Is there any stopping these trout?

Oncorhynchus mykiss—the species of fish you and I know as rainbow trout—first appeared about three million years ago, after splitting from the genus that gave us salmon to form its own family. Originally native to an area of the Pacific Rim that stretches from Mexico to Alaska and parts of eastern Russia, the rainbows spread north and south along the Pacific coast starting around 10,000 years ago. That, basically, is what nature had in mind for the rainbows. But as ecologist Anders Halverson explains in a new book, for nearly 150 years the fish has been the protagonist in an entirely different history, one of man’s most convoluted nature-renovation projects.

In An Entirely Synthetic Fish: How Rainbow Trout Beguiled America and Overran the World, Halverson is concerned with the oddly symbiotic relationship between Americans and rainbows, a connection that stretches back to 1865, and the end of the American Civil War. After the war, many Americans (men, of course) took to fishing. Why? Halverson offers a few possible explanations, two of which seem most plausible: America’s biggest cities, in the second half of the 19th century, were cesspools of pollution and disease, the result of a massive uptick in urban living. Fishing was a good excuse to escape your dirty neighbourhood. And fishing represents virility—a quality white Americans sought to bolster in the face of massive African-American immigration from the South to the North after the Civil War. Northern aristocrats “feared that success and wealth generated an effete ruling class that would easily and inevitably be overrun by the uncivilized hordes.”

In any case, these new sport fishers needed a sparring partner—a fish tough enough to put up a fight (but not too tough that it would actually win the battle against man and reel), and yield a tasty reward. Enter the rainbow trout. In the hierarchy of fish, catfish, at home in sluggish, muddy waters, were at the low end; salmon, “having the advantage of being the royal fish of England,” were chi-chi. But rainbows, “the aristocrat buccaneer of big waters,” were the most popular catch for the late-19th-century fishing man. And, with a dash of lemon and some butter, it made a great dinner, too.

As the rainbow’s popularity soared, though, a logistical problem arose: nature only intended for the fish to live in certain locales, but anglers across America wanted in on the action. Fortunately, science had recently discovered the solution: artificial spawning. Fish hatcheries had sprung up, and in northern California, rainbow trout were being plucked out of rivers and lakes—workers were stripping females of their eggs and fertilizing them with a spray of sperm from the males. The eggs could then be shipped to just about anywhere—by pack mule or rail, and, later, simply by dropping them from airplanes. By the end of the 19th century, the U.S. Fish Commission had sent rainbows to 33 of 38 states in the Union, and to England, Germany, France and Canada.

Today, America’s waters are teeming with rainbow trout. According to Halverson, “For every one of the four million Americans born each year, state and federal hatcheries hatch, raise and stock approximately 20 rainbows into the country’s public waters.” Another 60 million pounds are raised in private hatcheries across the country every year.

But with more rainbows came more problems. The unnatural environment of the hatchery was the ideal setting for scientists to master the unnatural work of genetic manipulation. There are now at least 75 strains of rainbow trout—some are faster and some are slower, some are fighters and some less rambunctious. Different strains vary in colour, size and even shape. This does not sit well with many anglers, who complain that the altered rainbows now dominating the water don’t taste particularly good; “wild” trout have acquired a certain fisherman’s mystique, but they’re hard to find—their mutant cousins typically outhustle them in the evolutionary battle for food.

The term “synthetic fish” is something of a misnomer—there are, in fact, “real” rainbow trout out there, even if they are becoming harder and harder to find. But if the book’s title over-sensationalizes the truth about rainbows, it hints at the truly bizarre history of a fish that represents the struggles, fears and changes inherent to America and Americans over the last 150 years. And that’s worth chewing over the next time you throw a handsome rainbow on the grill.