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ID: Evaluating the Biological Effectiveness of Angler Harvest Incentive Programs
Evaluating the Biological Effectiveness of Angler Harvest Incentive Programs
Type: 
Subjects: 
Item 

        Evaluating the Biological Effectiveness of Angler Harvest Incentive Programs    

                    Description: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.
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ID: Evaluating the Genetic Purity of Western Slope Native Suckers
Evaluating the Genetic Purity of Western Slope Native Suckers

Type: 
Subjects: 
Item 

        Evaluating the Genetic Purity of Western Slope Native Suckers

    

                    Description:Led By
Kevin Tho​mpson​, Jenn Logan
Study Area
Colorado River Basin
Project Status
Ongoing
Research Objectives

To characterize Colorado-wide genetic diversity and purity among native sucker populations.
To ensure proper geographic representation of each species of sucker in brood stocks at CPW's Native Aquatic Species Restoration Facility (NASRF) in Alamosa.
To determine whether CPW researchers and biologists are encountering hybrid suckers that appear pure and to gauge accuracy in identifying which parental species are involved in hybrid specimens.
Photos:Top right: Mouth of Pure Bluehead SuckerBottom right: Mouth of Bluehead/White Sucker Hybrid
​Project Description
Flannelmouth and bluehead sucker populations have declined in recent years, prompting CPW to focus efforts towards protecting and enhancing existing populations of these ecologically important fishes. Both flannelmouth and bluehead suckers will hybridize with non-native sucker species introduced to the Western Slope, threatening the genetic purity of the natives. To combat this problem or to re-establish populations of the native suckers, CPW needs to prepare for the use of captive-reared fish, necessitating the establishment of one or more brood stocks for each species.
Therefore, CPW initiated a study to characterize the genetic purity and diversity of suckers from river drainages across Colorado. To do so, researchers and biologists collected genetic samples from pure suckers to establish reference populations with which future genetic specimens could be compared. Afterwards, hundreds more samples were collected from numerous locations around the Western Slope to assess which populations remain the purest and also to determine how genetically diverse the various populations are. Results from this study helped determine how many brood stocks of each species CPW should maintain at NASRF in order to appropriately represent the genetic diversity of wild populations.
At the time of sampling, collectors attempted to visually identify the species of each sucker and several photographs were taken. Some fish of each species and each hybrid combination were retained as specimens for archiving and future study, as well as for future training in identification. Each genetic sample was analyzed and assigned to species or species mixes for hybrids. Genetic identifications were then compared to field identifications to assess agreement.  ​
We discovered that biologists and researchers were quite accurate in identifying pure fish versus hy​brid fish; however, identification of which parental species were represented in hybrid fish was very challenging especially when more than two ancestral species were represented in hybrid fish.
​Video: Bluehead Sucker Spawning​

​A rare view of these beautifully colored Colorado native Bluehead Suckers showing spawning behavior in the Roubideau Creek drainage near Delta, Colorado. Shot by a BLM employee in May 2012, this is a sight rarely seen in Colorado because the water is usually much less clear during the runoff when these fish spawn. You will see several brightly colored males attending to a single, less colored female. [show more]                

ID: Evaluating the Influence of Human Harvest, Carnivores, Climate, and Habitat on Female Elk Survival Across Western North America
Evaluating the Influence of Human Harvest, Carnivores, Climate, and Habitat on Female Elk Survival Across Western North America
Type: 
Subjects: 
Item 

        Evaluating the Influence of Human Harvest, Carnivores, Climate, and Habitat on Female Elk Survival Across Western North America    

                    Description:Led ByJedediah Brodie, Heather ​Johnson (CPW), Michael Mitchell, Peter Zager, Kelly Proffitt, Mark Hebblewhite, Matthew Kauffman, Bruce Johnson, John Bissonette, Chad Bishop (CPW), Justin Gude, Jeff Herbert, Kent Hersey, Mark Hurley, Paul Lukacs, Scott McCorquodale, Eliot McIntire, Josh Nowak, Hall Sawyer, Douglas Smith and P.J. White
Study AreaWestern North America
Project StatusCompleted
Research Objectives
To determine the relative influence of predation, weather, habitat, land-use and harvest on adult female elk survival.
Project Description
The challenges facing elk management in western landscapes are increasing at a rapid pace as changes to habitat, climate and predator communities influence elk population demography and behavior.
In an effort to understand these new challenges and effectively manage elk in the future, researchers across seven states in western North America began to communicate about shared management challenges and research needs. Collaborators decided that a region-wide study across all the states would provide managers a big-picture view of how broad-scale drivers are influencing elk populations.
Therefore, CPW collaborated with state and federal wildlife agencies in Montana, Idaho, Wyoming, Washington, Oregon and Utah to investigate large-scale temporal and spatial patterns in adult female elk survival and cause-specific mortality. 
Results from this study will help wildlife managers better respond to changing environmental conditions in the future.
Collaborators for this project include personnel from the USGS Montana Wildlife Cooperative Research Unit, USGS Wildlife Cooperative Research Unit, USGS Wyoming Cooperative Research Unit, Idaho Fish and Game, Montana Fish, Wildlife and Parks, Oregon Department of Fish and Wildlife, Washington Department of Fish and Wildlife, Utah Division of Wildlife Resources, Wyoming Game and Fish Department, and Yellowstone National Park.
Associated Publications
Brodie, J., H. Johnson, M. Mitchell, P. Zager, K. Proffitt, M. Hebblewhite, M. Kauffman, B. Johnson, J. Bissonette, C. Bishop, J. Gude, K. Hersey, M. Hurley, P. Lukacs, S. McCorquodale, E. McIntire, J. Nowak, D. Smith, and P.J. White. 2013. Relative influence of human harvest, carnivores, and weather on adult female elk survival across western North America. Journal of Applied Ecology 50:295-305.
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ID: Evaluation of alternative population monitoring strategies for greater sage-grouse (Centrocercus urophasianus) in the Parachute-Piceance-Roan population of northwestern Colorado
Evaluation of alternative population monitoring strategies for greater sage-grouse (<em>Centrocercus urophasianus</em>) in the Parachute-Piceance-Roan population of northwestern Colorado
Type: Text
Subjects: Greater sage-grouse
<em>Centrocercus urophasianus</em>
Parachute-Piceance-Roan (PPR) region
Wildlife management
Northwestern Colorado
Item 

        Evaluation of alternative population monitoring strategies for greater sage-grouse (<em>Centrocercus urophasianus</em>) in the Parachute-Piceance-Roan population of northwestern Colorado    
Type:Text
Subject:Greater sage-grouse
<em>Centrocercus urophasianus</em>
Parachute-Piceance-Roan (PPR) region
Wildlife management
Northwestern Colorado

                    Description:Robust estimates of population size and population trends provide the scientific basis for managers to make appropriate and defensible recommendations regarding land-use decisions, harvest regulations, and mitigation efforts for wildlife. When linked with environmental variables, robust monitoring programs also allow managers to examine wildlife responses to disease, land-use patterns, habitat treatments, weather, ecological succession, and disturbance. However, many wildlife monitoring programs continue to use untested population indices that may not provide reliable information on population status or trends. For this reason, it is essential to evaluate alternative approaches to population monitoring in terms of estimator precision, cost, practicality, and level of disturbance. Lek counts are the primary index used by state wildlife agencies to monitor changes in greater sage-grouse (Centrocercus urophasianus) abundance, but lek counts rely on untested assumptions about lek attendance, detectability, inter-lek movement, sex ratio, and proportion of leks counted. Given the availability of new methodological and statistical approaches to estimate wildlife populations, it is worth comparing the performance of lek counts against other monitoring methods. [show more]                

ID: Evaluation of an Electric Fish Barrier on the South Canal, an Irrigation Ditch on the Lower Gunnison River, Colorado
Evaluation of an Electric Fish Barrier on the South Canal, an Irrigation Ditch on the Lower Gunnison River, Colorado
Type: 
Subjects: 
Item 

        Evaluation of an Electric Fish Barrier on the South Canal, an Irrigation Ditch on the Lower Gunnison River, Colorado    

                    Description:Led By
Dan Kowalski​​
Study Area
South Canal of the Gunnison River
Project Status
Complete
Research Objectives
To monitor fish population trends in the canal and evaluate the effectiveness of an electric fish barrier in reducing fish entrainment through a marked fish study
Project Description
There are over 105,000 irrigation structures on rivers and streams across Colorado, most in fish-bearing waters.  Fish entrainment in irrigation canals is known to be a large problem in the western U.S. but its impact on fish populations in Colorado is unknown.  The South Canal, an irrigation ditch in southwest Colorado, diverts about 360,000 acre feet of water each year (around 1,000 cfs per day) from the Gunnison River into the Uncompahgre Valley for agricultural irrigation use.  With the construction of several new hydropower plants on the canal in 2012, CPW expected to see an increase in fish mortality and impacts to recreational fishing in the South Canal and Uncompahgre River.
In order to reduce impacts on the Gunnison River's Gold Medal trout fishery, an electric fish barrier was installed at the east portal of the canal. Consisting of a series of vertically suspended electrodes, the system aims to discourage brood stock fish from entering the canal and potentially dying in the hydropower turbines.
CPW initiated a study to compare fish populations in the canal before and after the barrier was built and to document fish movement across the barrier with tagged fish. 
Study results revealed that some fish passed through the barrier and survived the turbines, with more small fish successfully passing than large fish. Fish population estimates in the canal have declined after the electric barrier, but not significantly at the 95% level. A total of 288 tagged fish less than 12 inches and four fish greater than 12 inches were recovered below the barrier.  No fish greater than 16 inches have been documented crossing the barrier.  Only 1.3% of all tagged fish were documented to have been entrained in the canal while the barrier was operating. 
The electric barrier appears to successfully exclude larger fish from the study reach, but not age 1 and age 0 trout. The electric fish barrier is successful in its stated objective, but not in reducing overall fish densities in the canal because the growth and survival of smaller fish maintains a stable population of fish in the canal. Reducing the entrainment of large fish is likely a benefit to the trout population of the Gunnison River. Further study is needed to evaluate if smaller trout can be successfully excluded by the electric barrier.
Associated Publication
Evaluation of an Electric Fish Barrier on the South Canal, an Irrigation Ditch on the Lower Gunnison River, Colorado 
Fact Sheet: Electric Fish Barrier Research
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ID: Evaluation of an electric fish barrier on the South Canal, an irrigation ditch on the lower Gunnison River, Colorado
Evaluation of an electric fish barrier on the South Canal, an irrigation ditch on the lower Gunnison River, Colorado
Type: Text
Subjects: Sport fish
Fishing
South canal
Research
Item 

        Evaluation of an electric fish barrier on the South Canal, an irrigation ditch on the lower Gunnison River, Colorado    
Type:Text
Subject:Sport fish
Fishing
South canal
Research

                    Description:An electric fish barrier was installed on the east portal of South Canal to reduce fish entrainment associated with the construction of two hydropower plants in 2012. The objective of this study was to monitor fish entrainment and evaluate the effectiveness of the barrier. Three groups of fish were tagged and released upstream of the barrier; fish from the canal, wild Gunnison River fish, and hatchery reared fingerlings. Mark recapture boat electrofishing was completed and population estimates were made with the Huggins Closed Capture model using fish length to model capture probabilities. The study reach contained 2,994 ± 1,043 fish (>150 mm) in October 2011, 1,764 ± 279 in October 2013, 1,224 ± 239 in July 2014 and 1,900 ± 379 in October 2014. Fish population estimates have declined after the electric barrier, significantly at the 95% level for brown trout but not for rainbows. A total of 288 tagged fish less than 300 mm and four fish greater than 300 mm were recovered below the barrier, representing 1.3% of all tagged fish. The electric barrier appears to meet its objective and successfully exclude larger fish from the study reach, but not smaller age 0, age 1, or age 2 trout. The entrainment, growth and survival of smaller fish maintains a stable population of fish in the canal, but fewer entrained mature fish is likely a benefit to the fish population of the Gunnison River. Further study is needed to evaluate if smaller adult trout can be successfully excluded by the electric barrier with operational modifications. [show more]                

ID: Evaluation of Longrie-Fectau fish passage structure
Evaluation of Longrie-Fectau fish passage structure
Type: 
Subjects: Longrie-Fectau fish passage structure
Item 

        Evaluation of Longrie-Fectau fish passage structure    
Subject:Longrie-Fectau fish passage structure

                    Description:Abstract: Connectivity is critical for freshwater fish conservation, and the design of fish passage structures is a tradeoff between the space available for construction, slope, and costs associated with the structure. The Longrie-Fectau fish passage structure was designed to be modular, readily deployable, and site-generic. To accomplish this, it was designed as two prefabricated portions (straight and curved) that can be quickly installed and accommodate various barrier heights by adding or removing sections. Additionally, the length of straight sections can be altered to fit any site. The sinuous passage design allows a relatively low grade (2%) and passage over large structures with short apron space. The individual pre-cast costs were $9,000 for each of the straight sections, and $6,000 for each of the curved sections. The foundation required to support the pre-cast sections was approximately $4,000 per section. Other financial considerations that will vary depending on the site include the passage entrance and exit, the cap to limit sheet flow over the passage, diverting and dewatering the creek during construction, and additional foundation construction to support the pre-cast sections. We evaluated fish passage through this structure in Fountain Creek, Colorado via a PIT tag mark-recapture study. We documented four Great Plains native fish species successfully ascending the passage structure, with most passage occurring at night. We estimated a 3% probability of a released fish encountering the first array, indicating attraction flows are important consideration for passage design. However, once in the structure, there was a high probability of complete passage (89%). Although this particular structure is large (123 m), passage was relatively fast once fish entered, with median time of successful ascent of 19 minutes and fastest successful passage of six minutes. While fish passage often requires site-specific engineering and design, the Longrie-Fectau-style fish passage design is an option that may reduce construction costs due to its modularity and simplicity. [show more]                

ID: Evaluation of techniques to reduce deer and elk damage to agricultural crops
Evaluation of techniques to reduce deer and elk damage to agricultural crops
Type: Article
Subjects: Cervus elaphus nelsoni
Crop damage
Electric fence
Elk
Mule deer
Odocoileus hemionus
Repellent
Sunflowers
Wildlife damage management
Winged fence
Item 

        Evaluation of techniques to reduce deer and elk damage to agricultural crops    
Type:Article
Subject:Cervus elaphus nelsoni
Crop damage
Electric fence
Elk
Mule deer
Odocoileus hemionus
Repellent
Sunflowers
Wildlife damage management
Winged fence

                    Description:Mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus nelsoni) provide important recreational, ecological, and economic benefits, but can also cause substantial damage to agricultural crops. Cervid damage to agriculture creates challenges for wildlife agencies responsible for minimizing crop depredation while maintaining healthy deer and elk populations. Sunflower producers in southwestern Colorado, USA, have experienced high deer and elk damage and were interested in temporary methods to reduce damage that were cost-effective for rotational crops. To address this challenge, we investigated 3 temporary, non-lethal exclusion and repellent techniques for reducing deer and elk damage to sunflowers: 1) a polyrope electric fence, 2) the chemical repellent Plantskydd™, and 3) a winged fence. During July through October 2011 and 2012, we used a randomized block design to test the efficacy of these techniques by quantifying cervid damage to sunflowers and the number of deer and elk tracks traversing treatment and control plot boundaries. Using generalized linear mixed models we found that polyrope electric fences reduced deer and elk damage and presence within plots, while the repellent and winged fences did not reduce ungulate activity. Polyrope electric fences may be a suitable tool in areas where wildlife management agencies want to maintain deer and elk populations but reduce seasonal damage by cervids to high-value crops. In Colorado, use of an effective exclusion technique such as polyrope electric fence could also decrease the need for lethal depredation permits and damage compensation payments, and increase satisfaction among producers and the public. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. [show more]                

ID: Evaluation of translocation of black bears involved in human–bear conflicts in South-central Colorado
Evaluation of translocation of black bears involved in human–bear conflicts in South-central Colorado
Type: Article
Subjects: Black bear
Cause-specific mortality
Colorado
Conflict
Homing
Survival
Translocation
<em>Ursus americanus</em>
Item 

        Evaluation of translocation of black bears involved in human–bear conflicts in South-central Colorado    
Type:Article
Subject:Black bear
Cause-specific mortality
Colorado
Conflict
Homing
Survival
Translocation
<em>Ursus americanus</em>

                    Description:From 1995 to 1997, black bears (Ursus americanus) involved in conflicts with humans in southeastern Colorado, USA, were radiocollared, translocated, and monitored by the Colorado Division of Wildlife to evaluate translocation as a management tool for problem black bears. Specific objectives were to 1) determine postrelease movement patterns of relocated black bears, and 2) estimate cumulative incidence and survival functions. Subadults did not move as far after translocation as adults and less frequently oriented toward the capture site (29% of subad vs. 51% of ad). No subadults returned to the vicinity of capture, whereas 33% of adults did. We used a cause-specific hazards model with a constant age effect across the cause-specific hazards to estimate annual survival rate for translocated adult bears (0.50, 95% credible interval CI = 0.36–0.65) and for subadult bears (0.28, 95% CI = 0.12–0.48). The annual probability of dying due to repeat conflict behavior was slightly lower (0.22 [95% CI = 0.13–0.33] and 0.32 [95% CI = 0.19–0.47]) for adults and subadults, respectively, compared with nonconflict mortalities (0.28 [95% CI = 0.17–0.40] and 0.40 [95% CI = 0.25–0.56]). Based on bears that were not involved in known repeat human–bear conflicts, translocation success was 0.64 (95% CI = 0.49–0.78) and 0.58 (95% CI = 0.42–0.73) for adults and subadults, respectively. Translocation of problem bears had mixed success relative to repeat nuisance activity in Colorado, but should remain a viable management option. Managers should make decisions on the appropriateness of translocation based on the characteristics of the bear, identification of an adequate release site, potential effect of the translocation on the release-site bear population, and other available options. [show more]                

ID: Evaluation of winter range habitat treatments on overwinter survival, density, and body condition of mule deer
Evaluation of winter range habitat treatments on overwinter survival, density, and body condition of mule deer
Type: Text
Subjects: Colorado
Mule deer
Management
Habitat
Item 

        Evaluation of winter range habitat treatments on overwinter survival, density, and body condition of mule deer    
Type:Text
Subject:Colorado
Mule deer
Management
Habitat

                    Description:The management and research of mule deer (Odocoileus hemionus) in Colorado and throughout the Rocky Mountain West is an exciting arena for wildlife professionals as the prevailing view among biologists, managers, researchers, hunters, wildlife viewers and general wildlife enthusiasts is that they would like to see more deer on the landscape. This desire, and the subsequent support it generates for mule deer research, has paved the way for research projects to evolve: each project has generated new data, new knowledge and answers to questions, but each projected has also generated new questions. My research has been a part of this evolution; it benefited from and was built on existing information, it adds new knowledge and hopefully, it will help guide future research. [show more]                