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Full-Text Articles in Physical Sciences and Mathematics

Estimating Waterbird Abundance On Catfish Aquaculture Ponds Using An Unmanned Aerial System, Paul C. Burr, Sathishkumar Samiappan, Lee A. Hathcock, Robert J. Moorhead, Brian S. Dorr Jan 2019

Estimating Waterbird Abundance On Catfish Aquaculture Ponds Using An Unmanned Aerial System, Paul C. Burr, Sathishkumar Samiappan, Lee A. Hathcock, Robert J. Moorhead, Brian S. Dorr

Human–Wildlife Interactions

In this study, we examined the use of an unmanned aerial system (UAS) to monitor fish-eating birds on catfish (Ictalurus spp.) aquaculture facilities in Mississippi, USA. We tested 2 automated computer algorithms to identify bird species using mosaicked imagery taken from a UAS platform. One algorithm identified birds based on color alone (color segmentation), and the other algorithm used shape recognition (template matching), and the results of each algorithm were compared directly to manual counts of the same imagery. We captured digital imagery of great egrets (Ardea alba), great blue herons (A. herodias), …


The Relationship Between Measures Of Annual Livestock Disturbance In Western Riparian Areas And Stream Conditions Important To Trout, Salmon, And Char, Lindsey M. Goss, Brett B. Roper Apr 2018

The Relationship Between Measures Of Annual Livestock Disturbance In Western Riparian Areas And Stream Conditions Important To Trout, Salmon, And Char, Lindsey M. Goss, Brett B. Roper

Watershed Sciences Faculty Publications

Managing livestock disturbance in riparian zones in a manner that provides economic returns to ranchers while protecting streams is an important aspect of rangeland management on public lands in the western United States. Attempts to balance economic and ecologic outcomes have been made more difficult due to the presence of several salmonid species that are protected under the Endangered Species Act. One approach to proper management of livestock use near streams has been to define the allowable limits of disturbance using 2 metrics, streambank alteration and stubble height. We evaluated 153 stream reaches within the Interior Columbia Basin to determine …


A Comparison Of Five Statistical Methods For Predicting Stream Temperature Across Stream Networks, Maike F. Holthuijzen Aug 2017

A Comparison Of Five Statistical Methods For Predicting Stream Temperature Across Stream Networks, Maike F. Holthuijzen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The health of freshwater aquatic systems, particularly stream networks, is mainly influenced by water temperature, which controls biological processes and influences species distributions and aquatic biodiversity. Thermal regimes of rivers are likely to change in the future, due to climate change and other anthropogenic impacts, and our ability to predict stream temperatures will be critical in understanding distribution shifts of aquatic biota. Spatial statistical network models take into account spatial relationships but have drawbacks, including high computation times and data pre-processing requirements. Machine learning techniques and generalized additive models (GAM) are promising alternatives to the SSN model. Two machine learning …


Interdisciplinary Modeling For Water-Related Issues Graduate Course, Laurel Saito, Alexander Fernald, Timothy Link Jul 2015

Interdisciplinary Modeling For Water-Related Issues Graduate Course, Laurel Saito, Alexander Fernald, Timothy Link

All ECSTATIC Materials

The science and management of aquatic ecosystems is inherently interdisciplinary, with issues associated with hydrology, atmospheric science, water quality, geochemistry, sociology, economics, environmental science, and ecology. Addressing water resources issues in any one discipline invariably involves effects that concern other disciplines, and attempts to address one issue often have consequences that exacerbate existing issues or concerns, or create new ones (Jørgensen et al. 1992; Lackey et al. 1975; Straskraba 1994) due to the strongly interactive nature of key processes (Christensen et al. 1996). Thus, research and management of aquatic ecosystems must be interdisciplinary to be most effective, but such truly …


Colorado River Cutthroat Trout Habitat Resistance And Resilience To Climate Change, Kate H. Olsen May 2013

Colorado River Cutthroat Trout Habitat Resistance And Resilience To Climate Change, Kate H. Olsen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Government agencies and private organizations spend large amounts of public money attempting to return ecosystems to a more natural state, which have often been harmed or even destroyed as a result of modern development. Colorado River cutthroat trout, Oncorhyncus clarki pleuriticus, are a subspecies of cutthroat trout. Cutthroat trout live in the Rocky Mountains of the western United States. The population of this particular subspecies has been severely reduced by human actions, and currently only 12% of its historic populations still exist. To improve the condition of cutthroat trout, fisheries professionals and biologists are working to restore natural populations. …


Comparison Of Topographic Surveying Techniques In Streams, Sara G. Bangen May 2013

Comparison Of Topographic Surveying Techniques In Streams, Sara G. Bangen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Bonneville Power Administration (BPA) Fish and Wildlife Program (FWP) mitigates impacts, including mortality, from hydroelectric dams in the Columbia River Basin for ESA-listed salmon and steelhead populations and other species of special concern. Given the extensive economic resources invested in mitigation and the incredible diversity of in-stream habitat across the Columbia River basin, questions have arisen about which sampling strategies are most tractable across the entire Columbia River Watershed, but also produce datasets that allow researchers to answer meaningful questions about salmonid populations and trends in habitat. In response to these issues, the NOAA Integrated Status and Effectiveness Monitoring …


A Study Of The Spawning Ecology And Early Life History Survival Of Bonneville Cutthroat Trout, Phaedra E. Budy, Sarah Wood, Brett B. Roper May 2012

A Study Of The Spawning Ecology And Early Life History Survival Of Bonneville Cutthroat Trout, Phaedra E. Budy, Sarah Wood, Brett B. Roper

Watershed Sciences Faculty Publications

We completed a large-scale field experiment in four tributaries of the Logan River, Utah, where the largest metapopulation of imperiled Bonneville cutthroat trout Oncorhynchus clarkii utah persists. We documented the spatial and temporal distributions of spawners, quantified substrate use versus substrate availability, and evaluated differences in hatch and emergence fry success between and among sites in relation to habitat characteristics. We observed considerable variability in the timing, magnitude, and duration of spawning among study areas (streams), in part as a function of a variable, multipeaked hydrograph. Nevertheless, across study areas, >70% of redds were constructed on the final descending limb …


Mercury In The Pelagic And Benthic Food Webs Of The Great Salt Lake, Wayne A. Wurtsbaugh, Erin Fleming, Caleb Izdepski, Jodi Gardberg Jul 2011

Mercury In The Pelagic And Benthic Food Webs Of The Great Salt Lake, Wayne A. Wurtsbaugh, Erin Fleming, Caleb Izdepski, Jodi Gardberg

Watershed Sciences Faculty Publications

No abstract provided.


Mercury And Selenium Bioaccumulation In The Stromatolite Community Of The Great Salt Lake, Utah, Usa, Wayne A. Wurtsbaugh Jan 2011

Mercury And Selenium Bioaccumulation In The Stromatolite Community Of The Great Salt Lake, Utah, Usa, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

No abstract provided.


Lakes As Buffers Of Stream Dissolved Organic Matter (Dom) Variability: Temporal Patterns Of Dom Characteristics In Mountain Stream-Lake Systems, K. J. Goodman, Michelle A. Baker, Wayne A. Wurtsbaugh Jan 2011

Lakes As Buffers Of Stream Dissolved Organic Matter (Dom) Variability: Temporal Patterns Of Dom Characteristics In Mountain Stream-Lake Systems, K. J. Goodman, Michelle A. Baker, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Lakes within fluvial networks may affect dissolved organic matter (DOM) dynamics in streams by dampening spring DOM snowmelt flushing responses and/or by increasing summer DOM production. We assessed the temporal variability of dissolved organic carbon (DOC) concentration and DOM characteristics (specific ultraviolet absorbance (SUVA254); DOC:dissolved organic nitrogen (DOC:DON)), as well as DOC export in seven paired lake inflows and outflows in the Sawtooth Mountain lake district, Idaho. We hypothesized that lakes would decrease stream DOM temporal variability and increase DOM export as a result of autotrophic production. We correlated DOM variability with landscape factors to evaluate potential drivers of DOM …


Assessing Linkages Among Landscape Characteristics, Stream Habitat, And Macroinvertebrate Communities In The Idaho Batholith Ecoregion, Andrew C. Hill Dec 2010

Assessing Linkages Among Landscape Characteristics, Stream Habitat, And Macroinvertebrate Communities In The Idaho Batholith Ecoregion, Andrew C. Hill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Understanding the composition of lotic communities and the landscape processes and habitat characteristics that shape them is one of the main challenges confronting stream ecologists. In order to better understand the linkages among landscape processes, stream habitat, and biological communities and to understand how accurately our measurements represent important factors influencing biological communities, it is important to test explicit hypotheses regarding these linkages. Increasing our understanding of aquatic communities in a hierarchical context and recognizing how well our measurements represent factors structuring aquatic communities will help managers better evaluate the influence of land management practices on aquatic ecosystems, direct conservation …


Absence Of Predation Eliminates Coexistence: Experience From The Fish-Zooplankton Interface, Z. M. Gilwicz, Wayne A. Wurtsbaugh, E. Szymansk Jan 2010

Absence Of Predation Eliminates Coexistence: Experience From The Fish-Zooplankton Interface, Z. M. Gilwicz, Wayne A. Wurtsbaugh, E. Szymansk

Watershed Sciences Faculty Publications

Examples from fishless aquatic habitats show that competition among zooplankton for resources instigates rapid exclusion of competitively inferior species in the absence of fish predation, and leads to resource monopolization by the superior competitor. This may be a single species or a few clones with large body size: a cladoceran such as Daphnia pulicaria, or a branchiopod such as Artemia franciscana, each building its population to a density far higher than those found in habitats with fish. The example of zooplankton from two different fish-free habitats demonstrates the overpowering force of fish predation by highlighting the consequences of its absence. …


Nutrient Limitation Of Phytoplankton By Nitrogen And Phosphorus: Erosion Of The Phosphorus Paradigm, Wayne A. Wurtsbaugh, William M. Lewis Iii Jan 2009

Nutrient Limitation Of Phytoplankton By Nitrogen And Phosphorus: Erosion Of The Phosphorus Paradigm, Wayne A. Wurtsbaugh, William M. Lewis Iii

Watershed Sciences Faculty Publications

No abstract provided.


Mercury In The Biostrome Community Of The Great Salt Lake, Wayne A. Wurtsbaugh, Caleb Izdepski Jan 2009

Mercury In The Biostrome Community Of The Great Salt Lake, Wayne A. Wurtsbaugh, Caleb Izdepski

Watershed Sciences Faculty Publications

No abstract provided.


Freshwater Responses To Nitrogen And Phosphorus Pollution And A Case Study Of Cutler And Dingle Marsh Wetlands, Wayne A. Wurtsbaugh Jan 2009

Freshwater Responses To Nitrogen And Phosphorus Pollution And A Case Study Of Cutler And Dingle Marsh Wetlands, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

No abstract provided.


Limnological Analyses Of Cutler Reservoir And Dingle Marsh With Respect To Eutrophication, J. D. Abbott, Deb Collins, Colin Cook, Dan Lamarra, Ryan Leonard, Ben Marret, Justin Stout, Gilbert Rowley, Jeremy Rowley, Wayne A. Wurtsbaugh Jan 2009

Limnological Analyses Of Cutler Reservoir And Dingle Marsh With Respect To Eutrophication, J. D. Abbott, Deb Collins, Colin Cook, Dan Lamarra, Ryan Leonard, Ben Marret, Justin Stout, Gilbert Rowley, Jeremy Rowley, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Cutler Reservoir is located in Cache county, Utah and was created for the purposes of irrigation, water storage and flood control. High nutrient loading to Cutler has raised concerns about the health of this system and has resulted in it being listed on the state's 303(d) list of impaired waters. The TMDL plan being drafted for Cutler lists dissolved oxygen and phosphorous as the key issues of concern. The underlying problem created by nutrient loading is eutrophication. If Cutler is to remain as a valuable source of recreation, wildlife habitat, and water for the Cache Valley we must understand the …


Evaluating The Effectiveness Of Grassbed Treatments As Habitat For Juvenile Black Bass In A Drawdown Reservoir, D. R. Ratcliff, Wayne A. Wurtsbaugh, J. Zustak Jan 2009

Evaluating The Effectiveness Of Grassbed Treatments As Habitat For Juvenile Black Bass In A Drawdown Reservoir, D. R. Ratcliff, Wayne A. Wurtsbaugh, J. Zustak

Watershed Sciences Faculty Publications

Many reservoirs in arid regions experience highly variable water levels caused by seasonal inflow fluctuations and designated outflow requirements. At Shasta Lake, California, managers plant cereal-grain grassbeds on exposed drawdown shorelines to increase juvenile fish habitat, localize productivity, and increase invertebrate fish prey. To determine the efficacy of these plantings, the abundance of juvenile black basses Micropterus spp. (20–55 mm standard length) and the amount of periphyton and macroinvertebrate prey were compared among three treatment types: (1) planted grassbeds of cereal barley Hordeum vulgare; (2) artificial rope grassbeds, which eliminated physical deterioration and nutrient release; and (3) nonplanted control sites …


Nutrient Loading And Eutrophication In The Great Salt Lake, Wayne A. Wurtsbaugh Nov 2008

Nutrient Loading And Eutrophication In The Great Salt Lake, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

No abstract provided.


Lakes And Forests As Determinants Of Downstream Nutrient Concentrations In Small Mountain Watersheds, P. D. Brown, Wayne A. Wurtsbaugh, K. Nydick Jan 2008

Lakes And Forests As Determinants Of Downstream Nutrient Concentrations In Small Mountain Watersheds, P. D. Brown, Wayne A. Wurtsbaugh, K. Nydick

Watershed Sciences Faculty Publications

Lakes are dynamic processors of nutrients and may hold an active role in modifying the water chemistry of stream systems. In this study, we examine the influence of lakes and an important terrestrial component—forest cover—on the nutrient levels of stream water in 11 Rocky Mountain (Idaho) watersheds. Water samples were collected from the inflow and outflow of lakes with varying amounts of upstream lakes and forested area during spring runoff and summer base flow. During base flow, mean total nitrogen concentrations at the inflow of final lakes were significantly related to relative upstream lake area, increasing from 34 to 103 …


Spatial Analyses Of Trophic Linkages Between Basins In The Great Salt Lake, Wayne A. Wurtsbaugh, David Naftz, Shane Bradt Jan 2006

Spatial Analyses Of Trophic Linkages Between Basins In The Great Salt Lake, Wayne A. Wurtsbaugh, David Naftz, Shane Bradt

Watershed Sciences Faculty Publications

Although the Great Salt Lake is frequently treated as if it were a single body of water, the natural bays and transportation causeways have divided it into a system of four bays. The bays, however, do not function independently because water, nutrients and other contaminants flow between them. The purpose of our study was to analyze the water quality in three of the bays (Farmington, Bear River and Gilbert), to determine fluxes of nutrients between them, and to determine how this was influencing brine shrimp populations in the lake. Discharge and nutrient concentrations were measured at constrictions separating the three …


Salinity Controls Phytoplankton Response To Nutrient Enrichment In The Great Salt Lake, Utah, Usa, Amy M. Marcarelli, Wayne A. Wurtsbaugh, O. Griset Jan 2006

Salinity Controls Phytoplankton Response To Nutrient Enrichment In The Great Salt Lake, Utah, Usa, Amy M. Marcarelli, Wayne A. Wurtsbaugh, O. Griset

Watershed Sciences Faculty Publications

To examine how salinity and nutrient supply interact to control phytoplankton community composition, nutrient limitation, and dinitrogen (N2) fixation rates in the Great Salt Lake (Utah, USA), we conducted a series of bioassay experiments with plankton from both Gilbert Bay, where salinities are near 160 g·L–1, and Farmington Bay, where salinities range from 10 to 90 g·L–1. Six-day nutrient addition bioassay experiments showed that the extant phyto plankton communities in both bays were limited by nitrogen (N). However, in 28- to 30-day factorial bioassay experiments in which both salinities and nutrient supply were manipulated, phosphorus stimulated chlorophyll a as much …


Continuing Analysis Of Phytoplankton Nutrient Limitation In Farmington Bay And The Great Salt Lake, Wayne A. Wurtsbaugh, Amy M. Marcarelli Apr 2005

Continuing Analysis Of Phytoplankton Nutrient Limitation In Farmington Bay And The Great Salt Lake, Wayne A. Wurtsbaugh, Amy M. Marcarelli

Watershed Sciences Faculty Publications

Farmington Bay is a nutrient-enriched, highly eutrophic embayment of the Great Salt Lake. The highly variable salinity of the bay influences what species of plankton can survive there. Previous analyses suggested that cyanobacteria (blue-green algae) may not be able to survive or fix atmospheric nitrogen at high salinities, thus maintaining the lake in a nitrogen-limited state. To determine the interacting influence of nutrients and salinity on the growth and nitrogen fixation of plankton we performed a 28-day bioassay with water from Farmington and Gilbert Bays in October 2004. We tested the response of the plankton to additions of nitrogen (N) …


Ecological Analysis Of Nutrient, Plankton And Benthic Communities In Farmington Bay And The Great Salt Lake, Utah (2004), Amy M. Marcarelli, Wayne A. Wurtsbaugh Feb 2005

Ecological Analysis Of Nutrient, Plankton And Benthic Communities In Farmington Bay And The Great Salt Lake, Utah (2004), Amy M. Marcarelli, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

In Fall 2004, the Aquatic Ecology Practicum class at Utah State University finished a third year of research on limnological and ecological characteristics of Farmington Bay and Gilbert Bays of the Great Salt Lake. Our previous research has produced interesting findings in Farmington Bay, including hypereutrophy (Marcarelli et a!. 2001), high phosphorus loading into the Bay, overnight water column anoxia linked to high winds (Wurtsbaugh et a!. 2002), potential predator control of brine shrimp, and high levels of hydrogen sulfide in the sediment and deep brine layer (Marcarelli et a!. 2003). These class findings have lead to increased interest in …


Analysis Of Phytoplankton Nutrient Limitation In Farmington Bay And The Great Salt Lake, Wayne A. Wurtsbaugh, Amy M. Marcarelli Jun 2004

Analysis Of Phytoplankton Nutrient Limitation In Farmington Bay And The Great Salt Lake, Wayne A. Wurtsbaugh, Amy M. Marcarelli

Watershed Sciences Faculty Publications

The Great Salt Lake is bordered to the south and east by a growing metropolitan area that contributes high nutrients to Farmington Bay. This large bay is eutrophic, and there is concern that continued increases in effluents from the Salt Lake City area could extend to impact the much larger, and currently less productive, Gilbert Bay. This study focused on determining how nutrient supplies might limit, and therefore control, algal populations in Farmington Bay and Gilbert Bay at different salinities. We tested both short and long-term responses of algal growth using laboratory nutrient addition bioassays in the summer and fall …


Hydrogen Sulfide In Farmington Bay And The Great Salt Lake: A Potential Odor-Causing Agent, Wayne A. Wurtsbaugh, Amy M. Marcarelli Mar 2004

Hydrogen Sulfide In Farmington Bay And The Great Salt Lake: A Potential Odor-Causing Agent, Wayne A. Wurtsbaugh, Amy M. Marcarelli

Watershed Sciences Faculty Publications

Odors from Farmington Bay and/or the Great Salt Lake frequently impact residents of Salt Lake and Davis counties, but the agent causing the problem and the origin of the odor is uncertain. Hydrogen sulfide (H2S) gas is produced in the deeper layers of water in Farmington Bay and Gilbert Bay in the Great Salt Lake, but these deeper waters are generally part of high salinity deep-brine layers that are resistant to wind mixing. Hydrogen sulfide has a "rotten-egg" odor and is a likely component contributing to the "lake stink." The goals of this study were to determine (1) whether wind …


Continuing Studies Of Water Quality In Farmington Bay And The Great Salt Lake, Utah, Amy M. Marcarelli, Wayne A. Wurtsbaugh May 2003

Continuing Studies Of Water Quality In Farmington Bay And The Great Salt Lake, Utah, Amy M. Marcarelli, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

For the past three years, an Aquatic Ecology Practicum class at Utah State University has conducted research examining the limnology of Farmington Bay. In 2000, our class discovered that Farmington Bay could be classified as hypereutrophic, and had significantly higher levels of chlorophyll and phytoplankton than the Great Salt Lake proper (Marcarelli et al. 2001). In 2001, individual student projects identified high phosphorus loading into Farmington Bay from surrounding sewage treatment plants, brine shrimp biomass five times lower than in the Great Salt Lake, and that the water in the bay lost all oxygen on a windy night in October …


Winter Ecology Of Kokanee: Implications For Salmon Management, G. B. Steinhart, Wayne A. Wurtsbaugh Jan 2003

Winter Ecology Of Kokanee: Implications For Salmon Management, G. B. Steinhart, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

We sampled various limnological parameters and measured growth and diet of age-0 kokanee Oncorhynchus nerka (lacustrine sockeye salmon) during two winters in a high-mountain lake of the Sawtooth Valley, Idaho. Although winter has been recognized as an important period for many warmwater fishes and for stream-dwelling salmonids, winter limitations have only recently been studied for coolwater and coldwater species. Ice and snow cover in winter limited light penetration. As a result, chlorophyll-a and zooplankton density were lower in ice-covered periods than during ice-free periods. The weight of stomach contents was often below a maintenance ration, yet the incidence of empty …


Comparative Analysis Of Pollution In Farmington Bay And The Great Salt Lake, Utah, Wayne A. Wurtsbaugh, Amy M. Marcarelli, Cameron Christison, Joel Moore, Donovan Gross, Sophia Bates, Sara Kircher Feb 2002

Comparative Analysis Of Pollution In Farmington Bay And The Great Salt Lake, Utah, Wayne A. Wurtsbaugh, Amy M. Marcarelli, Cameron Christison, Joel Moore, Donovan Gross, Sophia Bates, Sara Kircher

Watershed Sciences Faculty Publications

Farmington Bay covers 94 mi2 (260 km2) in the SW comer of the Great Salt Lake, and is essentially a separate lake because it is enclosed by Antelope Island and a causeway leading to the island from the mainland. The bay has received wastes from the adjoining Salt Lake City metropolitan area for decades. Because of water quality concerns for Farmington 8ay, the Aquatic Ecology Laboratory class at Utah State University studied the bay and a nearby control site (Bridger Bay) in the Great Salt Lake during the fall of 2001. Field sampling and laboratory experiments, as well as other …


Effects Of Epilimnetic Versus Metalimnetic Fertilization On The Phytoplankton And Periphyton Of A Mountain Lake With A Deep Chlorophyll Maxima, Wayne A. Wurtsbaugh, H. P. Gross, Phaedra E. Budy, Chris Luecke Jan 2001

Effects Of Epilimnetic Versus Metalimnetic Fertilization On The Phytoplankton And Periphyton Of A Mountain Lake With A Deep Chlorophyll Maxima, Wayne A. Wurtsbaugh, H. P. Gross, Phaedra E. Budy, Chris Luecke

Watershed Sciences Faculty Publications

Nutrients can load directly to either the epilimnion or metalimnion of lakes via either differential inflow depths of tributaries or intentional fertilization of discrete strata. We evaluated the differential effects of epilimnetic versus metalimnetic nutrient loading using 17-m-deep mesocosms that extended into the deep chlorophyll layer of oligotrophic Pettit Lake in the Sawtooth Mountains of Idaho. Addition of nitrogen plus phosphorus stimulated primary production nearly identically (2.4- to 4-fold on different dates) in both treatments, with the production peaks occurring in the strata where nutrients were added. The metalimnetic fertilization, however, resulted in equal or greater stimulation of chlorophyll a …


Salmonine Consumption And Competition For Endemic Prey Fishes In Bear Lake, Utah-Idaho, J. R. Ruzycki, Wayne A. Wurtsbaugh, Chris Luecke Jan 2001

Salmonine Consumption And Competition For Endemic Prey Fishes In Bear Lake, Utah-Idaho, J. R. Ruzycki, Wayne A. Wurtsbaugh, Chris Luecke

Watershed Sciences Faculty Publications

Two principal sport fish—the indigenous Bonneville cutthroat trout Oncorhynchus clarki utah and the introduced lake trout Salvelinus namaycush—are the dominant piscivores in Bear Lake, a 282-km^2 oligotrophic system. These piscivores rely predominantly on four endemic prey fish species that make up a major portion of the unique Bear Lake fish assemblage. We estimated the annual biomass of pelagic and benthic prey fish by using hydroacoustic and trawling techniques. We also estimated the lakewide abundance of piscivores with a multiple mark–recapture survey and used a bioenergetics model to compare the population-level consumption of prey fish with prey fish production. Prey fish …