Of Frogs and Fish
Trout are eating tadpoles in high mountain lakes -- and that may change the way we look at stocking.
The buzz in biological circles could make a backcountry lake angler croak.
Researchers have compiled mountains of data that show introductions of nonnative trout are annihilating native amphibians in high-elevation waters. That evidence, coupled with the clout of the Endangered Species Act, leaves little doubt the curtain is falling on a century-old era.
Well-intentioned rangers, wardens, and anglers once used mules to pack milk containers filled with trout fry into thousands of fishless wilderness lakes. Modern managers use aircraft to continue the tradition. But in the zeal to create and sustain the continent’s remote fishing holes, it turns out they have gone too far.
“Endangered species concerns for amphibians could be a good thing for fishermen by forcing changes in the way high lakes are managed,” says Roland Knapp, a University of California at Santa Barbara researcher. Should anglers be outraged? Should we rise in protest over the recent petition to list the mountain yellow-legged frog as a threatened species? Should we fight for the status quo in mountain lakes?
“No,” say scientists and anglers who have studied the issue.
Knapp’s survey of 2,200 high lakes and ponds in California’s Sierra Nevada Mountains jibes with studies in Idaho’s River of No Return Wilderness, where trout are crippling local populations of spotted frogs and long-toed salamanders. Similar results have surfaced from amphibian research in Washington’s North Cascades National Park and the High Uintas of Utah, as well as far-flung sites in South America and Spain.
Yet these frogs hopping toward the brink of extinction are heralding changes that could improve the backcountry catch.
Wilderness fisheries were established with no scientific basis or regard for connsequences. As early as the 1930s, however, some biologists were starting to wonder. High-country fish stocking was eliminated in Yellowstone National Park in 1954 out of concern for the impact on native fauna. By 1980, stocking had ceased in most national parks, yet objections amounted to a murmur — because the fishing didn’t disappear.
“About 80 percent of the Kings Canyon National Park lakes where trout had been introduced continue to have fisheries similar to what they had before stocking was stopped in 1977,” Knapp says. “That tells me there was a whole lot of stocking going on across the country that wasn’t necessary.”
Annual stocking of fish in nutrient-poor mountain lakes where introduced fish are naturally reproducing is a recipe for skinny trout with big heads. “The quality of fishing in many lakes would improve if stocking were stopped,” Knapp believes.
With extremists calling for an end to all fish stocking, it may be time to consider Knapp’s reasonable proposal: Fisheries agencies in states with backcountry stocking programs must be encouraged to coordinate basin-by-basin research that would identify which lakes are best suited for natural fauna and which are best for stocking.