Declining Amphibians Sound Alarm

The buzz in biological circles is enough to make a mountain lake angler croak.

Scientists fishing for answers about the decline of amphibians in the high country aren’t casting fishing rods, and they’re not practicing catch-and-release.

They’re packing gillnets and talking fish eradication.

Researchers have compiled mountains of data that show introductions of non-native trout are annihilating native frogs and salamanders in high-elevation waters.

The evidence, coupled with the clout of the Endangered Species Act, leaves little doubt the curtain is falling on an era that began more than a century ago.

Well-intentioned rangers, wardens and anglers once used mules to pack milk containers filled with trout fry into tens of thousands of fishless wilderness lakes.

Modern managers use planes and helicopters to continue the tradition.

But in their zeal to create and sustain the continent’s most remote fishing holes, they apparently have gone too far.

“Endangered species listing for amphibians could be a good thing for fishermen as well as for frogs by forcing changes in the way high lakes are managed,” said Roland Knapp, a researcher from the University of California at Santa Barbara.

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 to the death for our mountain fisheries?

“No,” say scientists and anglers who have looked closely at the issue.

The frogs hopping their way toward extinction are heralding changes that could improve rather than curtail wilderness fishing.

Backcountry management strategies were established without scientific basis, said Curtis Milliron, who manages eastern Sierra fisheries for the California Fish and Game Department. “The mission was simply fish distribution with no thought to the consequences,” he said. “You couldn’t start anything like that now.”

In other words, the fish stockers didn’t know what they were doing.

Starting in the 1930s, however, some scientists were starting to wonder. Yellowstone National Park eliminated fish stocking in 1954 out of concern for the impact on native fauna that had evolved without fish.

“But most of Yellowstone was a natural trout Mecca,” said John Varley, the park’s chief biologist. “With so many waters naturally stuffed with trout, the end of stocking in mountain lakes passed with only a murmur.”

Trout stocking in the high country of Glacier National Park ended in 1971, and most other national parks stopped the practice before 1980.

The fish have disappeared from some of those park waters, while fishing remains excellent in others.

Here’s why.

Knapp and his crews spent five years surveying 2,200 lakes and ponds in two adjoining areas with different fish-stocking histories: the John Muir Wilderness, where fish stocking continues, and the adjoining Kings Canyon National Park, where stocking was phased out starting in 1977.

Knapp was not particularly surprised that his research found lakes with frog populations were five times more common in the park than in the wilderness.

The research in California’s Sierra Nevada Range jibes with studies in Idaho’s River of No Return Wilderness, where trout have been found to cripple populations of spotted frogs and long-toed salamanders.

Similar results have surfaced from ongoing research in Washington’s North Cascades National Park and the Unita Mountains of Utah, as well as studies in South America and Spain.

“Trout have the same negative effect on amphibians in these high systems wherever you go,” Knapp said.

The big surprise in Knapp’s research was that 80 percent of the lakes in Kings Canyon Park that were stocked before 1977 still have a fishery similar to what they had before stocking was stopped.

“That tells me there was a whole lot of stocking going on - as well as a whole lot of controversy - that wasn’t necessary,” he said. “I believe at least 65 percent of the fisheries currently being stocked in the Sierra Nevada are self-sustaining, but no one realized this, so they just kept stocking more fish year after year.”

Ironically, fish managers have long known high mountain lakes to be relatively sterile waters that don’t grow much food.

“Putting too many fish in a high lake is one of the worst things you can do,” said Milliron. “The more fish you have, the smaller they will be. The fewer fish, the larger they will be. It’s about that simple.”

With petitions rolling in to list amphibians as endangered, it’s time to listen to Knapp, Milliron and others who have a reasonable plan.

Support basin-by-basin research that would identify which lakes are best suited for natural fauna and which are best suited to trout fishing.

In some cases, fish will need to be removed. Research indicates that gillnetting can be effective in doing this without use of chemicals, at least in some smaller waters.

Knapp’s research indicates that about 20 percent of the high Sierra lakes would be suitable for fish eradication by gillnetting. Of that 20 percent, managers could factor other considerations, such as their popularity for fishing, trail access, and their productivity for trout.

In the final analysis, some of those lakes would be appropriate to manage specifically for amphibians and other native fauna.

“We have a lot of wiggle room, Knapp said. “The Sierra Nevadas alone have about 8,000 lakes and ponds, and we’re talking about removing fish from only a small percentage of them.”

Anglers and sport fish managers can maintain control by taking the lead.

Reel in the fish stocking program and give a few waters back to the frogs.

“The worst thing fishermen can do is think this issue will go away,” Knapp said.