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Articles 1 - 30 of 43
Full-Text Articles in Population Biology
Enhancing Walleye (Ogaa) Recruitment: Evaluating Assisted Reproduction As A Mitigation Strategy, Douglass Keiser
Enhancing Walleye (Ogaa) Recruitment: Evaluating Assisted Reproduction As A Mitigation Strategy, Douglass Keiser
Biology Graduate Theses
Over the past several decades, cold- and cool-water fish populations across the Upper Midwest, including Minnesota and Wisconsin, have shown troubling signs of decline. Among the most affected is the walleye/Ogaa (Sander vitreus), a species deeply embedded in the ecological balance, cultural identity, and economic vitality of the region, and central to the lifeways, treaty-reserved rights, and resource stewardship of Tribal Nations, including Ojibwe communities across the Upper Midwest. Despite ongoing stocking efforts and harvest regulations, many lake systems have experienced persistent declines in natural recruitment, prompting resource agencies to investigate the underlying causes. One such system is …
Emerald Bowfin Amia Ocellicauda Ecology In Three Minnesota Lakes: Abundance, Age Analysis, Diet Composition, And Stable Isotope Food Web, Griffin Blegen
Emerald Bowfin Amia Ocellicauda Ecology In Three Minnesota Lakes: Abundance, Age Analysis, Diet Composition, And Stable Isotope Food Web, Griffin Blegen
Biology Graduate Theses
The Emerald Bowfin Amia ocellicauda is a predatory fish species native to Minnesota that has often been discriminated against. This research expands ecological knowledge of Bowfin in Minnesota and provides population data to guide future management. Bowfin were sampled in the spring of 2024 and 2025 and a multi-census mark–recapture model was used to estimate abundance in three lakes. Estimated populations were 196 individuals in Little Toad Lake (95% CI: 116, 242) or 4.4 fish/littoral ha (95% CI: 2.7,5.7), 657 in Lake Sarah (95% CI: 436, 1014) or 4.2 fish/littoral ha (95% CI: 3.0, 6.7), and 612 in Gun Lake …
Trophic Structure And Mercury Bioaccumulation In Walleye And Yellow Perch In The Upper And Lower Red Lake Basins, Marissa Pribyl
Trophic Structure And Mercury Bioaccumulation In Walleye And Yellow Perch In The Upper And Lower Red Lake Basins, Marissa Pribyl
Biology Graduate Theses
Mercury is a persistent global contaminant that biomagnifies through aquatic food webs, with dietary and environmental factors serving as the primary drivers of accumulation in fishes. Trophic structure and methylmercury dynamics in Walleye (ogaa; Sander vitreus) and Yellow Perch (asaawens; Perca flavescens) were investigated in the Upper and Lower Red Lake basins in Red Lake, Minnesota, during 2024-2025. Diets of Walleye and Yellow Perch were assessed through stomach dissections, and tissue samples from both species were analyzed for total mercury concentrations. Additional analyses included shiners (gigoozens; Notropis spp., Hudsonius spp.) along with a variety of freshwater fish and …
Relationship Between Ratio Of Hybrid Sunfish To Their Parent Species And Latitude, Maxwell Kattner
Relationship Between Ratio Of Hybrid Sunfish To Their Parent Species And Latitude, Maxwell Kattner
Journal of Earth and Life Science
Hybrid sunfish of the Lepomis genus make up a generally small but notable portion of the population of sunfish in Minnesota lakes. Hybrid sunfish play a significant role in freshwater ecosystems across the United States. They are both morphologically and behaviorally distinct in some ways and similar in other ways to their parent species, causing them to both fill and compete with their parent species for niches occupied by multiple Lepomis species. Despite this, the ratio of hybrid sunfish to their parent species has never been properly explored. This study observed if the ratio of hybrid sunfish to their parent …
Effectiveness Of Walleye Stocking In Winter Kill Lakes, Tyler Haus
Effectiveness Of Walleye Stocking In Winter Kill Lakes, Tyler Haus
Journal of Earth and Life Science
Winter kill events, marked by extensive fish mortality due to hypoxic conditions under the ice, are a common phenomenon in shallow eutrophic lakes, especially in the northern lakes in the northern United States. These events can drastically alter fish communities and often result in the elimination of top predators. Though these lakes will typically slowly bounce back to what they were in a couple of years. This study evaluates the effectiveness of walleye, Sander vitreus, stocking in lakes after a winter kill. For this study, four known winter kill lakes that are consistently stocked with walleye were studied. Pre- …
Size Structure Comparison Of Bluegill In Lakes With And Without Special Regulations, Jenna Lawin
Size Structure Comparison Of Bluegill In Lakes With And Without Special Regulations, Jenna Lawin
Journal of Earth and Life Science
Lots of individuals have mixed feelings about special regulations for all sorts of game fish species such as northern pike Esox lucius, crappie Pomoxis spp., sunfish Lepomis spp., and so on. One species commonly sought after by many is bluegill Lepomis macrochirus. Bluegill are often deemed easy to find, catch, and clean. This study looks at three different categories of lakes (all lakes contain bluegill populations). The three categories are lakes with a five sunfish limit, lakes with a ten sunfish limit, and lakes without any special regulations. This study provides valuable insight into the size …
Size Of Age-0 Sander Vitreus Pre And Post Dreissena Polymorpha Infestation On Brainerd And Bemidji Area Lakes, Quady Bernu
Size Of Age-0 Sander Vitreus Pre And Post Dreissena Polymorpha Infestation On Brainerd And Bemidji Area Lakes, Quady Bernu
Journal of Earth and Life Science
Walleye Sander vitreus is the Minnesota state fish and a vital predator fish in lake ecology. Zebra mussels, Dreissena polymorpha were first found in Minnesota inland lakes in the 1980’s. These mussels have had huge impacts on water clarity as well as phytoplankton and zooplankton population levels which affect how age-0 fish feed, especially a low light feeding predator fish like walleye. A study took place on age-0 walleye size and it supported the conclusion that age-0 walleye were negatively impacted by zebra mussels in Minnesota’s large lakes. The goals of this study were to determine how the size of …
Microsatellites Reveal The Population Genetic Structure Of Yellow Perch In Minnesota, Megan Boche
Microsatellites Reveal The Population Genetic Structure Of Yellow Perch In Minnesota, Megan Boche
Journal of Earth and Life Science
When analyzing a population’s genetic makeup, looking at variation of individuals and populations is a crucial factor. The management of yellow perch will be aided by this information particularly in regard to stocking or relocation. Microsatellite loci were used to analyze the genetic population structure of yellow perch Perca flavescens within and among 29 sampling areas throughout Minnesota’s basins. Seven microsatellite DNA loci were evaluated, with heterozygosities ranging from 0.41 to 0.78. The Lower Mississippi basin samples showed higher numbers of alleles per locus and greater expected heterozygosities compared to other basins, with Lake Pepin (PEP) exhibiting the highest average …
Size Structure Of Black Crappie And Bluegill In Northern, Eastern, Western, And Southern Minnesota, Ray Anderson
Size Structure Of Black Crappie And Bluegill In Northern, Eastern, Western, And Southern Minnesota, Ray Anderson
Journal of Earth and Life Science
Fish size structure is an important factor in a fishery population. Panfish such as black crappie Pomoxis nigromaculatus and bluegill Lepomis macrochirus play a major role in the health of fisheries. Five lakes from southern, northern, eastern, and western Minnesota were selected for analysis. Data were collected using standard sampling methods, including gill nets, electrofishing, and fyke nets. Length-frequency distributions were created to assess size structure in each region. Relative abundance was measured using catch per unit effort. Data analysis included a one-way ANOVA to compare Proportional Size Distribution (PSD) values and the distribution of fish sizes among regions. Chi-square …
Comparison Of Hoop Nets To Trap Nets In Sampling Panfish, Jayden R, Alsleben
Comparison Of Hoop Nets To Trap Nets In Sampling Panfish, Jayden R, Alsleben
Journal of Earth and Life Science
Panfish including bluegill Lepomis macrochirus and black crappie Pomoxis nigromaculatus are gamefish species of significance found in Minnesota. Hoop nets and trap nets are two types of gear that can be used to sample these fish. Fisheries managers and anglers alike are interested in the best tactics to capture panfish. The behavior of fish, including bluegill and black crappie, change throughout the sampling season and make it difficult to assume accurate representations. Trap nets have historically been adequate in sampling near shore populations, but questions surrounding the gear have allowed other options to be pursued. The objective of this study …
A Sample Of Fish Communities In Beaver Ponds Of Northern Minnesota, Reed Cumberland, Rose Kuhlmann
A Sample Of Fish Communities In Beaver Ponds Of Northern Minnesota, Reed Cumberland, Rose Kuhlmann
Journal of Earth and Life Science
The North American beaver Castor canadensis is an ecosystem engineer and a keystone species to the environment. Beaver inhabit ponds and construct dams to build ponds that provide habitat for certain fish. Little information is provided on the species of fish that live in beaver ponds. The objective of this study is to sample the fish communities in beaver ponds while comparing the effectiveness of two styles of minnow traps. Twelve beaver ponds were selected in the Bemidji area to be sampled. The quantity and species caught in each style of trap were recorded to compare effectiveness of each trap …
Does Depth Affect Zebra Mussel Length In Scalp Lake?, Zanden Mellen
Does Depth Affect Zebra Mussel Length In Scalp Lake?, Zanden Mellen
Journal of Earth and Life Science
Since its first sighting in 1996, zebra mussels Dreissena polymorpha have been confirmed in hundreds of Minnesota lakes. Not only were they found in lakes, but they are also found in rivers too. With lack of effective treatments to impede their spread, zebra mussels continue to colonize new areas causing ecological as well as economic harm. The objective of this study was to see if there was a relationship between a zebra mussel length and the depth, they are found using shell length (mm) and depth (cm). The comparison of zebra mussel length and depth was done by performing a …
Effect Of Walleye Fry Stocking On Future Gillnet Cpue, Alexander Barker
Effect Of Walleye Fry Stocking On Future Gillnet Cpue, Alexander Barker
Journal of Earth and Life Science
Walleye Sanders vitreus for many states, is a key attractant of anglers from around North America. Due to immense popularity, management efforts have been conducted to maintain Walleye populations, especially in the form of stocking. The purpose of this study is to analyze the effect of Walleye fry stocking on gillnet catch per unit effort (CPUE). A total of 90 lakes were analyzed for this study within three defined regions of Minnesota, 30 from each region. The regions chosen for this study are the Minnesota Department of Natural Resources northern pike Esox lucius regulation regions which consist of the Southern, …
Long Term Trends In Mortality Rates Of A Smallmouth Bass Population, Caleb D. Anderson
Long Term Trends In Mortality Rates Of A Smallmouth Bass Population, Caleb D. Anderson
Journal of Earth and Life Science
Smallmouth bass Micropterus dolomieu are known as a popular sport fish for anglers. When a known smallmouth bass fishery appears to have a dwindling population, it raises questions about the population health. A common indicator of the health of the population is the mortality rate. By comparing mortality, conclusions can be made on whether smallmouth bass are dying at a different rate in the system over time. Therefore, the objective of this study was to see if there had been a significant change in smallmouth bass mortality over a span of thirty years in Round Lake (DOW:010204), Aitkin County, Minnesota. …
Relationship Between Northern Pike And Walleye Cpue In Minnesota Lakes, Simon Oslund
Relationship Between Northern Pike And Walleye Cpue In Minnesota Lakes, Simon Oslund
Journal of Earth and Life Science
Northern pike Esox lucius and walleye Sander vitreus are both top predators in freshwater systems. Due to their predatorial nature, high populations of one species can prohibit populations of the other species from thriving, specifically northern pike foraging on walleye. This information is tracked by the Minnesota Department of Natural Resources through catch per unit effort (CPUE). CPUE data was gathered for all lakes in Beltrami County, Minnesota, and a regression analysis was done to test for a relationship between pike and walleye. It was found that the relationship between northern pike and walleye CPUE was significant (P = 0.02). …
Analysis Of Hematocrit Levels In Walleye Sander Vitreus From Similar Waterbodies, Alyssa Hauser
Analysis Of Hematocrit Levels In Walleye Sander Vitreus From Similar Waterbodies, Alyssa Hauser
Journal of Earth and Life Science
Walleye Sander vitreus are a popular fish among anglers and hold a prominent place in Minnesotan’s identity as their state fish. Because of this, multiple management practices are used to ensure the continued health of their populations within Minnesota waters. In this study, the process of analyzing hematocrit levels was used to determine if the analysis of hematological parameters could be a useful tool in detecting differences in population health. To evaluate this, blood samples were acquired from age-0 and age-1 fish from two similar lakes and run through a hematocrit centrifuge to separate platelets from plasma to read the …
Changes In The Minnesota Northern Pike Population Over The Past Thirty Years, Joey Severin
Changes In The Minnesota Northern Pike Population Over The Past Thirty Years, Joey Severin
Journal of Earth and Life Science
Northern pike Esox lucius are one of the most popular game fish in Minnesota. Many anglers have noticed that northern pike seemed to decrease in size throughout much of this state. Catch per unit of effort (CPUE) drives average weight for northern pike; within lakes, as CPUE goes up average weight decreases. Decreases in size has led the Minnesota Department of Natural Resources (MNDNR) to implement new regulations on northern pike. The MNDNR noticed that not all the state has this same problem with Northern Pike, and has broken down the state into three zones, with different protected slots and …
Comparing The Condition Of Deformed And Non-Deformed Walleyes In Long Lake, Mn, Clayton Beck
Comparing The Condition Of Deformed And Non-Deformed Walleyes In Long Lake, Mn, Clayton Beck
Journal of Earth and Life Science
Walleye Sander vitreus is a popular game fish in Minnesota. Walleye’s have become such a popular game fish for anglers that it has led agencies to raise Walleye in rearing ponds. Farm raised fish can show deformities due to environmental, genetic, nutritional, infectious, and toxic factors. Due to this phenomenon, the purpose of this study was to determine if the condition of the Walleye differed between those with and without deformities in Long Lake, MN. Angling was the method of capture during the months of September 2020 through July 2021. There was no evidence to suggest condition differed between non-deformed …
Effects Of Salt Runoff On Aquatic Macroinvertebrate Colonies, Kendra Fink
Effects Of Salt Runoff On Aquatic Macroinvertebrate Colonies, Kendra Fink
Journal of Earth and Life Science
Aquatic macroinvertebrates bridge the gap in part between primary and secondary consumers, making them ecologically important for most aquatic systems. They are used as biotic indicators for water quality due to their sensitivity to pollutants and may be affected, specifically, by chloride ion concentrations in the water. Water quality can be evaluated by looking at species compositions and their respective tolerance values. To determine long-term effects of road salt on macroinvertebrate colonies, a total of 338 identified macroinvertebrates of 10 families (two generalized to class) at 9 sites were collected from before, after, and between three bridges on Turtle River …
Factors Influencing Aquatic Invertebrate Diversity In Mine Pit Lakes Along The Mesabi Iron Range, Jeremy Laurich
Factors Influencing Aquatic Invertebrate Diversity In Mine Pit Lakes Along The Mesabi Iron Range, Jeremy Laurich
Journal of Earth and Life Science
Restoration of mine pit lakes for recreation is going to be very important for the future of Minnesota’s Mesabi Iron Range area. As many as 250 lakes will need to be restored in the future along this 100-kilometer-long swath of mining country. Information regarding the organisms that currently inhabit these lakes is important for future restorations to be a success. The focus of this study was to identify the types of aquatic invertebrates present in pit lakes and to identify some of the factors that influence their abundance and diversity. During this study, invertebrate samples were taken along the shore …
Abiotic Factors Effect On Summertime Fish Sampling, Kyle Oxley
Abiotic Factors Effect On Summertime Fish Sampling, Kyle Oxley
Journal of Earth and Life Science
Fish surveys are vital in understanding various information about a fishery. Surveys lay the groundwork to how an agency views the status of the fishery, are used to set appropriate regulations, and manage stocking. Understanding which areas of a fishery holds the greatest density of fish is key to achieving the most accurate sample that reflects the fishery. The objective of this study was to track fish densities throughout the summer of 2021 and establish if there is a relationship between high fish density locations and specific water column characteristics. Fish density, temperature, and dissolved oxygen were measured bimonthly at …
Using Northern Pike And Yellow Perch To Attempt A Trophic Cascade, Bryan Sea
Using Northern Pike And Yellow Perch To Attempt A Trophic Cascade, Bryan Sea
Journal of Earth and Life Science
In the midwestern USA, water clarity has decreased in shallow lakes as a result of large populations of Fathead Minnow Pimephales promelas and agriculture that impact the life that depend on shallow habitats, such as waterfowl, fish, and aquatic plants. Northern Pike Esox lucius and Yellow Perch Perca flavescens were stocked in a few lakes in attempt to create a tropic cascade and reduce populations of nuisance Fathead Minnows. Northern Pike were stocked as fry and Yellow Perch were stocked as adults either pre-spawn or post-spawn. Lake managers hypothesized adult Yellow Perch would spawn and the age-0 Perch would feed …
Effects Of Rainbow Trout On Brook Trout Population Size In Tributaries To Lake Superior In Cook County, Minnesota, Craig Tangren
Effects Of Rainbow Trout On Brook Trout Population Size In Tributaries To Lake Superior In Cook County, Minnesota, Craig Tangren
Journal of Earth and Life Science
This study looked at the effects of Rainbow Trout stocking on the size of Brook Trout populations above migratory barriers. Linear mixed effects models were used to determine if there was a relationship between Brook Trout and Rainbow Trout catch rates. Age 1 or older Brook Trout populations were influenced by relative abundance of age 1 or older Rainbow Trout, according to the best supported model based on AIC scores. Population responses varied by stream, ranging along a gradient from high catch rates with a positive relationship to a negative relationship with low relative abundances. Streams with a positive relationship …
Examining Black Bullhead Ameiurus Melas Age And Growth In Shallow Minnesota Lakes, Michael S. Collins, Anna M. Medina
Examining Black Bullhead Ameiurus Melas Age And Growth In Shallow Minnesota Lakes, Michael S. Collins, Anna M. Medina
Journal of Earth and Life Science
Ageing methods, population age structures, and growth trajectories for Black Bullhead Ameiurus melas were evaluated for six populations from shallow lakes divided between two ecoregions in Minnesota, USA. A total of 693 fish were collected in July and August 2018 and measured for total lengths (TL) and weights (g). We collected ageing structures from 320 of these fish. Crosssections of lapillar otoliths (n=191) and pectoral spine structures (n=75) were used to estimate age by two readers in a blind reading procedure. Fish caught ranged in total lengths from ~40 to 350 mm and weighed between 8 and 380 g. Black …
Growth Rate And Hatch Date Of Age-0 Fishes On Leech Lake, Minnesota Before Zebra Mussel Establishment, Kayla Morey, Emily Larson
Growth Rate And Hatch Date Of Age-0 Fishes On Leech Lake, Minnesota Before Zebra Mussel Establishment, Kayla Morey, Emily Larson
Journal of Earth and Life Science
The introduction of an invasive species to an ecosystem is considered a very severe environmental problem. Zebra Mussel veligers Dreissena polymorpha have recently been found in Leech Lake, Minnesota, and are likely going to have a large influence on this ecosystem. Zebra Mussels are filter-feeders that rely on phytoplankton and zooplankton as their main source of energy. A shift in populations of plankton due to Zebra Mussels may affect the growth rates of larval fish. Median hatch dates and growth rates were estimated from four age-0 fish species (Yellow Perch Perca flavescens, Walleye Sander vitreus, Smallmouth Bass Micropterus …
Seasonal Fluctuations Of Zooplankton, Dissolved Oxygen, And Temperature In Lake Bemidji, Minnesota, Cody Coyle
Seasonal Fluctuations Of Zooplankton, Dissolved Oxygen, And Temperature In Lake Bemidji, Minnesota, Cody Coyle
Journal of Earth and Life Science
With the current influx of aquatic invasive species in Minnesota lakes, the status of zooplankton has become vital. Zooplankton are at the base of all food chains in aquatic ecosystems, ecosystems that vary greatly throughout a year’s time. The objectives of this study were to 1) track the location of zooplankton throughout the water column for an entire year, and 2) establish relationships between zooplankton location and specific water column characteristics. Zooplankton, dissolved oxygen, and temperature samples were collected bi-monthly at various depths at the deepest point in the southern basin of Lake Bemidji. Zooplankton were most abundant in the …
Age-0 Walleye Growth Rates Following Spiny Water Flea Bythotrephes Longimanus Invasion, Joseph Amundson
Age-0 Walleye Growth Rates Following Spiny Water Flea Bythotrephes Longimanus Invasion, Joseph Amundson
Journal of Earth and Life Science
Within Voyageurs National Park, spiny water flea Bythotrephes longimanus has reduced Lake Kabetogama and Rainy Lake native zooplankton biomass during summer peak by 40-60%. Subsequently, planktivorous age-0 Yellow Perch Perca flavescens growth has decreased. A possible trophic cascade may influence predatory fish growth rates like that of age-0 Walleye Sander vitreus. Using seine net and electrofishing data, age-0 Walleye growth rates were modeled as a linear function of growing degree days (GDD) and the slope was compared between pre- and post-spiny water flea establishment. Nearby Lake Vermilion, assumed to have been unaffected by spiny water flea until 2015 and …
Redd Habitat Selection For Brook Trout In The Necktie River Bemidji, Mn, William Varela, Zachary Buckley
Redd Habitat Selection For Brook Trout In The Necktie River Bemidji, Mn, William Varela, Zachary Buckley
Journal of Earth and Life Science
The presence of quality suitable habitat is important for the success of naturally reproducing Brook Trout populations. Therefore, measuring redd habitat Brook Trout select for was the focus of this study. Brook Trout redds were observed during the spawning season of 2016. We identified a total of 18 redds in the Necktie River in late October and early November. Specific environmental variables associated with redd selection were measured: velocity, in-stream cover, canopy cover, bank overhang, river width, substrate type and size, temperature, and max-depth. The same environmental variables were measured for 30 randomly selected sites. Redds were distributed in riffles …
Burbot Growth Rates In A Northern Mesotrophic Lake, Samuel J. Peterson
Burbot Growth Rates In A Northern Mesotrophic Lake, Samuel J. Peterson
Journal of Earth and Life Science
Burbot Lota lota has a circumpolar distribution throughout cold-water areas and is the only freshwater member of the family Gadidae. There are currently very few management techniques applied to Burbot throughout their northern extent. Growth is an indicator of fish health, biomass, and habitat quality; therefore, the objective of this study was to determine the growth rate of Burbot in Lake Bemidji. Burbot (n = 45) were collected along three sites on Lake Bemidji for years 2015-2017. Age was determined from sagittal otoliths, the marginal zones of which were opaque from December to May and translucent from June to November. …
Effects Of Catch-And-Release Angling On Egg Densities In Largemouth Bass Nests, Tyler Robinson
Effects Of Catch-And-Release Angling On Egg Densities In Largemouth Bass Nests, Tyler Robinson
Journal of Earth and Life Science
Predation during early life stages of Centrarchidae offspring are a major cause of decreased reproductive success. For five-weeks Largemouth Bass Micropterus salmoides defend their broods from invaders such as Yellow Perch Perca flavescens and Bluegill Lepomis macrochirus. The focus of this study was to determine if predation upon Largemouth Bass broods increased as removal time from the nest via catch-and-release angling increased. Sampling was conducted on the Whitefish Chain, MN from 7 May - 7 June 2016, where a total of 29 nests were located and sampled. Three treatment groups were used; immediate catch-and-release, three-minute, and a seven- minute …