Hatchery Fish Aren’t Universally Welcomed In Olympic National Park
Proposals to remove mountain goats in Olympic National Park have stirred so much controversy, few people are aware of lower profile efforts to eliminate trout.
Conservationists have backed a park proposal to exterminate the mountain goat because it’s a non-native species that’s endangering some of the native vegetation the park was established to protect.
Similarly, biologists want to lower the numbers of non-native fish in Olympic National Park alpine lakes to give the amphibians there a fighting chance at survival.
Amphibian populations are mysteriously declining worldwide.
Biologists believe one answer to the puzzle may be the eating habits of non-native fish such as the eastern brook trout, at least in the alpine lakes in the Olympics, North Cascades and Mount Rainier national parks.
Fisheries biologists last year descended on PJ Lake near Hurricane Ridge in Olympic National Park to study the size, abundance and eating habits of the brook trout. They want to determine the impact the prolific spawners have on larval salamanders and frogs.
The highest numbers of salamanders are found around lakes without fish, they say.
What biologists learn at PJ Lake, selected because of the numbers of fish there and its accessibility, could be applied elsewhere, said Rich Olson, a resource management specialist.
Eastern brook trout were planted in high country lakes in the 1920s and stocked in various waters for decades, said wildlife biologist Bruce Moorhead.
Rainbows, brook trout or cutthroats can be found in about 55 of the 300 lakes or ponds in Olympic National Park, said biologist John Meyers. But the fish stocking in the park’s waters ended early in the 1970s.
“The question we hope to answer is, ‘What total effect on the population did we have from year one?,”’ Olson said.
It may be possible to reduce the fish population to a level where fish and frog could coexist, Olson said. But the question is how many fish would have to go and how to do it.
Unfortunately, money to continue the study wasn’t granted, Meyers said.
Biologists gill-netted 500 brook trout out of PJ Lake last year roughly two-thirds of the population. But without funding, they have no way to tell whether removing the fish was a boon to amphibians.
On the other hand, lowering the fish population could result in larger fish. That might be a bonus for fishermen, but it also could be a negative for amphibians, since the larger fish might be more efficient predators.
But without funding, researchers won’t know for sure.
“This was your typical overpopulated, stunted brook trout population with fish in the 6- to 8-inch range,” Meyers said. The lake contained more fish than the food supply could support to larger sizes, he said.
But anglers don’t make a dent in the population, despite no restrictions on the size or number of fish that can be caught.
It doesn’t make sense to use rotenone, a common garden pesticide that has been used to kill fish in other parts of the country. The pesticide also could kill the amphibians and zooplankton, Meyers said.
“We’re not out to eliminate fish or fishing,” Meyers said. But alpine lake fishing has not been a priority in the park for 25 years.
Some park visitors have taken measures into their own hands. About four years ago, someone illegally stocked trout in Lake of the Angels, a lake with a low-density fish population at the headwaters of the Hamma Hamma River.
In addition to sucking up amphibian eggs, non-native fish create other problems, such as:
Fewer and less diverse native aquatic plants and animals. The fish eat everything they can find, including bottom plants, zooplankton, freshwater shrimp, insects, ants and beetles.
Harm to native bull trout, candidates for listing under the Endangered Species Act. Eastern brook trout are mating with bull trout at Crater Lake National Park in Oregon and have already being found in the upper Sol Duc River from the Seven Lakes Basin.
Shoreline damage as fishermen, hikers and campers walk through the fragile, wet meadows and streams around the edges of the high-country lakes.
Meanwhile, the opportunities to catch trout in the alpine areas of national parks seems to be slipping away.
Trout are still stocked in the low reservoirs and some high lakes of North Cascades National Park. But high lake stocking is limited.
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The following fields overflowed: BYLINE = Rich Landers Outdoors editor The Associated Press contributed to this story.