552 items found

Sort by: Identifier Title Type Subject

ID: Understanding and Managing Mercury Bioaccumulation in Sport Fish
Understanding and Managing Mercury Bioaccumulation in Sport Fish

Type: 
Subjects: 
Item 

        Understanding and Managing Mercury Bioaccumulation in Sport Fish

    

                    Description:Led By
Lake and Reservoir Researchers
Study Area
Statewide
Project Status
Completed
Research Objectives
To better understand the bioaccumulation of mercury in sport fish, inform development of consumption advisories, and minimize health risks to anglers.​
Project Description
According to the Environmental Protection Agency and Food and Drug Administration, fish represent an excellent source of low-calorie protein. However, eating fish with high mercury concentrations can be a potential health risk.
To protect the health of Colorado's anglers and maintain the quality of angling opportunities, the Lake and Reservoir Research group investigates methods to reduce mercury concentrations in fish, and act as sport fish and food web advisor’s to the Colorado Department of Public Health and Environment’s Technical Advisory Committee on mercury advisories.
A recent study on Narraguinnep Reservoir (southwest Colorado) conducted by CPW and researchers from Colorado State University found that ‘triploid’ walleye (have a third set of chromosomes and cannot reproduce naturally) stocked by CPW had 22-24% lower mercury concentrations on average than their normal, naturally-reproducing ‘diploid’ counterparts. This study revealed that stocking triploid fish alone or in tandem with other mitigation strategies can lead to safer fish for anglers to eat.
The inability of triploid walleye to reproduce affects their mercury levels. Spawning is energetically costly, particularly for female fish that need to develop eggs. As a result, normal, diploid walleye need to eat more food to grow and successfully spawn every year when compared to triploid walleye. Since most (>95%) of the mercury present in predatory fish comes from their prey, eating less food to grow the same amount means triploid fish are exposed to less mercury, and have lower mercury concentrations.
Another recent study was conducted in Colorado to determine the best predictors of mercury concentrations in small walleye and smallmouth bass (15 inches) and large (34 inches) northern pike. We used a machine learning approach to test the different predictors and found that the best predictors of walleye and smallmouth bass mercury concentrations where system-specific measurements of productivity and forage base quality (the higher the productivity and quality of the forage base, the lower the mercury concentrations). The best predictors of large northern pike mercury concentrations were related to the stocking of catchable rainbow trout. Data indicated that large northern pike often eat stocked rainbow trout, and as a result, northern pike mercury concentrations can be lower where heavy rainbow trout stocking occurs (diluted by high calorie prey containing relatively little mercury). This approach could be applied to identify potential areas/systems of concern, and predict whether sport fish Hg concentrations may change as a result of a variety of factors to help prioritize, focus, and streamline monitoring efforts to effectively and efficiently inform human and ecological health.
Associated Publications
Farrell, C.J., B.M. Johnson, A.G. Hansen, and C.M. Myrick. 2022. Induced triploidy reduces mercury bioaccumulation in a piscivorous fish. Canadian Journal of Fisheries and Aquatic Sciences 79:202-212 (Received Editor’s Choice Award).
Eagles-Smith, C.A., J.G. Wiener, C. Eckley, J.J. Willacker, D.C. Evers, M. Marvin-DiPasquale, D. Obrist, J. Fleck, G. Aiken, J.M. Lepak, A.K. Jackson, J. Webster, A.R. Stewart, J. Davis, C. Alpers, and J.T. Ackerman. 2016. Mercury in western North America: a synthesis of environmental contamination, fluxes, bioaccumulation and risk to fish and wildlife. Science of the Total Environment 568:1213-1226.
Eagles-Smith, C.A., J.T. Ackerman, J.J. Willacker, M.T. Tate, M.A. Lutz, J. Fleck, A.R. Stewart, J.G. Wiener, D.C. Evers, J.M. Lepak, J. Davis, and C. Flanagan Pritz. 2016. Spatial and temporal patterns of mercury concentrations in freshwater fishes across the Western US and Canada. Science of the Total Environment 568:1171-1184.
Jackson, A., D.C. Evers, C.A. Eagles-Smith, J.T. Ackerman, J.J. Willacker, J.T. Elliott, J.M. Lepak, S.S. VanderPol, and C.E. Bryan. 2016. Mercury risk to avian piscivores across the western United States and Canada. Science of the Total Environment 568:685-696.
Johnson, B.M., J.M. Lepak, and B.A. Wolff. 2015. Effects of prey assemblage on mercury bioaccumulation in a piscivorous sport fish. Science of the Total Environment 506-507:330-337.
Lepak, J.M., M.B. Hooten, C.A. Eagles-Smith, M.T. Tate, M.A. Lutz, J.T. Ackerman, J.J.Jr.  Willacker, D.C. Evers, J.G. Wiener, C. Flanagan Pritz, and J. Davis. 2016. Assessing potential health risks to fish and humans using mercury concentrations in inland fish from across western Canada and the United States. Science of the Total Environment 571:342-354.
Lepak, J.M., M.B. Hooten, and B.M. Johnson. 2012. The influence of external subsidies on diet, growth and Hg concentrations of freshwater sport fish: implications for fisheries management and the development of fish consumption advisories. Ecotoxicology 21(7):1878-1888.
Lepak, J.M., K.D. Kinzli, E.R. Fetherman, W.M. Pate, A.G. Hansen, E.I. Gardunio, C.N. Cathcart, W.L. Stacy, Z.E. Underwood, M.M. Brandt, C.M. Myrick, and B.M. Johnson. 2012. Manipulation of growth to reduce sport fish mercury concentrations on a whole-lake scale. Canadian Journal of Fisheries and Aquatic Sciences 69(1):122-135.
Lepak, J.M., B.A. Wolff, B.M. Johnson M.B. Hooten, and A.G. Hansen. 2023. Predicting sport fish mercury contamination in heavily managed reservoirs: implications for human and ecological health. PLOS ONE 18:e0285890.
Stacy, W.L., and J.M. Lepak. 2012. Relative influence of prey mercury concentration, prey energy density and predator sex on sport fish mercury concentrations. Science of the Total Environment 437:104-109.
Taylor, M.S., C.T. Driscoll, J.M. Lepak, D.C. Josephson, K.J. Jirka, and C.E. Kraft. 2020. Temporal trends in fish mercury concentrations in an Adirondack Lake managed with a continual predator removal program. Ecotoxicology 29:1762-1773.
Willacker, J.J., C.A. Eagles-Smith, M.A. Lutz, M.T. Tate, J.T. Ackerman, and J.M. Lepak. 2016. The influence of reservoirs and their water management on fish mercury concentrations in Western North America. Science of the Total Environment 568:739-748.
Wolff, B.A., B.M. Johnson, and J.M. Lepak. 2017. Changes in sport fish mercury concentrations from food web shifts suggest partial decoupling from mercury loading in two Colorado reservoirs. Archives of Environmental Contamination and Toxicology 72:167-177.
 [show more]                

ID: Understanding Mercury Bioaccumulation in Sport Fish
Understanding Mercury Bioaccumulation in Sport Fish

Type: 
Subjects: 
Item 

        Understanding Mercury Bioaccumulation in Sport Fish

    

                    Description:Led By
Jesse L​epak​
Study Area
Statewide
Project Status
Ongoing
Research Objectives
To better understand the bioaccumulation of mercury in sport fish.​
Project Description
According to the Environmental Protection Agency and Food and Drug Administration, fish represent an excellent source of low-calorie protein. However, eating fish with high mercury concentrations can be a potential health risk.
To protect the health of Colorado's anglers and maintain the quality of angling opportunities, the Lake and Reservoir Research group investigates methods to reduce mercury concentrations in fish.
For example, researchers conducted a study to determine if manipulating predatory sport fish growth would decrease mercury concentrations. For this particular project, researchers monitored a northern pike (top predator) population in College Lake, a 25-hectare reservoir located on the Colorado State University Foothills Research Campus in Fort Collins, Colo. Researchers took tissue biopsies from northern pike before and two months after College Lake was stocked with rainbow trout, a high energy, low-mercury concentration prey species. The result was a decrease in northern pike mercury concentrations equivalent to their weight gain (with some fish gaining over 35 percent of their own body weight in two months with a corresponding reduction in mercury concentration of approximately 35 percent).
Results from the study showed that stocking high quality, low-mercury prey is a rapid and effective method to reduce sport fish concentrations. However, researchers found that this method is only temporarily effective; once the stocked prey fish are all eaten, predatory fish growth slows and mercury concentrations return to their former levels. Continuously stocking prey fish can be expensive, especially in large lakes and reservoirs. Thus, results from this study revealed that managing for naturally occurring and reproducing populations of prey fish with high energy and low-mercury concentrations would be more economically and ecologically beneficial.
The Lake and Reservoir Rese​arch group will continue to characterize and potentially minimize health risks posed by mercury to anglers, their families and wildlife that consume sport fish and other fish. ​
Associated Publications
Lepak, J.M., Hooten, M.B., and Johnson, B.M. 2012. The influence of external subsidies on diet, growth and Hg concentrations of freshwater sport fish: implications for fisheries management and the development of fish consumption advisories. Ecotoxicology. 21(7):1878-1888.​
Stacy, W.L., and Lepak, J.M. 2012. Relative influence of prey mercury concentration, prey energy density and predator sex on sport fish mercury concentrations. Science of the Total Environment. 437:104-109.
Lepak, J.M., Kinzli, K.D., Fetherman, E.R., Pate, W.M., Hansen, A.G., Gardunio, E.I., Cathcart, C.N., Stacy, W.L., Underwood, Z.E., Brandt, M.M., Myrick, C.M., and Johnson, B.M.  2012. Manipulation of growth to reduce sport fish mercury concentrations on a whole-lake scale. Canadian Journal of Fisheries and Aquatic Sciences. 69(1):122-135.
 [show more]                

ID: Upper Arkansas River Habitat Enhancement Evaluation
Upper Arkansas River Habitat Enhancement Evaluation

Type: 
Subjects: 
Item 

        Upper Arkansas River Habitat Enhancement Evaluation

    

                    Description:Led By
Eric Richer​ and Matt Kondratieff 
Study Area
Upper Arkansas River within the Crystal Lakes STL, Reddy SWA, and Hayden Flats
Project Status
Ongoing
Research Objectives
To evaluate effectiveness of stream restoration and habitat enhancement treatments
To monitor the fishery response to habitat restoration
To utilize creel surveys to evaluate angler experience in restored areas​
​​​Project Description
The objectives of the Upper Arkansas River Habitat Restoration project are to rehabilitate and enhance aquatic habitat for an 11-mile reach of the Arkansas River and Lake Fork on both public and private lands. Funding for this project was obtained under the Natural Resource Damage Assessment (NRDA) provisions of CERCLA for harm to natural resources due to hazardous substances released from the California Gulch Superfund Site. This project is designed to improve fish populations in the Arkansas River as compensation to the public. Colorado Parks and Wildlife (CPW) is responsible for habitat restoration and enhancement on approximately five miles of public lands within the Crystal Lakes State Trust Lands (STL), Reddy State Wildlife Area (SWA) and Hayden Flats Arkansas Headwaters Recreation Area.
The NRDA Trustees Council established the following goals for the restoration project:
Increase trout population density and biomass, including improvement in body condition and fish health.
Improve age and size class structure by increasing spawning areas where possible and provide refugia for juvenile trout and other native fish.
These goals will be achieved by: stabilizing stream banks and promoting diverse stream morphology; reducing erosion and downstream sedimentation; enhancing overhead cover for trout; and creating diverse in-stream habitat including pools, riffles, and bars.
CPW's Aquatic Research Section is responsible for monitoring and evaluating the effectiveness of the restoration project in cooperation with researchers at Colorado State University, Colorado Mountain College and the​ US Fish and Wildlife Service. Additional information on the project can be found in the publications listed below. ​
Associated Publications
​​Richer, E.E., E.A. Gates, A.T. Herdrich, and M.C. Kondratieff. 2017. Upper Arkansas River habitat restoration project: 2013-2015 monitoring report. Colorado Parks and Wildlife Technical Publication 49.
Brinkman, S.F., P.H. Davies, D. Hansen, and N. Vieira. 2006. Arkansas River Research Study​. Colorado Division of Wildlife, Fort Collins, Colorado. 153 pp. ​
Stratus Consulting, Inc. 2010. Draft restoration monitoring and outreach plan for the upper Arkansas River watershed. Boulder, Colorado. 63 pp. 
 [show more]                

ID: Upper Arkansas River instream habitat restoration project:

2020 annual site assessment
Upper Arkansas River instream habitat restoration project:

2020 annual site assessment
Type: Text
Subjects: Upper Arkansas River
Habitat restoration
Item 

        Upper Arkansas River instream habitat restoration project:

2020 annual site assessment    
Type:Text
Subject:Upper Arkansas River
Habitat restoration

                    Description:Monitoring activities to evaluate restoration effectiveness for the upper Arkansas River Habitat Restoration Project were conducted by Colorado Parks and Wildlife (CPW) and contractors during 2020 and 2021. Efforts were primarily focused on data analysis and publication of results for monitoring targets, including fish populations, riparian vegetation, benthic macroinvertebrates, instream habitat structures, and water quality. Some fish population, benthic macroinvertebrate, riparian vegetation and habitat metrics improved following restoration, although not all metrics have achieved target goals. Significant improvements in Brown Trout Salmo trutta density, biomass and condition were encouraging, but apparent declines in quality trout could be indicative of increased competition or limited forage. The abundance of benthic macroinvertebrates increased, but not to the level of project goals. Woody riparian vegetation increased significantly, and encroachment of riparian vegetation has outpaced bank erosion, which suggests that bank stability has improved and the channel is moving towards dynamic equilibrium. Multiple metrics indicate that ecosystem health within the California Gulch Superfund Site continues to improve. [show more]                

ID: Urbanization impacts apex predator gene flow but not genetic diversity across an urban‐rural divide
Urbanization impacts apex predator gene flow but not genetic diversity across an urban‐rural divide
Type: Article
Subjects: Effective population size
Gene flow
Landscape genomics
<em>Puma concolor</em>
Urbanization
Genetic diversity
Item 

        Urbanization impacts apex predator gene flow but not genetic diversity across an urban‐rural divide    
Type:Article
Subject:Effective population size
Gene flow
Landscape genomics
<em>Puma concolor</em>
Urbanization
Genetic diversity

                    Description:Apex predators are important indicators of intact natural ecosystems. They are also sensitive to urbanization because they require broad home ranges and extensive contiguous habitat to support their prey base. Pumas (Puma concolor) can persist near human developed areas, but urbanization may be detrimental to their movement ecology, population structure, and genetic diversity. To investigate potential effects of urbanization in population connectivity of pumas, we performed a landscape genomics study of 130 pumas on the rural Western Slope and more urbanized Front Range of Colorado, USA. Over 12,000 single nucleotide polymorphisms (SNPs) were genotyped using double-digest, restriction site-associated DNA sequencing (ddRADseq). We investigated patterns of gene flow and genetic diversity, and tested for correlations between key landscape variables and genetic distance to assess the effects of urbanization and other landscape factors on gene flow. Levels of genetic diversity were similar for the Western Slope and Front Range, but effective population sizes were smaller, genetic distances were higher, and there was more admixture in the more urbanized Front Range. Forest cover was strongly positively associated with puma gene flow on the Western Slope, while impervious surfaces restricted gene flow and more open, natural habitats enhanced gene flow on the Front Range. Landscape genomic analyses revealed differences in puma movement and gene flow patterns in rural versus urban settings. Our results highlight the utility of dense, genome-scale markers to document subtle impacts of urbanization on a wide-ranging carnivore living near a large urban center. [show more]                

ID: Use of predictive distribution models to describe habitat selection by bats in Colorado, USA
Use of predictive distribution models to describe habitat selection by bats in Colorado, USA
Type: Article
Subjects: Bats
Bayesian regression analysis
Colorado
Habitat selection modeling
Pinyon‐juniper
Presence‐only data
Probability of use
Item 

        Use of predictive distribution models to describe habitat selection by bats in Colorado, USA    
Type:Article
Subject:Bats
Bayesian regression analysis
Colorado
Habitat selection modeling
Pinyon‐juniper
Presence‐only data
Probability of use

                    Description:Numerous processes operating at landscape scales threaten bats (e.g., habitat loss, disease). Temperate bat species are rarely examined at commensurate scales because of logistical and modeling constraints. Recent modeling approaches now allow for presence-only datasets, like those often available for bats, to assist with the development of predictive distribution models. We describe the use of presence-only data and rigorous predictive distribution models to examine habitat selection by bats across Colorado, USA. We applied hierarchical Bayesian models to bat locations from 1906–2018 to examine relationships of 13 species with landscape covariates. We considered differences in type of activity (foraging, roosting, hibernation), seasonality (summer vs. winter), and scale (1, 5, 10, and 15-km buffers). These findings generated statewide probability of use models to guide management of bat species in response to threats (e.g., white-nose syndrome [WNS]). Analysis of buffers suggest selection of land cover and environmental covariates occurs at different scales depending on the species and activity. Pinyon (Pinus spp.)-juniper (Juniperus spp.) appeared as a positive association in the highest number of models, followed by montane woodland, supporting the importance of these forest types to bats in Colorado. Other covariates commonly associated with bats in Colorado include westerly longitudes, and negative associations with montane shrubland. Mechanical treatments within pinyon-juniper and montane woodlands should be conducted with caution to avoid harming bat communities. We developed hibernation models for only 2 species, making apparent the lack of winter records for bat species in the state. We also provide a composite predictive surface of small-bodied bats in Colorado that delineates where these species, vulnerable to WNS, converge. This tool provides managers with focal points to apply surveillance and response strategies for the impending arrival of the disease. [show more]                

ID: Using auxiliary telemetry information to estimate animal density from capture–recapture data
Using auxiliary telemetry information to estimate animal density from capture–recapture data
Type: Article
Subjects: Density
Geographic closure
Mark-recapture
Telemetry
Item 

        Using auxiliary telemetry information to estimate animal density from capture–recapture data    
Type:Article
Subject:Density
Geographic closure
Mark-recapture
Telemetry

                    Description:Estimation of animal density is fundamental to ecology, and ecologists often pursue density estimates using grids of detectors (e.g., cameras, live traps, hair snags) to sample animals at a study site. However, under such a framework, reliable estimates can be difficult to obtain because animals move on and off of the site during the sampling session (i.e., the site is not closed geographically). Generally, practitioners address lack of geographic closure by inflating the area sampled by the detectors based on the mean distance individuals moved between trapping events or invoking hierarchical models in which animal density is assumed to be a spatial point process, and detection is modeled as a declining function of distance to a detector. We provide an alternative in which lack of geographic closure is sampled directly using telemetry, and this auxiliary information is used to compute estimates of density based on a modified Huggins closed-capture estimator. Contrary to other approaches, this method is free from assumptions regarding the distribution and movement of animals on the landscape, the stationarity of their home ranges, and biases induced by abnormal movements in response to baited detectors. The estimator is freely available in Program MARK. [show more]                

ID: Using digital photographs and pattern recognition identify individual boreal toads (Anaxyrus boreas boreas)
Using digital photographs and pattern recognition identify individual boreal toads (<em>Anaxyrus boreas boreas</em>)
Type: Text
Subjects: Boreal Toads
<em>Anaxyrus boreas boreas</em>
Identification
Item 

        Using digital photographs and pattern recognition identify individual boreal toads (<em>Anaxyrus boreas boreas</em>)    
Type:Text
Subject:Boreal Toads
<em>Anaxyrus boreas boreas</em>
Identification

                    Description:Individual identification of animals can provide an array of useful capture-mark-recapture information, allowing researchers to estimate survival, movement, abundance, recruitment, and capture probability (Williams et al. 2002). This information can yield valuable insight to field investigators regarding a species’ life history (Davis and Ovaska 2001; Phillott et al. 2007). Techniques used to identify individuals of many species have been developed and refined to gather this information. Toe clipping, PIT tagging, polymers and pigments, branding, and pattern mapping are all viable techniques for identifying individuals of many amphibian species (Davis and Ovaska 2001, Donnelly et al. 1994). [show more]                

ID: Using digital photographs and pattern recognition to identify individual boreal toads (Anaxyrus boreas boreas)
Using digital photographs and pattern recognition to identify individual boreal toads (<em>Anaxyrus boreas boreas</em>)
Type: Article
Subjects: Boreal Toads
<div class="element-text"><em>Anaxyrus boreas boreas</em></div>
Identification
Item 

        Using digital photographs and pattern recognition to identify individual boreal toads (<em>Anaxyrus boreas boreas</em>)    
Type:Article
Subject:Boreal Toads
<div class="element-text"><em>Anaxyrus boreas boreas</em></div>
Identification

                    Description:Individual identification of animals can provide an array ofuseful capture-mark-recapture information, allowing researchers to estimate survival, movement, abundance, recruitment, and capture probability (Williams et al. 2002). This information can yield valuable insight to field investigators regarding a species’ life history (Davis and Ovaska 2001; Phillott et al. 2007). Techniques used to identify individuals of many species have been developed and refined to gather this information. Toe clipping, PIT tagging,polymers and pigments, branding, and pattern mapping are all viable techniques for identifying individuals of many amphibian species (Donnelly et al. 1994; Davis and Ovaska 2001). [show more]                

ID: Using environmental features to model highway crossing behavior of Canada lynx in the Southern Rocky Mountains
Using environmental features to model highway crossing behavior of Canada lynx in the Southern Rocky Mountains
Type: Article
Subjects: GPS tracking
Habitat models
Interpersonal conflict
Motorized recreation
Non-motorized recreation
Recreation planning
Item 

        Using environmental features to model highway crossing behavior of Canada lynx in the Southern Rocky Mountains    
Type:Article
Subject:GPS tracking
Habitat models
Interpersonal conflict
Motorized recreation
Non-motorized recreation
Recreation planning

                    Description:Carnivores are particularly sensitive to reductions in population connectivity caused by human disturbance and  Forest Fragmentation from ScienceDirect's AI-generated Topic Pages" class="topic-link" target="_blank" rel="noreferrer noopener">habitat fragmentation. Permeability of transportation corridors to carnivore movements is central to species conservation given the large spatial extent of transportation networks and the high mobility of many carnivore species. We investigated the degree to which two-lane highways were permeable to movements of resident Canada lynx in the Southern Rocky Mountains based on highway crossings (n = 593) documented with GPS telemetry. All lynx crossed highways when present in home ranges at an average rate of 0.6 crossings per day. Lynx mostly crossed highways during the night and early dawn when traffic volumes were low. Five of 13 lynx crossed highways less frequently than expected when compared to random expectation, but even these individuals crossed highways frequently in parts of their home range. We developed fine- and landscape-scale resource selection function (RSF) models with field and remotely sensed data, respectively. At the fine scale, lynx selected crossings with low distances to vegetative cover and higher tree basal area; we found no support that topography or road infrastructure affected lynx crossing. At the landscape scale, lynx crossed highways in areas with high forest canopy cover in drainages on primarily north-facing aspects. The predicted crossing probabilities generated from the landscape-scale RSF model across western Colorado, USA, were successful in identifying known lynx crossing sites as documented with independent snow-tracking and road-mortality data. We discuss effective mitigation based on model results. [show more]                