Trophy Fish–And A Chain of Species Destruction at Yellowstone

Stocked fish are often home-wreckers for native species

by Richard Conniff/The New York Times

Recreational fishing is a pastime in which people have come to expect the fish they want in the places they happen to want them. That is, they want their fish stocked and ready to catch, even in places those fish never originally lived. This practice can seem harmless, or even beneficial. But the introduction of one “beneficial” species in Yellowstone National Park suggests how rejiggering the natural world for human convenience can cause ecological disaster for almost everything else.

All it took at Yellowstone Lake, the 136-square-mile centerpiece of the park, was the introduction of lake trout, a fish originally found mainly in the Northeast and Canada and beloved by anglers everywhere. The federal government had transplanted them to smaller lakes within the park in the 1890s, a time when adding fish to remote fishless lakes seemed like a smart way to spread around America’s amazing abundance. But a century later, in 1994, the introduced species turned up in Yellowstone Lake, which was already celebrated for its own native Yellowstone cutthroat trout. Park managers theorized that an angler illegally introduced the fish, either by accident or in the misguided belief that it would improve a big lake with plenty of potential for further sportfishing. One result is that anglers now catch 20,000 lake trout a year there.

But the lake trout went on to gorge on the young of the cutthroat trout, and the population of the native subspecies