I highly recommend that you read Tuna's End by Paul Greenberg, in the New York Times Magazine. It is an excerpt from his forthcoming book, Four Fish: The Future of the Last Wild Food. The title alone is chilling. I will never eat tuna again; I had already cut way down because of the mercury content, but the idea that tuna might disappear is enough for me to boycott it entirely. I love sushi, but I love the life that gives it more.
We are killing our oceans with overfishing; climate change--we've actually managed to alter the chemistry of the ocean, killing corral reefs and other creatures; and pollution--oil being the least of it. I urge you to go online and learn about the Great Pacific Garbage Patch, a swirl of trash larger than the state of Texas (and that's the low estimate) trapped in a gyre. One grandmother in Concord, Massachusetts, Jean Hill, learned about it from her grandson, and promptly introduced and began advocating for a plastic water bottle ban in her town. The citizens voted in support of a ban, though it might be unenforceable. Right on--as we used to say, and hopefully will say again, and again, and again. We must demand of our leaders that they implement programs to clean up our planet.