Toxic Fish

When I taught Environmental Health at NHC Institute in Montreal in the mid-90s, I used a comic postcard to show how toxins concentrate in animal proteins.

In the first panel were little fish, each with a toxic symbol in its belly indicating a low-level of toxicity. When a bigger fish ate a few small fish, all their toxic symbols showed up in its body. When it was eaten by a yet bigger fish, all those toxic symbols were passed on. Finally a man eating a fish dinner exploded from the concentrated toxins in one piece of fish.

The oceans have become even more dangerous since I taught that course. In addition to man-made pollutants, the warming of the oceans is causing tropical toxins to move north and infect new fish.

There was a story in the New York Times Magazine recently about a man who got ciguatera poisoning from eating barracuda in the Caribbean. An organism growing on tropical reef algae produces a toxin. As in the cartoon I showed my class, this fat-stored toxin grows more concentrated as it moves up the food chain from the algae-eating fish to the predators like shark and barracuda. When humans eat the big fish, they get ciguatera poisoning, a non-lethal but debilitating illness that can take months to recover from.

As a vegetarian, I am like the little fish who eats low down on the food chain. I probably have the equivalent of one toxic symbol in my body -- not as many as the man whose head exploded.

If you eat seafood, stick to the smaller fish, not the large predators.

And consider the consequences of your food choices on the health of the oceans. Seafood Watch, run by the Monterey Bay Aquarium, explains which fish are sustainable and safe to eat, and describes fishing practices and fish migration routes. There's an iPhone app so you can carry the info to the store or restaurant with you.

Their Super Green list names ocean-friendly fish with low levels of mercury contamination and high levels of omega 3s.

When you consume fish, eat lots of liver-supporting greens, and take a moment to thank the oceans for providing you nourishment despite the devastating impact of humans.