Keeping an Eye on Mountain Trout Lakes

Mountain Lake surveyEach summer, FWP fisheries workers head into the backcountry to monitor high-elevation fishing waters. By Bob Gibson

This story is featured in Montana Outdoors May–June 2009

While Montana’s trout rivers are famous worldwide, the state’s mountain trout lakes receive little notice in major sporting publications. That’s good news for anglers who have long enjoyed the more than 1,000 high-elevation lakes that support trout fisheries.

Recently, the department’s south-central region made it easier to locate the 340 trout lakes in the Abasaroka-Beartooth ranges and the Crazy Mountains. An annually updated version of the region’s guide to mountain lakes in the Absarokas, Beartooths, and Crazies has been on-line for several years. Since 2008, it has included GPS coordinates to help anglers pinpoint lake locations. In addition, the guide provides details on fish species in each lake, fish abundance, stocking schedules, nearest trailhead, and firewood and campsite availability, and includes observations from FWP fisheries staff managing the waters.

FWP has been keeping close tabs on south-central Montana mountain lakes for more than four decades. In 1967, fisheries biologist Pat Marcuson began taking meticulous notes on the lakes. Every year since, biologists and fisheries technicians have updated the information. Eventually they worked it into an ever-expanding electronic database, which has become the most complete and detailed record of mountain trout lakes in the country.

Marcuson, who is retired and now lives in Salmon, Idaho, says mountain lakes in the Beartooths received little attention from fisheries biologists before he began his surveys. Most information about fish populations came from game wardens who occasionally fished the lakes during backcountry patrols. Starting in the early 1960s, Marcuson says, people began hauling fish between mountain lakes in buckets to increase high-country fishing opportunities. Unfortunately, non-native brook trout often were dumped into lakes where they squeezed cutthroats and other native species out of historical habitat. The non-native fish problem was compounded when the state tried to plant fish in the lakes with airplanes. Pilots—many of them contracted—were unable to tell one lake from another and frequently dumped hatchery rainbow trout into lakes containing native cutthroats.

In 1967, officials with Montana Fish and Game, as the department was then known, decided it needed to do a better job managing mountain lakes. That summer, the department hired temporary employees to help Marcuson survey south-central Montana lakes. The crews carried 125-foot-long gill nets and a 100-pound inflatable boat into the wilderness and conducted fish surveys on 20 lakes. In later years, the surveyors became more efficient and were able to survey 50 or more lakes per summer.

When money got tight, the department eliminated the temporary positions. But Marcuson, committed to learning as much as possible about the mountain trout lakes, obtained funding from outside organizations, including the U.S. Forest Service. In exchange for USFS dollars, federal officials required that the surveys also include information about camping opportunities and the number of campfire rings at each lake. That information was added to Marcuson’s report and remains there today, even though backpacking stoves now are considered more environmentally friendly than campfires in wilderness areas.

The information was first available to the public when Falcon Press asked Marcuson to write a book about the best fishing spots in the Absaroka-Beartooths. Marcuson was concerned that the commercial book would list only the best fishing spots and endanger lakes by concentrating visitors in just a few places. To spread out fishing pressure, he convinced the publisher to produce a comprehensive guide that listed every lake. The result was Marcuson’s Fishing the Beartooths. The latest edition was printed in 1997 and is still available at many booksellers as well as at and other on-line sources.

Also on-line is FWP’s annual edition of Mountain Lakes Guide: Absaroka, Beartooth, and Crazy Mountains. This guide can be viewed on and downloaded from the FWP website (see sidebar) The department also has a limited number of printed editions at the regional FWP office in Billings. For information on mountain lakes in other parts of Montana, visit, click “Fishing” and then “Fish Stocking Info.”

Every summer, FWP biologists and technicians continue to cover hundreds of miles of rugged trails in the Absaroka-Beartooth ranges and the Crazy Mountains to update the guide and recommend planting schedules and management priorities. Every year for the past two decades, FWP biologist Mike Vaughn has updated the guide, while fisheries technician Earl Radonski has managed the backcountry surveys and helped analyze and publish the data.

Radonski says the lake fisheries in the Beartooths generally fall into two categories: self-sustaining and stocked. Self-sustaining lakes have enough spawning habitat to allow fish to restock themselves year after year. “These often contain so many fish that while fishing can be fast, the average size will be small,” Radonski says. “Average sizes and numbers of fish present change very little from year to year in most of these lakes.”

FWP regularly stocks lakes that have little or no spawning habitat. The department stocks an average of 100 Yellowstone cutthroat fingerlings per acre every eight years. “In the first few years after planting, anglers find many small fish,” says Radonski. “Then each year the fish will be larger but fewer in number.” After seven to nine years, the fish die of old age. “Anglers use the stocking history in our guide to predict what sizes and numbers of fish a given lake might currently contain,” he adds.Bear bullet

Bob Gibson manages the FWP Regional Information and Education Program in Billings.