Coming Up in Yellowstone Science
On the Rise: Native Fish Conservation in Yellowstone National Park
by Todd Koel
Following the recession of glaciers some 8,000-10,000 years ago, native fish began dispersing to the Yellowstone region. By the late 1800s, the waters of Yellowstone supported 12 species (or subspecies) of native fish, including Arctic grayling, mountain whitefish, and cutthroat trout. These native fish species provided food for both wildlife and human inhabitants. After the establishment of Yellowstone National Park in 1872, park inhabitants and visitors initially harvested fish for sustenance and survival in this wild, remote place. Early park superintendents noted the vast naturally fishless waters of the park, and asked the U.S. Fish Commission to stock them. The first nonnative fishes (fishes from outside the park) were planted in 1889-1890. So important were fisheries during this early period, this harvest-oriented, fish management program accounted for over 310 million fish being planted in Yellowstone by 1955. In addition, between 1903 and 1953, some 818 million eggs were stripped from Yellowstone trout and shipped to locations throughout the country.
Popular publications describing the quality and abundance of fishing in Yellowstone became prominent. While most hunting was curtailed by early park management, the commercial harvest of fish was allowed to provide food for the hotels until 1917, the year after the National Park Service was created. During these early years, sport fishing became an accepted use of resources, and the phenomenal sport fishing experience that the park provided rose in notoriety. Yellowstone's recognition as an angling mecca was born. Largely due to the activities in Yellowstone and the popularity of its fisheries, recreational angling became a long-term, accepted use of national parks throughout the country.
Although Yellowstone has—and continues to be—an angling mecca with pristine waters supporting an abundance of fish, significant threats to the long-term persistence of native fish have emerged. Nonnative, predatory lake trout and exotic whirling disease were introduced to the vast, seemingly secure Yellowstone Lake ecosystem, home to the largest remaining concentration of cutthroat trout. In the early 2000s the impacts of an expanding lake trout population and whirling disease coincided with that of drought, resulting in a precipitous decline in cutthroat trout. Cascading effects through the ecosystem were documented. Grizzly bears are now seldom seen on cutthroat trout spawning tributaries, and few ospreys prey on cutthroat trout near the lake's surface or nest in adjacent trees. As measured by the frequency with which Yellowstone cutthroat trout are caught, angler success on Yellowstone Lake is less than one-half of what it once was prior to the existence of lake trout.
Coinciding with the cutthroat trout decline in Yellowstone Lake were changes in another previous stronghold for this species in the park, the Lamar River. Rainbow trout, which were intentionally introduced by park managers in the early 1900s and propagated at the Trout Lake hatchery near lower Soda Butte Creek, historically remained concentrated in the Yellowstone River below the falls at Canyon and the lower Lamar River. In the early 2000s, however, anglers began reporting catches of rainbow trout upstream more frequently. As rainbow trout hybridize with cutthroat trout, their spread has raised concerns about the security of the cutthroat trout in the upper Lamar River system. Additionally, westslope cutthroat trout and fluvial Arctic grayling, native to the upper Madison and Gallatin drainages, were largely lost due to the historic stocking of nonnative fish in Yellowstone. Only a single, small aboriginal westslope cutthroat trout population remains, discovered in 2005 in aptly named Last Chance Creek, a tributary to Grayling Creek. No aboriginal fluvial Arctic grayling remain.
Yellowstone's native fish have underpinned natural food webs, had great local economic significance, provided unparalleled visitor experiences, and defined much of the park's 20th century historical context. To address recent and historical losses, and reverse declining trends in native fish populations and loss of ecosystem function, the National Park Service has sought to take actions that will ensure their recovery.
In the next issue of Yellowstone Science, significant accomplishments made in restoring native fish over the past decade will be described. In addition, research and development of methods to more efficiently control nonnative lake trout will be presented. The issue will include articles with a broader scope that describe the range-wide status of Yellowstone cutthroat trout and efforts to prevent the introduction of additional aquatic invasive species across the Greater Yellowstone Ecosystem. Of particular importance will be a description and recognition of the many partners who support and contribute to the Native Fish Conservation Program in Yellowstone, and research being undertaken to conserve Yellowstone's native fish through 2016, the National Park Service centennial year.