Over the Rainbow

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Not long ago, an elderly neighbor strolled by as I was cutting away the English ivy strangling a Douglas fir in my front yard near Seattle. “Hooray for you!” she cheered. “Kill that ivy.”

Her huzzah reflected a common tenet among environmentalists today. Native species (Doug fir) are good, exotics (ivy) are bad. So much time, effort, and money are spent controlling and eradicating invasive species—it cost the federal government $1.2 billion last year—that it’s hard to imagine anyone arguing for the introduction of non-native species.

“An elegant and engaging natural history of the rainbow trout.”

And yet that’s exactly what an earlier generation of naturalists did. Proponents of the “acclimatization” movement in the late nineteenth century disseminated exotic plants and animals to the far corners of the world, in the name of improving nature’s design. In the United States, house sparrows were imported to control pests. The seeds of today’s starling infestation were planted in 1890 when a Shakespeare fanatic, determined to see all the species mentioned in the Bard’s plays roaming North America, released a flock of 60 birds in New York’s Central Park. But if success among species is measured by worldwide dissemination, the champion of the acclimatization movement was surely the rainbow trout.

As Anders Halverson recounts in An Entirely Synthetic Fish, an elegant and engaging natural history of the rainbow trout, Oncorhynchus mykiss began the 1870s as an obscure native of coastal rivers along the Pacific Rim. By the 1970s, it lived in all 50 states and more than 80 countries on every continent except Antarctica. “The range expansion that corn, sheep, dogs, and humans only achieved over thousands of years,” Halverson writes, “rainbow trout have accomplished in little more than a century.”

In the course of exploring how and why that happened, Halverson, a Colorado fly fisher who earned his PhD in aquatic ecology, has written one of the year’s most delightful works of nonfiction, a slim, quietly compelling volume that combines the leisurely literary style of an essayist with the tenacious curiosity of an investigative reporter. As a study of the weird ways in which human desire interacts with the wild world to produce evolutionary winners and losers, An Entirely Synthetic Fish deserves a place on the shelf alongside Mark Kurlansky’sCod and Jared Diamond’s Guns, Germs, and Steel.

So how did the rainbow trout become the most commonly cultured trout in the world? One word: sportfishing.

During the post–Civil War leisure boom, baseball emerged as America’s working-class sport and fly-fishing as the wealthy man’s pursuit. Vanderbilt, Morgan, and Carnegie filled their creels at the South Side Sportsmen’s Club, a private fishing enclave on Long Island. The sport was driven at least partly by ruling-class fear of racial lassitude. Well-to-do men—white men—feared that success and wealth were generating a class of pasty, soft-muscled urbanites, doomed to be overthrown by the virile hordes of ethnic immigrants pouring onto the nation’s shores. Outdoor camping became fashionable. “But to really reconnect with their virility,” Halverson writes, “men needed to capture and kill.”

“Trout fishing became nearly as industrialized as chicken farming.”

The rapid industrialization that bestowed wealth upon the South Side Sportsmen, however, also spoiled their fishing streams. The native brook trout of America’s eastern streams went belly-up in warmer, more polluted waterways. Species tough enough to survive—like the catfish, an ugly scavenger (and favored food of slaves in the old South)—were too low-class. “What these men really needed was a quarry that was both hardy and game and preferably had some claim to aristocracy,” writes Halverson. “What they needed was another trout.”

What they found was the rainbow. In the spring of 1875, members of the California Acclimatizing Society put a boxload of 500 rainbow trout eggs on a train bound for New York. These rainbows, native to northern California’s cool clean mountain streams, proved adaptable to the east’s warmer polluted streams. To sportsmen they were prized prey—quick to rise to a fly, strong fighters, and delicious on a dinner plate. Members of the New York Fish Commission vowed to spread them far and wide and “give to the private trout breeder and sporting angler exactly the fish he wants.”

Over the next hundred years, trout fishing in America became nearly as industrialized as chicken farming. State hatcheries raised millions of fish and planted them in lakes and streams—sometimes dropping them from the air—where they were snapped up by eager anglers. The difference between wild trout and stocked rainbows may have been philosophically troubling to some purists, but to most sportsmen it made no difference. When you’re helping your child catch a trout, you just want the kid to hook one, and the fresher the stock, the better the chances.

“Efforts to stop stocking are recent, but the results are heartening.”

The cycle remained unbroken until the 1970s, when researchers found that excessive trout stocking was actually killing wild trout. Not only did hatchery-raised fish spread a deadly parasitic pathogen, their aggressive feeding behavior sometimes devastated wild fish.

Efforts to stop stocking are recent, but the results are heartening. Montana, which pulled back on its stocking program in the 1990s, now boasts world-famous wild trout streams that attract $500 million in fishing tourism every year. In California, state fisheries workers spend their days pulling rainbow trout out of the alpine lakes into which they were airdropped a generation ago. Now that rainbows are no longer eating the tadpoles, native frogs are returning.

If my neighbor were to hike in California’s Sierra Nevada range, she might well offer the state fisheries workers a cheer along the lines of the one she gave me:Hooray for you! Kill those rainbows. The lessons learned over the past 50 years have clearly taken hold among American environmentalists. One hopes they will travel quickly around the world. As Halverson notes at the end of the book, “China is today undergoing an industrial revolution that in many ways mirrors the United States of the nineteenth century.” And one of the fastest-growing pursuits around China’s major cities is fishing for hatchery trout.