During one of his many visits to the Northwest Territories, Barry Lopez, author of Arctic Dreams, was asked by a native elder how long he intended to stay. Before Lopez could respond, the elder, who’d met a journalist or two in his day, grinned and answered his own question. “One day: newspaper story. Two days: magazine story. Five days: book.”

The point was a shrewd one: There is a timeworn tradition of writers traveling to the Canadian Arctic and Alaska to marvel at the land—at its nightless summers, its eccentric inhabitants, its fearsome bears. Jack London spent less than a year in the Klondike. John McPhee based Coming Into the Country on four trips from his home in New Jersey. The fascination of the North stems, in part, from the fact that it’s a damn hard place to visit, much less live in; little wonder that much of its literature is penned by outsiders.

You’re allowed, therefore, some initial skepticism of Kings of the Yukon, whose author, Adam Weymouth, lives, the jacket tells us, “on a Dutch barge in London.” Kings—one part travelogue, one part ethnography, and 10 parts ode to a charismatic fish—recounts a 2,000-mile canoe trip down the Yukon River, from ice-strewn headwaters to sprawling delta. Weymouth’s journey runs countercurrent to the upriver migration of the Yukon’s king salmon: “many pounds of muscle, toned through years of swimming headlong into Pacific storms, and their flesh … red as blood.” These mighty fish give Kings its title and focus—and help its author find, remarkably, something new and insightful to say about the North.

Weymouth’s Yukon fixation began in 2013, a year when just 37,000 king salmon returned to the Yukon—scarcely 10 percent of the historical average. The previous year, 23 Yup’ik fishermen had been arrested for flouting a state fishing ban, a deliberate act of civil disobedience. At their trial, which Weymouth covered for The Atlantic, the defendants noted salmon’s centrality to Yup’ik religion and argued that the First Amendment protected their right to fish. The judge, though sympathetic, slapped each fisherman with a $250 fine.

When Weymouth returns to investigate further in 2016, he finds a culture in slow collapse, fading with its most important resource. Fishing is permitted again, but it’s hardly worth it. Young people have decamped for Alaska and Fairbanks; fish-drying sheds stand derelict. Inside one abandoned cabin, “threadbare curtains blow in the breeze from shattered windows. … The clock is stopped at twenty past four, the calendar stopped at August 2011.”

Although Weymouth explores the science behind the decline’s possible causes—Is it overfishing? Ocean conditions? Climate change?—he is most concerned about its human victims. As he drifts from Dawson City to Emmonak, he meets a parade of Native and white fishermen, whose stories he tells with delicacy and dry humor. There’s Isky, a rapping descendant of Pueblo Indians who wants to make fishing cool for local kids again; Richard, who sardonically narrates bus tours for discomfited New Zealanders; Jim, a caviar-plant operator who goes by Egg Man. Especially memorable is Mary Demientieff, a gregarious Athabascan elder with “family the length of the river, the breadth of the state.” Mary presides over a flagging fish camp, where in the evenings she plays the guitar with “glee, unselfconsciously … laughing and wheezing,” a scene so charming it almost dispels the sadness.

Inevitably, Kings of the Yukon revives some familiar Alaskan tropes: Practically every writer who’s ever encountered a grizzly—including, admittedly, me—has meditated on feeling “conflicted between fear and the privilege of the moment.” (Your anxiety and awe are probably heightened when you come from a country whose largest carnivore is the badger.) Mostly, though, Weymouth’s nature writing is exquisite, even when he’s evoking the unlovely end of a salmon’s cycle: “Its kype is caught in a rictus somewhere between a snarl and a leer, and its gills are clouded with fungus, where it gasps for air as though breathing through cotton wool.” Just as Weymouth acclimates to the rhythms of his voyage, one of Kings’ joys is stretching out in its prose, stately and pleasurable as a flat stretch of river.

While fishing communities have waned, Weymouth finds that another culture has ascended to take their place: reality TV. Half the riverside dwellers he meets, it seems, feature in one of Alaska’s myriad unscripted dramas, from Andy of Life Below Zero to Stan from Yukon Men. “It seems quite possible,” Weymouth writes, “that Alaska has the highest ratio of television celebrities in the world.” Forget salmon—the biggest drivers of Yukon commerce today are National Geographic and the Discovery Channel. If we don’t reverse salmon’s collapse, reality stars might someday be the Yukon’s last kings.

Ben Goldfarb is a frequent contributor to High Country News, where this review first appeared.

Kings of the Yukon

By Adam Weymouth

Little, Brown and Company

288 pages, $27