For many, the Lenten season is now in full swing, prompting a whole host of Friday Fish Fries as faithful Christians forego eating meat on Fridays. With this in mind, it seemed appropriate to consider the state of the world's fisheries and provide a little insight into how to choose the fish that have been harvested with the least negative impact to the planet. Fish is, generally, a welcome addition to any diet, as it is low in fat, high in protein, contains a number of valuable vitamins and minerals, and is a primary source for omega-3 fatty acids, which may help prevent heart disease. Unfortunately, the impact of commercial fishing on oceanic populations may put a damper on eating this wide variety of healthy foods.

According to the United Nations Food and Agriculture Organization, more than 70% of the world's fish species have been either fully exploited or seriously depleted. In the north Atlantic, commercial fish populations of cod, hake, haddock, and flounder have fallen by as much as 95%. These statistics have led to the prediction that the populations of all species of wild seafood could be collapsed by 2048. Meanwhile, pollution in our lakes, rivers, and oceans has caused many fish populations to be host to dangerous levels of mercury, PCBs, and other chemicals.

Not only have our oceans been overfished, but ecosystems have also been damaged by fishing methods such as trawling. Millions of sea birds, turtles, and other aquatic life have been caught in nets as bycatch, while the bottoms of the oceans have been scraped by trawlers. Fish ponds where species are bred for consumption may help take the pressure off the oceans (indeed, one quarter of fish and one third of shrimp consumption is now from aquaculture farms), but are risky in their potential to pollute and in the danger that escaped farm fish might have on fragile nearby ecosystems. Not only that, but feeding large pond-raised fish with smaller wild fish sometimes defeats the purpose.

It is, of course, no easy task to find out how responsibly the particular fish on your plate was harvested, but it is possible to choose fish that have traveled shorter distances to arrive there (fish from the Great Lakes or North Atlantic before those from the Pacific, for example). Additionally, there are lists available showing which fish are likely to have high levels of mercury, which have been overfished, which are raised in destructive fishing environments, and which have high rates of bycatch. Some of the best and worst are listed below, and the whole list is available at http://www.thegreenguide.com/doc/93/bestfish.

Also, since it is often best to eat foods found close to home, keep in mind possible advisories for Great Lakes fish. A good summary of safe and unsafe fish in Ohio is available at http://web.epa.state.oh.us/dsw/fishadvisory/Eat%20Your%20Catch_1page.pdf. And if all of this has deterred you from going to that fish fry, consider trying walnuts, soybeans, or flaxseed oil for those omega-3 fatty acids.

Best Choices (not overfished, not farmed destructively, low levels of bycatch, no mercury):

Catfish (farmed)

Clams (farmed)

Crab

Crawfish

Herring

Rainbow trout (farmed)

Salmon

Sturgeon (farmed)

Tilapia (farmed)

Trout (farmed)

Worst Choices (some combination of mercury, destructive farming, bycatch, and overfishing):

Flounder (Atlantic)

Haddock

Monkfish

Orange Roughy

Scallops

Shark

Shrimp

Swordfish