Mountain-Prairie Region

 

 

FEATURE SERIES


U.S. FISH AND WILDLIFE SERVICE
134 UNION BOULEVARD
LAKEWOOD, COLORADO 80228

Vol. II, No. 3

 

3. Once-Maligned Native Fish on Road to Recovery

If a poll asked anglers "What is the largest native trout of the Pacific Northwest?," chances are few will give the correct answer: bull trout. Defined by its size and predatory ability, the bull trout is the heavyweight of the salmon family. The world- record bull trout caught in 1947 in Idaho weighed 32 pounds.

Bull trout ee few will give the correct answer: bull trout. Defined by its size and predatory ability, the bull trout is the heavyweight of the salmon family. The world- record bull trout caught in 1947 in Idaho weighed 32 pounds.

Bull trout evolved in the Columbia River system more than 10,000 years ago and developed a niche as large, long-lived predators. They evolved to migrate between feeding and growing areas in rivers and lakes and the headwater streams where spawning and rearing occur.

Adult bull trout can travel six months and migrate 150 miles upstream during spring spawning runs. During fall months, females dig nests and deposit up to 10,000 eggs each, which are fertilized by males and then buried under eight inches of gravel by females. Adults return downstream, leaving the eggs to incubate and hatch during winter.

One-inch fry emerge from the gravel about April. After living one to three years in the spawning stream, juvenile fish head downstream for a bigger home and more fish to eat during their "teenage" years. At a size of twenty inches or larger and an age of five or six years, the adults make their first spawning migration.

Juvenile bull trout resemble brook trout but lack the brook's brighter red spots with blue halos and the signature worm-like markings. Adult bulls are sleek fish, drab olive in color with lighter bellies and small pink spots. When spawning season arrives this appearance changes dramatically. Males assume brilliant colors, with flame-orange flanks and bellies, and striking black and red fins edged with white.

It would hardly seem a fish so large and regal could suffer from discrimination, but such is the history of the bull trout. Forced to compete in the minds and hearts of anglers with the glamour and lore of salmon and steelhead across much of its range, the bull trout was cast as a second-class citizen.

To further complicate the issue, bull trout were known to eat migrating juvenile salmon and steelhead on their trek to the ocean. With the antipredator mentality that dominated at the time, bull trout were put on "undesirable" lists with coyotes and wolves, and were persecuted across much of their range.

But this sentiment has shifted. With today's greater understanding about the need to preserve native species, people recognize bull trout as an important symbol of our nation's aquatic heritage, and are struggling to save the species. Though bull trout are still found in Washington, Oregon, Idaho and western Montana, their total numbers are a fraction of their historical levels.

Three major factors have led to the species' decline. First, their habitat has been altered by dams, diversions, reservoirs and spillways, making it difficult for the migratory fish to spawn.

A second threat is sedimentation -- mud -- and warming of the bull trout's clear coldwater stream habitat. Land use factors such as improper logging practices, road building and excessive grazing of streamside vegetation have all contributed to the sedimentation of rocky stream beds needed for spawning. The resulting altered habitat favors other species instead, such as brook trout.

Finally, in efforts to create more diverse fishing opportunities for anglers, wildlife managers stocked an array of non-native fish species. Native bull trout and cutthroat trout largely replaced by brook, brown, lake and rainbow trout, as well as other species. Intentions were good, but consequences of these introductions have been mostly detrimental to native aquatic species.

Aldo Leopold, the father of wildlife management, once said "the first principle of intelligent tinkering is to save all the parts." In recognition of the plight of bull trout, efforts are underway to save the species in places where their habitat is most intact.

In 1994, the U.S. Fish and Wildlife Service found that bull trout were "warranted for listing" under the Endangered Species Act. While the fish is not yet listed, the warranted finding underscores the multitude and complexity of threats the bull trout faces.

The Service is developing cooperative agreements with the U. S. Forest Service and other land managers that will reduce the impacts of land management activities on bull trout. Individual states are also developing restoration plans to evaluate problems and find local solutions.

Until potential solutions are proposed and implemented, it's too early to tell whether widespread success in bull trout restoration has been achieved. Aquatic biologists believe the bull trout is an indicator species whose successful restoration is critical to restoring ecosystem health. Thankfully, it is not too late to halt the decline for this important symbol of our aquatic heritage.


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