Room For Debate tackles over-fishing. Here's Taras Grescoe, author of Bottomfeeder: How to Eat Ethically in a World of Vanishing Seafood:

In 1988, we hit peak fish, with the worldwide catch (adjusted for Chinese over-reporting and the fluctuating Peruvian anchoveta fishery) topping out at 78 million tonnes (about 86 million U.S. tons). Species after species have crashed, from cod in the Atlantic to bluefin tuna in the Mediterranean. Gourmet trends have spelled doom for such formerly obscure species as Chilean sea bass, monkfish and orange roughy. Even pollock, the fish in the Filet-o-Fish sandwich, is now being overfished. Almost half the fish on our plates is now a product of aquaculture and many farmed species, including shrimp and salmon, are fattened with the ground-up bodies of smaller, but perfectly edible species.
So here is the principle that now guides my fish-eating: I graze at the middle and bottom of the oceanic food chain. Instead of tunafish salad tuna is a top-level predator I fill my sandwiches with mackerel, sardines or herring. These are the small schooling fish, still relatively abundant in the oceans, that we now grind up to make fertilizer or cat food, and they have become mainstays of my diet. I eat all the mussels, farmed abalone, lobsters and oysters I can: these bottom-dwellers actually clean the oceans. For a special treat, I’ll have a bigger fish like trout or wild-caught salmon from British Columbia or Alaska (when I can afford it, and when the runs are in good shape). I consult guides like the Monterey Bay Aquarium’s seafoodwatch.org to keep up to date on the state of the stocks.

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