not eat and absorb toxins during it river journey.

So is the seafood we are eating considered clean and pure? There are lots of fish that just come from the wrong areas of the world or are farmed in such a manner that increases these chemical exposures. Farmed salmon for instance has large amounts of dioxins and other harmful chemicals. These farmed salmon eat fish pellets that are made from other fish and fish parts. If these fish come from contaminated waters then it will carry down in the food supply. So the farmed salmon will bio-concentrate these dioxins, mercury and other impurities. When lots of fish are forced into small farms the risks of disease increases. This is when the use of antibiotics are increased. Because these farms are profit driven the use of growth enhancers such as synthetic hormones are given.

Where should are fish come from?

Certain areas of the world are much better off than other areas. I always like Alaska for good clean seafood. Alaska has very strict population management and is out of reach from large populated areas. I also just discovered a small company based out of Tobago, just off of Trinidad. This small company delivers hand line caught fish to several New York restaurants. Fish of this quality usually never goes to supermarkets. Supermarkets are very sensitive to price. These high quality fish most likely end up in high quality restaurants. Chefs seem to pay more for the fancy ingredients. As a general rule the fish I buy from wholesalers cost more than at the local supermarkets. There are many area around the world that supply bountiful seafood from clean waters.

What to do can we all do?

The questions you should ask are, how was this fish caught and where was it caught. There are great Internet companies that will overnight you extremely fresh fish. Also health food stores usually have a good selection on sustainable seafood in the freezer section.

As I said last month, you have ever right to know where and how the fish was caught you are eating.

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