Three Simple Rules for Fish Eaters

They’re not what you think

It’s been over a decade now since the writer Michael Pollan advised: “Eat food. Not too much. Mostly plants.” Ever since, a certain kind of progressive supermarket aisle has emerged: “Real” foods, calorie-limited portions and vegetarianism (or at least Meatless Mondays) have become culinary aspirations for millennials and boomers alike.

Mr. Pollan’s advice is sound. But what about the 71 percent of the Earth’s surface that provides humans with 350 billion pounds of food every year? How do you make rules for our oceans and freshwater ecosystems, whose vast production is, even in this increasingly mechanized world, still more than half wild?

The top three seafoods on Western plates are shrimp, tuna and salmon, together more than half of what we eat from the sea. Each is largely imported, and each comes with significant complications.

Since I first read Mr. Pollan’s haiku-like dictum, I have been trying to be like Mike — i.e., to work out a seafood three-liner that would be as concise, elegant and free from exceptions as his. I can’t say that I have been entirely successful. No sooner do I present a draft idea at a local seafood forum than…