When the Water Hits the Road: The Return of the Westslope Cutthroat

Catching trout with a bit of bent wire is a rather trivial business, but fortunately people fish better than they know. In most cases it is the man who is caught.

—John Muir

Why do we try to save endangered species? It is a question we no longer answer or even ask, since we regard the matter as settled: a species gets scarce enough, the US Fish and Wildlife Service issues a finding and the professionals swing into action, like firefighters, or a hospital trauma team. If the question does come up, it is answered easily by utilitarian claims, like the classic cure-for-cancer argument ("The biosphere is a pharmacopeia filled with treasures…"). It reduces all of life to the level of a lab rat, but it, and similar claims, serve the purpose of defending the Endangered Species Act from the regular assaults it faces.

But the professionals who do the swinging into action have a different experience. The lucky person who holds the endangered species in the hand, or gets close enough to have the creature notice and maybe threaten attack, with a look drilled right into the eye—these people know that there are other reasons. They don't talk about them because they want to be taken seriously as scientists, and not sound loopy. Even among themselves they don't say much because the motive that drives them is beyond words anyway. I know, because I got to inhabit their world when I went chasing after an impossibly rare fish in Yellowstone National Park.

That fish was the westslope cutthroat trout. It is not "endangered," at least not yet, but it is headed that way. The fish was once abundant. Of the fourteen native American cutthroat subspecies, it was once the most plentiful and widely distributed. Among other places, it could be found all along the west side of Yellowstone National Park. It has been reduced to a fraction of its former range; in the upper Missouri river drainage that fraction is five percent. In Yellowstone the westslope cutthroat has either been eliminated or hybridized to the point that it no longer is what it was. The villains in the story are not the usual ones (overfishing and habitat destruction)—the fish are doing poorly, after all, in the world's first national park, an intensely regulated landscape. The problem is that many of Yellowstone's fish are nonnatives that have outcompeted the native fish nearly everywhere in the park. Don't blame the National Park Service; the serious fish stocking, carried out by true believers with the deep self-confidence of the insane, commenced decades before the Park Service even existed. Native Yellowstone cutthroat have also been moved into nonnative waters. Along with other, even more thoroughly nonnative trout, they have interbred with the westslope cutthroat. The problem is thus more subtle than fish floating belly-up. The westslope cutthroat is in danger of having its genome ruinously diluted, while fish that look similar to the real thing are alive and healthy.

So the species appeared to be sunk. However, in the middle of the last decade a genetically pure population turned up in the distant northern corner of Yellowstone National Park, in what used to be an unnamed tributary of Grayling Creek, Last Chance Creek. But it was not the last chance: in that same year, another genetically pure population was discovered in two small watercourses named Oxbow Creek and Geode Creek. Both had been empty of game fish when the park first became a park, and both were located far from the westslope cutthroat's usual home. The fish got into this odd place when Geode Creek was stocked in 1922 with what the hatchery people recorded only as "cutthroat trout." I picture Jim Earl driving the hatchery tanker to the place he'd been told to drive it, dumping the fish, and never giving it a second thought. It was just another load of fish. The westslopes were forgotten.

Once the genetically pure populations turned up, the federal machinery chugged into action, as documented...