Evaluating the Biological Effectiveness of Angler Harvest Incentive Programs

Led By

Lake and Reservoir Researchers

Study Area

Select reservoirs

Project Status

Ongoing

Research Objectives

• Monitor the response of target fishes to incentivized angling.
• Monitor the participation and harvest dynamics of anglers.
• Develop population models and other quantitative tools to inform the biological effectiveness of ongoing incentivized angling efforts.

Project Description

CPW strives to provide the best sport fishing opportunities that are appropriate for each water body in the state of Colorado. Opportunities in some locations may not be appropriate for others given differences in management objectives, the need to protect native fish species in sensitive locations, the need to maintain wild broodstocks that provide valuable eggs to the states hatchery system, or other ecological factors. 

One example is the presence of nonnative predatory sport fish like smallmouth bass and northern pike stocked historically or illegally into some reservoirs on the western slope of Colorado that are located upstream of critical river and stream habitats for unique native fishes. The presence of these predatory fish undermines conservation efforts because they can escape the reservoirs, establish populations downstream, and eat or compete with native fish.

One of CPW’s missions is to protect native species that represent the ecology and natural history of the state. Sometimes, management actions to limit nonnative predatory sport fish in unwanted locations is necessary. Therefore, CPW has been implementing fishing tournaments in locations like Ridgway (southwest Colorado) and Elkhead (northwest Colorado) reservoirs where anglers can win cash prizes by helping CPW remove unwanted predatory fishes from the reservoirs to favor more compatible sport fish species.    

Harvest of sport fish is also sometimes needed for reasons other than native fish protection. For example, the need to maintain predator-prey balance in systems like Blue Mesa Reservoir (southwest Colorado) where consumption of stocked kokanee salmon by naturally reproducing lake trout can become unsustainable. Here, periodic harvest incentives are used to remove overabundant small lake trout (greatest predation impact on juvenile kokanee based on previous research) to help maintain the adult kokanee population where needed for egg-collection purposes and to maintain angling opportunities for trophy (even world record) lake trout.

In both contexts, Lake and Reservoir Researchers have been working alongside managers collecting additional biological information and developing quantitative survey or modeling tools to inform the effectiveness of these angler incentive programs, identify potential avenues for increasing effectiveness if necessary, and to enable adaptive decision making.              

Associated Publications

Cristan, E.T. 2021. Angler incentives: lucrative lake trout in Blue Mesa Reservoir. Colorado Outdoors Magazine. September/October Issue, Vol. 70, No. 5.

Hansen, A.G., J.M. Lepak, E.I. Gardunio, and T. Eyre. 2024. Evaluating harvest incentives for suppressing a socially-valued, but ecologically-detrimental, invasive fish predator. Fisheries Management and Ecology 31:e12699.

Pate, W.M., B.M. Johnson, J.M. Lepak, and D. Brauch. 2014. Managing for coexistence of kokanee and trophy lake trout in a montane reservoir. North American Journal of Fisheries Management 34:908-922.