Brown Trout Incentivized Harvest

Know Your Trout
Spotted fish with words: Brown trout spotted fish with red stripe and words: Rainbow trout
I'm a Brown Trout - catch as many of me as you can! Image - Iowa DNR
I'm a Rainbow Trout - throw me back for another day so I can thrive! Image - Iowa DNR
  1. Spots – Brown Trout often have red-orange spots with many spots having a blue-gray “halo”; spots are large. Rainbow Trout have numerous black spots lacking a “halo”, spots are typically small.

  2. Tail – Brown Trout have few or no spots on their tail; Rainbow Trout have distinct radiating spots on their tail.

  3. Body – Brown Trout have a brown-yellow body. Rainbow Trout have a olive-bluish back; adults typically have noticeable pink sides.




 

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Chart indicating rapid rise of brown trout population in Colorado River
Index of brown trout abundance (mean fish caught per minute of electrofishing) in Lees Ferry, 2001‐2016. The closed circles show the mean value; the whiskers show the 95‐percent confidence intervals.

AZGFD / David Rogowski

History of Fishing on the Colorado River Upstream of Lees Ferry


Before Glen Canyon Dam was built, the Colorado River flowed muddy and warm with great seasonal changes for eons and developed a community of native pikeminnows, suckers, and chubs with unique adaptations for utilizing that habitat. The hydrology and the physical and chemical makeup of the Colorado River completely changed when the dam was completed in 1963. The clear, cold water released from Glen Canyon Dam provided excellent conditions for a rainbow trout fishery. Hatchery raised rainbow trout were initially stocked in the 1960s thru the 1990s after dam completion. They eventually became a self-reproducing population. Arizona Game and Fish Department (AGFD) also experimentally stocked other trout and salmon species until it was determined that rainbow trout were best suited for the tailwater stretch of the river below the dam.

In 1981, AGFD designated the 15-mile stretch of the Colorado River below Glen Canyon Dam to Lees Ferry as a Blue Ribbon Rainbow Trout Fishery. Glen Canyon National Recreation Area manages the area as a high-valued recreational rainbow trout fishery.

Although stockings of brown trout below the dam were not self-sustaining and were eventually discontinued by AGFD in the mid-1980s, small populations of brown trout in Grand Canyon National Park that were stocked in the 1920s continued to reproduce and thrive in cold water tributaries of the Colorado River downstream. These brown trout populations spread out into the river and began to have a big impact on the endangered humpback chub population at the mouth of the Little Colorado River. In the early 2000s an extensive electrofishing effort was made by a host of agencies in order to reduce that particular brown trout population. Between 1984 and 2013, rainbow trout comprised about 97% of the fish population between the dam and the Paria River Riffle while brown trout only comprised about 2%. However, since 2014 brown trout have begun to successfully spawn and now make up over 10% of the fish population.

 

The Threat

The Colorado River below Glen Canyon Dam is home to native fish species like flannelmouth and blue suckers. Two endangered fish species, razorback sucker and humpback chub, can also be found in the Marble and Grand Canyon stretches of the river. Native fish are highly susceptible to predation by fish eating predators like brown trout. As brown trout grow, they begin to feed heavily on other fish species. As sub-adults and adults brown trout are 17-times more likely to eat other fish than are rainbow trout. The increase in number of brown trout in Glen Canyon has raised concerns for fish managers. As the Glen Canyon brown trout population grows, they could migrate downstream and pose an immediate threat to native fish species like the endangered humpback chub. Brown trout are also able to thrive in warmer river water than rainbow trout and are better adapted to hunting other fish in the murky river water of the Colorado River when the Paria River and side canyons are flowing.

 
Human hand holding fish by the tail in shallow water
Get these Brown Trout out of the Colorado River from Glen Canyon Dam to the Paria River Riffle. If they can't play nice with the endangered native fish, we aren't going to play nice with them.

Aristidis Harris

Why We Need Your Help


In 2019 the National Park Service completed a plan for non-native fish management from the dam to Lees Ferry and on through Grand Canyon National Park. We identified specific tools for managing non-native brown trout with much public and partner input.

Glen Canyon National Recreation Area is in a unique position to be able to have the public help manage brown trout through an Incentivized Harvest program and the offering of a reward as opposed to contracted or federal removal programs. The initial research into the use of this tool is designed to last 3 to 4 years at which time the program will be evaluated for its effectiveness. It is not designed to eliminate brown trout, but to reduce their numbers to pre-2014 levels. Effective harvest and management of brown trout numbers through the Incentivized Harvest program may avoid the need to implement other removal measures along this segment of the Colorado River in the future.

 

How to Participate

The incentivized harvest begins on November 11, 2020. For the next 3 to 4 years, eligible anglers will be offered a reward of $25 per Brown Trout over 6 inches in length removed from the Colorado River between Glen Canyon Dam and the mouth of the Paria River. This reward may vary with the seasons or be adjusted annually, but will typically be in the $25-$33 dollar range.

  • All Arizona fishing regulations must be followed:
    • Everyone 10 years of age and older must have a valid Arizona fishing license.
    • All brown trout must be harvested legally per current Arizona Game & Fish Department guidelines. This includes using barbless hooks and lures, and no live bait.
    • Rainbow trout limits still apply. Know the difference between Brown trout and Rainbow trout. Hooked rainbow trout should be carefully handled and immediately released once the rainbow trout limit is reached.
  • Pick up the official data card and small bag at the Lees Ferry boat ramp or the Lees Ferry fish cleaning station located near the long-term parking area.
  • Register for the harvest by turning in brown trout heads and entrails in the large bags also provided at the same locations along with a filled-out data card placed in each large bag.
  • Only heads from Brown Trout 6-inches or greater will be counted.
    • Fishing officials can determine body length from head size for 6-inch fish. They can also determine, whether the fish were locally caught, and the difference between brown and rainbow trout. Please only turn in fish from the identified fishing area.
  • Harvested fish and data cards should be turned in at the collection station located at the Navajo Bridge Interpretive Center. A freezer is available for depositing your catch.
  • All brown trout harvested will be tallied at the end of each month. Checks for the rewards (currently $25 per head) will be mailed to the name and address presented on the data card.
  • Our friends and partners at Glen Canyon Conservancy will manage the storage of fish heads and distribution of monthly rewards.
  • NPS employees are not eligible to participate.

For More Information Contact:

Jeff Arnold, Fisheries Biologist, National Park Service (928) 608-6504
Scott Rogers, Aquatic Program Manager, Arizona Game and Fish Department (928) 214-1245

 

Last updated: November 16, 2020

Contact the Park

Mailing Address:

PO Box 1507
Page, AZ 86040

Phone:

(928) 608-6200
Receptionist available at Glen Canyon Headquarters from 7 am to 4 pm MST, Monday through Friday. The phone is not monitored when the building is closed.

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