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 I get shouted down by a New England dragger captain whose cod doesn’t fill the bill.

But rules are useful no matter the exceptions. And since World Oceans Day was this month, I thought I would offer up my own, admittedly clunky, variation:

Eat seafood from countries with good fisheries management.

A much greater variety than we currently do.

Mostly farmed filter feeders.

Some explanations are in order.

To begin with, why start with the countries? Is there something intrinsically better about fish and shellfish caught in some waters over others? No. But there is something better about the way a handful of nations manage wild fish.

In a 2009 analysis in the journal Nature, which ranked nations by the level of compliance with the United Nations code of conduct for fisheries, only the United States, Norway…