Mountain Whitefish – Conserving Colorado’s Other Native Salmonid

For anglers in the know, these powerful fish and their voracious appetite can be the perfect solution when trout are stubborn or absent.
mountain whitefish
Mature whitefish gather for the October spawn in small tributary streams.

By Kevin B. Rogers

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Mountain whitefish and cutthroat trout are the only two salmonids native to the state of Colorado. Trout seem to get every angler’s attention, but whitefish deserve some respect as well. Despite readily taking a fly and providing exceptional fishing, whitefish have long been derided by anglers. Increasingly frequent drought conditions mean some anglers may never get a chance to enjoy landing Colorado’s other native salmonid, unless CPW and its partners take action. 

Some anglers confuse mountain whitefish with suckers due to their plain silvery coloration and down-turned mouths, while others dislike their inclination to hit heavily weighted nymph patterns instead of rising to dry flies as their trout cousins are prone to do. The fact remains, however, that mountain whitefish have saved many days on the water when trout were stubborn or absent. As with most things in life, we fail to appreciate them until they are gone.  

angler with mountain whitefish
Mountain whitefish are excellent quarry on a fly rod.

Native only to the White and Yampa rivers in Colorado, mountain whitefish are supremely adapted to the large Western rivers in which they evolved. They are sensitive to environmental changes and can serve as a canary in the coal mine when evaluating overall ecosystem health. They are highly migratory and require large, uninterrupted sections of river to complete their life cycle. 

Eggs hatch in early spring and the tiny fry ride the high, snowmelt-driven flows downstream to warmer waters where they grow rapidly. As they age, they work their way back upstream, invading headwater tributary streams to spawn each October. Historically, these migrations choked many small tributary streams, but the numbers of fish have dwindled in recent years, causing CPWs aquatic biologists some concern.

Declines can be attributed to a variety of factors including invasion of nonnative predators and parasites, but drought conditions appear to be the most harmful. With drought comes very low flows and unusually warm weather. The combination means water temperatures can rise quickly, often to dangerously high levels. The high temperatures reduce the amount of dissolved oxygen the water can hold, further stressing whitefish. Conditions like these decimated the mountain whitefish population in the Yampa River around Steamboat Springs during the drought of 2002.

Colorado’s burgeoning population growth and a warming climate makes fulfilling CPW’s mission to perpetuate the wildlife resources of the state that much more daunting. Fortunately, there is a litany of water and conservation partners that are also committed to preserving the integrity of Colorado’s rivers and streams. 

In the Yampa River, where whitefish declines have been particularly notable, the Colorado Water Trust, along with the Upper Yampa Water Conservancy District, Colorado Water Conservation Board, the city of Steamboat Springs, the Nature Conservancy, and a slew of additional partners have made it possible to implement innovative conservation measures considered impossible decades ago. 

In recent droughts, the Colorado Water Trust has purchased water stored in upstream reservoirs to add to the pool other water collaborators own, releasing them to increase flows, in turn benefitting the downstream ecosystem and its imperiled whitefish. The benefits have been unequivocal. 

The drought of 2002 devastated mountain whitefish in the upper Yampa, but these fish have been able to hang on through recent droughts in the last decade due to conservation partnerships involving a multitude of agencies, allowing them to rebound when normal water flows return. In a time when drought frequency is increasing, these sorts of partnerships become even more vital to the long-term survival of the underappreciated mountain whitefish. 

Learn more about CPW’s mountain whitefish conservation efforts on Colorado Parks and Wildlife website.

Video: Mountain Whitefish – Fly fishing is one of Coloradans’ favorite past times. No matter what time of year it is, there is always a chance to fly fish.
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Colorado Parks and Wildlife is celebrating its 125th Anniversary throughout 2022 to honor the legacy of our agency and the talented staff who make fulfilling CPW’s important mission possible. For more stories like this, please visit the Colorado Parks and Wildlife’s 125th Anniversary web page!

Written by Kevin Rogers. Kevin is and aquatic research scientist for Colorado Parks and Wildlife. Visit the Colorado Parks and Wildlife website to learn more about Kevin’s research projects.

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