If you listen to the experts, you should be cutting out meat and adding more seafood to your diet.

For example: The American Heart Association recommends “eating fish (particularly fatty fish) at least two times a week,” presumably to obtain the omega-3 fish oils linked to cardiovascular health.

The American Dietetic Association suggests consumers “Include a variety of seafood more often in place of some meat and poultry.” For older adults, ADA recommends that they “Vary your protein choices. Eat a variety of foods from the protein food group each week, such as seafood, nuts, and beans and peas.”

The Centers for Disease Control and Prevention urges Americans to “Choose a variety of lean meats and poultry, seafood, beans and peas, eggs, processed soy products.”

Harvard School of Public Health, the self-styled “authority” on all things nutritional, urges its followers to eat lots of fish and seafood because they are “major sources of omega-3 fatty acids and healthful nutrients, such as vitamin D and selenium.” In fact, HSPH states that “eating approximately one to two 3-ounce servings of fatty fish a week—salmon, herring, mackerel, anchovies or sardines—reduces the risk of dying from heart disease by 36%.”

Even the hardcore Center for Science in the Public Interest—which eventually finds fault with pretty much every food category for one reason or another—has spent years banging the drum about mercury contamination of seafood (solution: more regulatory oversight, including mandatory recalls and point-of-sale warning labels on fish). That cautionary stance is not something to dismiss, but in between the “Mercury can kill you!” warnings, even CSPI manages to squeeze in a plea for adding “healthy, wild seafood” to one’s everyday diet. “Experts estimate that [eating wild salmon] could save 300 lives for every one death from cancer caused by the contaminants in salmon.”

Yikes. I’m no expert on actuarial statistics, but I guess that’s an acceptable tradeoff.

Last of the forage fish

However, the larger problem with the “eat more seafood instead of meat and poultry” mandate, the one hardly anyone talks about, is this: Every bite you take out of a seafood product takes a bigger bite out of the environment.

That’s not my opinion, that’s the conclusion of a host of scientists who have been tracking the world’s deteriorating fisheries for decades. Part of the problem—obviously—is overfishing in unregulated waters, where giant factory trawlers literally vacuum up the ocean from seabed to surface, decimating target species such as tuna and cod. On top of that, widespread pollution, particularly in the estuarine ecosystems that support so much of the marine food chain, is wreaking havoc with seafood harvests.

Here’s a lengthier explanation of that last phenomenon from the Earth Policy Institute, a left-leaning environmental group but one that sticks to sound science in its policy recommendations:

“The fish near the bottom of the aquatic food chain are often overlooked, but they are vital to healthy oceans and estuaries,” according to a recent report titled, Overfishing Threatens Critical Link in the Food Chain. “Collectively known as forage fish, these species—including sardines, anchovies, herring and krill—feed on plankton and become food themselves for larger fish, seabirds and marine mammals. As demand for animal protein has soared over the last half-century, more and more forage fish have been caught to feed livestock and farmed fish instead of being eaten by people directly. A growing body of scientific evidence suggests that current fishing levels are dangerously high—both for the forage fish themselves and for the predators and industries that depend on them.”

Not so sure about the feeding fish to livestock evidence—not in North America, anyway—but the rest rings true.

According to institute estimates, forage fish typically account for one-third of the 80 million tons of fish caught annually in the world’s oceans, with over 90% of that tonnage processed into fish oil (sold as nutritional supplements) and dried fishmeal, used extensively in aquaculture and fish farming.

Know what the largest U.S. fishery (by weight) is today? Atlantic menhaden, a forage fish that is processed for the above-mentioned products, as well as animal feed and fertilizer.

Know what the largest fishery in the world is? Peruvian anchovies—the world’s largest source of fishmeal, annually exceeding 10 million tons harvested by some 1,200 boats, processed in 140 factories and producing fishmeal and fish oil worth about $2 billion a year in exports.

How long that kind of harvesting will remain sustainable is unknown, and long-term climate disruptions will certainly not help.

Here’s the bottom line: For all the health benefits of seafood—and they’re legitimate—and despite the claims of seafood proponents that “properly managed,” the world’s forage fisheries could remain sustainable, if Americans alone took seriously the advice of the nutrition gurus, we’d wipe out the world’s ocean fisheries in a matter of months.

It’s questionable to push people away from red meat and poultry on the basis of the alleged superiority of seafood.

It’s practically criminal to do so in the face of potential ecosystem damage that, unlike dietary deficiencies, might be next-to-impossible to reverse.

The opinions expressed in this commentary are solely those of Dan Murphy, a veteran food-industry journalist and commentator.