A Partner Effort for Fishery Management and Monitoring in the Glen Canyon Reach

The National Park Service, in cooperation with our Arizona Game and Fish Department partners, manages the 15.5 mile (25 km) long Glen Canyon Reach below Glen Canyon Dam as a Recreational Rainbow Trout Fishery.

A Group Effort

The US Geological Survey’s Grand Canyon Monitoring and Research Center (GCMRC) and the Arizona Game and Fish Department have been conducting monitoring and research on the rainbow trout population in the Glen Canyon Reach for many years. The Bureau of Reclamation and NPS work closely with these partners who perform many of these studies with funding allocated through the Glen Canyon Dam Adaptive Management Program.

The partners in this effort have 3 primary goals for the fisheries program in the Glen Canyon Reach:

1. To maintain a high quality, recreational rainbow trout fishery from Glen Canyon Dam down to the mouth of the Paria River;
2. To conduct annual monitoring to ensure that nonnative predatory fish like brown trout, walleye, and smallmouth bass do not begin to reproduce or become established; and
3. To continue to conserve and enhance the populations of endangered native fish in Grand Canyon down to Lake Mead.

All of the partners agree that the recent increase in brown trout is a significant concern and that this species of fish is undesirable in the Glen Canyon Reach and should be controlled. They also agree that the efforts to control them should also continue in key areas in the Grand Canyon.

A Focus on Brown Trout

With brown trout reproducing and increasing in numbers upstream of Lees Ferry since 2014, they present a concern in this location for several reasons:

• Brown trout are predators that feed on rainbow trout, spawn in many of the same areas as rainbow trout, and threaten the overall quality of the recreational rainbow trout fishery.
• Brown trout are migratory in their native habitats in Europe and they even do well in murky waters similar to those found in the Colorado River when the Paria River is discharging large volumes of sediment.
• Brown trout can spawn and survive in warmer river waters than rainbow trout, conditions that may occur as Lake Powell fluctuates up and down more during the lengthy droughts that have been occurring recently.
• Should these predators migrate downriver they pose a significant threat to endangered humpback chub in the Grand Canyon.

The NPS, in cooperation with their partners are preparing to launch an Incentivized Harvest program that will make payments to anglers who focus on and remove brown trout from the Glen Canyon Reach. By targeting and removing large numbers of subadult and adult brown trout the goal of this program is to maintain, and, over time, reduce the overall population of brown trout in the Glen Canyon Reach. The specifics for this program will soon be announced during the year 2020.

Focused removal of brown trout by anglers is expected to help maintain the recreational rainbow trout fishery in the Glen Canyon Reach, as well as ensure that the NPS and partners do not have to use mechanical harvesting or other tools that may disrupt the rainbow trout fishery. These efforts may also reduce the likelihood that large numbers of brown trout migrate downriver and threaten endangered fish in Grand Canyon. Monitoring will continue throughout the implementation of the Incentivized Harvest program to analyze the efficiency and efficacy of this management tool.