This is not to say that all aquaculture is bad. China alone accounts for an estimated 70 percent of the world’s aquaculture  where it is small in scale, focuses on herbivorous fish and is not only sustainable but environmentally sound. “Throughout Asia, there are hundreds of thousands of small farmers making a living by farming fish,” said Barry Costa-Pierce, professor of fisheries at University of Rhode Island.

But industrial fish farming is a different story. The industry spends an estimated $1 billion a year on veterinary products; degrades the land (shrimp farming destroys mangroves, for example, a key protector from typhoons); pollutes local waters (according to a recent report by the Worldwatch Institute, a salmon farm with 200,000 fish releases nutrients and fecal matter roughly equivalent to as many as 60,000 people); and imperils wild populations that come in contact with farmed salmon.

Not to mention that its products generally don’t taste so good, at least compared to the wild stuff. Farm-raised tilapia, with the best feed-to-flesh conversion ratio of any animal, is less desirable to many consumers, myself included, than that nearly perfectly blank canvas called tofu. It seems unlikely that farm-raised striped bass will ever taste remotely like its fierce, graceful progenitor, or that anyone who’s had fresh Alaskan sockeye can take farmed salmon seriously.

If industrial aquaculture continues to grow, said Carl Safina, the president of Blue Ocean Institute, a conservation group, “this wondrously varied component of our diet will go the way of land animals  get simplified, all look the same and generally become quite boring.”

Why bother with farm-raised salmon and its relatives? If the world’s wealthier fish-eaters began to appreciate wild sardines, anchovies, herring and the like, we would be less inclined to feed them to salmon raised in fish farms. And we’d be helping restock the seas with larger species.

Which, surprisingly, is possible. As Mr. Safina noted, “The ocean has an incredible amount of productive capacity, and we could quite easily and simply stay within it by limiting fishing to what it can produce.”

This sounds almost too good to be true, but with monitoring systems that reduce bycatch by as much as 60 percent and regulations providing fishermen with a stake in protecting the wild resource, it is happening. One regulatory scheme, known as “catch shares,” allows fishermen to own shares in a fishery  that is, the right to catch a certain percentage of a scientifically determined sustainable harvest. Fishermen can buy or sell shares, but the number of fish caught in a given year is fixed.