Series: ARCHEOLOGY IN YELLOWSTONE: Yellowstone Science 26-1

Archeology of Yellowstone: A Day in the Field, Collaboration is Key to Upper Gibbon Fishery Restoration

Collaborating biologists prepare for the application of rotenone at Grebe Lake in September 2017. More than 75,000 pounds of chemical, boats, equipment, and supplies were transported to this backcountry site by helicopter to complete the project.
Collaborating biologists prepare for the application of rotenone at Grebe Lake in September 2017. More than 75,000 pounds of chemical, boats, equipment, and supplies were transported to this backcountry site by helicopter to complete the project.

NPS Photo - T. Koel

Collaboration is Key to Upper Gibbon Fishery Restoration
by Erik Oberg

In September 2017, a collection of 35 biologists and ecologists, interns, and park volunteers from several parks, agencies, and non-governmental organizations (NGOs) gathered at a series of lakes in the upper Gibbon watershed of Yellowstone National Park (YNP). The task at hand was to implement an ambitious project. The project area included 16 km (10 mi) of the Upper Gibbon River and Grebe, Ice, and Wolf lakes, totaling over 92 ha (228 surface acres). The challenge involved moving 75,000 pounds of supplies and equipment into the backcountry. The goal of this fisheries project was to protect and restore native westslope cutthroat trout and fluvial (river dwelling) grayling to the upper Gibbon watershed. The process included treating these waters with the piscicide (fish poison) rotenone to kill every adfluvial (lake dwelling) arctic grayling and non-native rainbow trout, deactivate the chemical, and then introduce native fish to the watershed. No small task.

The project site has an interesting history. As was common practice in the early days of park management, lakes, even fishless ones such as Grebe, Ice, and Wolf, were often stocked with non-native fish to provide recreational angling. Little was known about the long-term consequences of stocking. The first stocking of Grebe Lake occurred in 1921 with “one million fry from the State Fish Hatchery in Anaconda, Montana. Anaconda got its eggs from Georgetown Lake, and the Georgetown Lake population originated from spawning runs out of the Madison River near Ennis, Montana, about the turn of the century” (Varley and Schullery 1983). In 1932, a small hatchery and employee quarters were built near Grebe Lake to facilitate trapping and egg hatching efforts (Agency Report 1937). Today, old road grades, eroded dam structures, and foundations testify to these early efforts.

From the 1880s to 1930s, fishless lakes were stocked with non-native rainbow trout, grayling, and other species from outside the park. The descendants of these fish are now being removed in the upper Gibbon for the introduction of native westslope cutthroat and river-adapted grayling. It may seem counterintuitive to stock historically fishless lakes, even with native species; but these higher elevation waters are hoped to provide refuge for these species as water temperatures rise and other threats, such as water borne diseases, encroach on the park. Park managers are uncertain about how fish populations will adapt or adjust to climate change pressures. This project may provide the park with an important management tool for ensuring the long-term survival of fish that are native to the park, even if not native to this particular portion of the watershed.

Parks around the country face similar climate change questions. Will Joshua trees, giant sequoias, and redwoods still grow within the boundaries of the parks? Will they survive at all? Park managers in Yellowstone decided to experiment with a project like this and give native fish a potential toehold at higher elevations rather than risk a catastrophic fish die-off, like the one that occurred outside the park in the Yellowstone River in 2016, which may have been related to warmer waters and low flows. It may be better to make this investment now than try to explain why we didn’t do anything after it was too late.

The upper Gibbon River and aforementioned lakes have a long history of supporting fish populations. They are isolated from other watersheds, at higher elevations than many current fish populations, and are relatively easy to access. Park managers decided it was worth the effort to relocate these two native species to this area to buffer the effects of potential future climate warming.

A project this size dwarfed even the substantial staffing levels of the YNP fisheries program. They were going to need some help. Enter the collaborators. One of these collaborators came from a park over a thousand miles away and was an old friend. I’ve known Danny Boiano, Aquatic Biologist at Sequoia-Kings Canyon National Parks, for over fifteen years. We worked together at Sequoia, and I was immediately impressed with his knowledge and dedication. Danny has been working since 2002 to save the endangered mountain yellow-legged frog (Rana muscosa) from extinction. If you hike in the Sierras 30 years from now and are serenaded to sleep by a chorus of these frogs, it will be because of Danny Boiano. He recently wrote an environmental impact statement (EIS) to remove non-native trout from alpine lakes that are the last remaining habitat for these vanishing amphibians. Danny has been removing trout with nets for many years and making some progress. Piscicide treatments are the only way to effectively remove all trout over an area big enough to give frogs a fighting chance at survival. Danny came to Yellowstone for two weeks to work on this project, to see how managers plan and execute a large treatment project involving lakes and tributaries, and to learn the detoxification process.

The method for removing one or more aquatic species and introducing others is now fairly standardized: 1) isolate the project area, 2) completely remove target species, and 3) introduce native species. The process sounds simple; but the sheer size, timeline, and complexity of the project watershed made collaboration critical to success.

My role in this massive undertaking was small. Danny and I were assigned to follow a Grebe Lake tributary to its source, map it, and conduct a dye trace to chart its flow rate. This involved crawling over jack-strawed lodgepole pine trunks for several hours. We brought the data to project leader Jeff Arnold, who then calculated how much rotenone would be used for the drip station, set up to apply a steady stream of chemical to remove fish from one end of the stream to the other. For help with the miles of tiny tributaries, with flows too slow to treat with drip stations, Yellowstone benefited from an experienced practicioner. Ashley Rawhouser, Aquatic Ecologist at North Cascades National Park, has been working on smaller fisheries projects like this for 12 years. He led another team treating tributaries with backpack sprayers and checking the sentinel stations where fish are set in portable cages to ensure the treatment is working. This work was comparable to the mapping and dye tracing, but with 30 pounds of piscicide on your back. I was glad to be wielding a camera.

The really heavy work was treating the lakes. This was accomplished by a combination of backpack spraying along the shore and a boat-based crew applying powdered rotenone into the water. Only trained staff with pressurized respirators could do this work. My job was to document Yellowstone’s first-time use of boats to apply piscicide at this scale—and to stay upwind. During the Wolf Lake treatment, we saw a late-season common loon. The activity caused it to depart, but it served as a reminder of an important project element. We were removing the fish food source it and other species such as ospreys depend on. To mitigate this concern the piscicide would be applied, detoxified with potassium permanganate, and then native fish introduced, all before the snow flies. These 45,000 native fish will provide breeding stock to continue to repopulate the area, as well as provide food for species such as the common loon come springtime.

The piscicide works quickly, and soon the surface is dotted with dead fish. They blow ashore and can quickly attract scavengers. In order to remove the dead fish, my fellow collaborators and I made hundreds of “scooping” trips. Imagine wading along the lake shore with a large fish net, scooping dead fish into buckets. We removed approximately 10,000 rainbow and grayling. These buckets of fish were loaded into boats, counted, cut to prevent floating, and returned to deep sections of the lake for nutrient cycling. Student Conservation Association interns, staff from Turner Enterprises, Inc., and returning volunteer Christine Mire all contributed to the effort. Volunteers signing up to scoop dead fish is a testament to the deep connection many people have to this place!

Perhaps the best part of the experience, at the end of a sun-up to sundown work day, was connecting with the other team members back at base camp. Swapping stories from the day’s adventures and sharing experiences from outside the park made for easy conversation around the campfire. I don’t often have the chance to work with so many co-workers, volunteers, and, of course, my old friend Danny.

Our understanding of ecology has evolved a great deal from the early days of building roads and hatcheries to stocking non-native species. We won’t know if this project will provide a climate-change resilient habitat for many years to come. But for today, the Gibbon River project demonstrates the deep well of support YNP enjoys for its conservation efforts, the large scale of the challenges we face, and how much we can accomplish through collaborative efforts.


Varley, J.D., and P. Schullery. 1983. Freshwater wilderness - Yellowstone fishes and their world. Yellowstone Association, Gardiner, Montana, USA.

Agency Report. 1937. Box N-116, Nature and Social Sciences, File “620-30 Buildings, Fish Hatcheries Part I, Jan 1, 1936 to Dec 31, 1939.” Letter from [Park Supt] Edmund B. Rogers to NPS Director, July 29, 1937. Washington, D.C., USA.

Last updated: September 6, 2018