Aquaculture and Fisheries Commons^™

Blue Crab Reproductive Output And Phenology In A Changing Climate, Blaise Rohan

Master's Theses

Globally, ecosystems are experiencing rising temperatures due to climate change, with potential consequences for reproductive investment and timing in many species. Blue crabs, Callinectes sapidus, support valuable commercial fisheries throughout the U.S. Atlantic and Gulf coasts, and understanding variation in reproductive output has important management and conservation implications. This study examined two components of blue crab reproduction: (1) reproductive investment across populations spanning multiple latitudes (New York, New Jersey, North Carolina, Mississippi, and Texas), using a space-for-time substitution to assess the effects of varying thermal regimes on fecundity and egg quality, and (2) spawning phenology in North Carolina from …

Assessing The Conservation Needs Of Native Texas Crayfish Species Through Distribution Analysis And Species Distribution Modeling, Elizabeth J. Croft

Biology Theses

Crayfish have essential roles in ecosystems because they are ecosystem engineers and keystone species. However, crayfish species are threatened by degradation and loss of habitats, introduction of invasive species, and high levels of endemism. Texas provides no legal protections for crayfish, despite its large number of species and endemics in the state. The overall goal of this study is to clarify the distributions of native Texas crayfish species using literature records, citizens science, and field sampling data, and highlight species in need of more conservation research. Occurrence records from all collected data were combined to visualize the distributions of species …

Acute Effects Of The Psychoactive Pollutant Fluoxetine On The Antipredator Behavior Of The Gulf Killifish (Fundulus Grandis), Semyra Reus

Honors Theses

Pharmaceutical contaminants are increasingly prevalent in aquatic environments, yet their sublethal effects on ecologically relevant behaviors remain poorly understood, particularly in estuarine systems. Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, are of particular concern due to the conserved role of serotonin in regulating behavior across vertebrates. Here, we investigated how acute exposure to environmentally relevant concentrations of fluoxetine influences anti-predator behavior in Gulf killifish (Fundulus grandis), a key estuarine fish commonly found in saltmarsh habitats. Killifish were exposed to control (0 ng/L), low (17.8 ng/L), and high (596 ng/L) fluoxetine concentrations and subsequently tested in the presence …

Monitoring Biodiversity Growth In An Oyster Reef Restoration: Understanding How Oyster Reef Life Cycle May Impact Biodiversity., Gabriel A. Roses

Theses and Dissertations

Oyster reefs are vital to marine ecosystem health, improving water quality and providing food and habitat for diverse species. We assessed biodiversity changes for a proposed oyster reef restoration site to help guide management, future assessment, and deepen understanding of how oyster reefs function and their ecosystems dynamics.

Feeding Ecology In Coastal Systems, Randi L. Cannon

Graduate Theses and Dissertations (2019 - present)

Oysters (Crassostrea virginica) are critical foundation species in estuaries, providing numerous ecological and economic benefits. However, oyster populations have diminished worldwide. Effective oyster restoration and aquaculture require a mechanistic understanding of the physiological and environmental factors that govern oyster feeding, growth, and resilience under changing coastal conditions. We investigated how oyster ploidy and environmental conditions influenced oyster feeding and investigated how changes in abiotic conditions affected behavioral performance of oyster drills (Stramonita spp.), a key oyster predator. To better understand feeding responses and behaviors of both predator and prey we 1) used in-situ filter feeding assays to determine if feeding …

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

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 …

Just Unmasking Knowledge? A Critical Interpretation Of Fluctuating Jellyfish Populations For A Mass Media Audience, Wrenne R. Grone

Undergraduate Honors Thesis Projects

While podcasts may not be the most popular form of mass media, they are growing in their accessibility and prevalence in educational discourse. My creative work, in the form of a podcast, unmasks scientific knowledge in an untraditional, mass-media form and will use podcast techniques, such as music transitions and storytelling techniques, to maintain engagement. Additionally, my podcast aims to transpose academic knowledge into a comprehensible, interesting form for a non-academic audience. Jellyfish have no brains, no heart, no blood, and no bones and yet, they have survived for millions of years. The goal of my podcast is to educate …

Comparison Of Sampling Methods For Estimation Of Aquatic Insect Diversity And Abundance Across Seasonal Gradients In A Southern U.S. River System, Albert Henry Gasperecz

LSU Master's Theses

Determination of benthic macroinvertebrate assemblage composition plays a vital role in assessment and management of lotic systems throughout the U.S. However, the validity of biomonitoring programs depends on accurate and precise measures of macroinvertebrate abundance, which in turn are dependent on sampling gears and protocols. The goal of this project was to assess how gear selection influences estimates of aquatic insect abundance and diversity, and how this selection can affect biological monitoring practices. I used 4 different gears in 3 southern Mississippi streams to aquatically and terrestrially collect aquatic insects seasonally throughout 2024. I identified and recorded all genera present …

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 …

Retention Time Of Microplastics In The Purple Sea Urchin (Arbacia Punctulata), Alexandra Shore

Honors Theses and Capstones

Marine ecosystems around the world are facing the problem of plastic pollution. Large pieces of plastic eventually degrade into smaller microplastics that are suspended in the water column and sink to the seabed. Sea urchins are exposed to microplastics as they graze on the sea floor and can accidentally consume these pollutants. Sea urchins are ecologically important animals because they physically alter their ecosystem via grazing and are integral part of marine food webs. To better understand how sea urchins interact with microplastics, purple sea urchins were exposed to microfibers and microspheres in a laboratory setting, and the retention time …

Foundations For Trojan-Y Chromosome Development In Sacramento Pikeminnow (Ptychocheilus Grandis): A Novel Strategy For Invasive Species Management In The Eel River, Ca, Raven Mcadams

Cal Poly Humboldt theses and projects

The Sacramento Pikeminnow (Ptychocheilus grandis), an invasive predator in California’s Eel River, contributes to predation pressure on native salmonid populations despite ongoing suppression programs. This study assessed the feasibility of hormonal sex reversal as an initial step toward implementing the Trojan Y Chromosome (TYC) strategy as a novel tool for managing invasive Sacramento Pikeminnow populations in the Eel River, CA. Objectives were to 1) determine the size when gonadal differentiation occurs 2) identify an effective estradiol dosage for producing phenotypic XY females, and 3) identify sex-reversed fish using a sex-specific genetic marker.  Histological examination of juvenile fish was …

Integrating Multi-Method Monitoring To Characterize Seasonal Habitat Use Of Green Sturgeon (Acipenser Medirostris) In Humboldt County, California, Olivia S. Boeberitz

Cal Poly Humboldt theses and projects

Green sturgeon (Acipenser medirostris) are a long-lived, anadromous, iteroparous species that spawns in large West Coast North American rivers but ranges widely in the coastal ocean. For coastal California Native American Tribes, green sturgeon are a vital part of their cultural heritage and traditions, and central to their food security. Two genetically distinct population segments (DPSs) of green sturgeon are recognized in the United States, Canada, and Mexico; the southern DPS is listed as “threatened” under the Endangered Species Act and the northern DPS is considered of “conservation concern.” Although green sturgeon are known to use large estuaries …

The Depuration Of Microplastic Pollution In Aquacultured Indian River Lagoon Oysters, Lee Nguyen

Honors Undergraduate Theses

Plastics are widely used in consumer goods and industrial manufacturing, and their degradation into microplastics (MP, size < 5 mm) has created an emergent environmental pollutant. Plastics readily enter aquatic environments, where they accumulate additional contaminants and bioaccumulate in organisms. While MP contamination in marine ecosystems is well documented, less is known about MP presence in aquacultured shellfish. Depuration, the process of purging contaminants from shellfish, is conducted in sterile seawater without food, which may cause oyster starvation and death. To date, MP depuration has not been examined in the aquacultured eastern oyster (Crassostrea virginica) in published studies. This study had 3 goals: 1) evaluate the effects of algal feed on oyster survival during depuration, 2) determine the effect of algal feed on depuration effectiveness, and 3) investigate the effect of a ten-day depuration on MP concentration in aquacultured C. virginica soft tissue. MP were quantified in oyster tissues, biodeposits, and in industrial algal feed. Tissues were digested using alkaline solutions, manually examined via microscopy, and analyzed using Fourier-Transform Infrared Spectroscopy (FTIR) to investigate MP polymer …

Rate Response Of Curlyleaf Pondweed And Native Plants To Flumioxazin In Minnesota Lakes, Pearl J. Jensen

All Graduate Theses, Dissertations, and Other Capstone Projects

Curlyleaf pondweed (Potamogeton crispus L.) is an invasive aquatic plant present across the United States that causes significant recreational issues, outcompetes native plant species, and depletes water quality. Before senescing in mid-summer, curlyleaf pondweed forms a large number of turions that can lay dormant in the sediment for several years. Typical herbicide management of this species occurs in early spring to target the plant before turion production occurs and while native plants are dormant. Flumioxazin has shown potential in curlyleaf pondweed management in small scale studies, but its effects have not been assessed in operational management. In this study, treatments …

Using Genetic Analysis To Infer Familial Relationships Of Westslope Cutthroat Trout In The Lower Priest River, Idaho, Kolby Emtman

EWU Masters Thesis Collection

The Westslope Cutthroat Trout (Oncorhynchus lewisi) is a native species of salmonid that holds both cultural and ecological significance in the Idaho Panhandle region of the United States. Within this region, the Priest River is a major contributor of migrant Westslope Cutthroat Trout to the Clark Fork Pend Oreille basin. This study aimed to estimate the proportion of juveniles that have at least one migrant parent, illustrate gene flow using juvenile half sibling relationships, and showcase varying levels of spawning success using juvenile full sibling relationships. Sampling of juvenile individuals occurred in 11 tributaries of the Priest River over …

Relationships Between Benthic Macroinvertebrate Communities And Environmental Conditions In Headwater Tributaries Of The Pend Oreille Lake Watershed, Idaho, Devlin Mee

EWU Masters Thesis Collection

Benthic macroinvertebrates are widely used indicators of stream condition, and their communities respond to thermal and land-use conditions in headwater streams. This study characterized macroinvertebrate biomass, community composition, and diversity across forested headwater tributaries of the Pend Oreille lake watershed in northern Idaho, and examined their relationships with summer temperature, land development, and road proximity. Samples from thirteen streams collected in 2024 were identified to genus, measured, and converted to estimated biomass using published length–mass regressions; ten streams had recovered temperature loggers. Because environmental variables were characterized once per stream, all analyses were conducted at the stream level.

Estimated total …

If You Build It, Will They Stay? Fish Communities Continue To Utilize Restored Habitat A Decade Following An Instream Restoration, Alexis L. Vandenberg

Masters Theses

Lotic ecosystems are degraded at an alarming rate due to anthropogenic activities. In order to combat these changes, stream restorations are implemented to improve conditions such as water quality, habitat heterogeneity, and bank stability. However, the impacts of these restorations are often understudied and long-term impacts are unknown. Restorations are typically designed to be ‘fish attractors’; this idea is known as the ‘Field of Dreams hypothesis’ – ‘if you build it, they will come’. This study uses data collected in Kickapoo Creek, Coles County from 2009 to 2015 and again in 2021 and 2022 to assess the long-term impacts of …

Compositional And Functional Shifts In Fish Community Structure In Response To Low-Head Dam Removals, Joshua D. Bruegge

Masters Theses

Low-head dams serve as intermittent barriers to aquatic connectivity and directly alter both upstream and downstream habitats and biotic communities. In 2018 and 2019, two low-head dams in the Vermilion River watershed of eastern Illinois were removed, reconnecting over 1,700 kilometers of upstream habitat within the basin. To determine the impacts of these dam removals, fish community surveys were conducted at 12 fixed sites across three reaches in two rivers from 2012-2022. This study assessed reach-specific temporal responses of the fish community and habitat characteristics. I linked trait expressions within the fish community to abiotic variables using the co-inertia RLQ …

Impact Of Water Level Fluctuations On Fish Populations In Eastern South Dakota Rivers, Benjamin Schall

Electronic Theses and Dissertations

Riverine systems are highly dynamic, and changes in flow conditions can impact the population dynamics of fishes. Increased flows from historical averages in eastern South Dakota rivers have likely impacted fish populations. The goals of this study were to 1) better understand the changes in resource use by Blue Suckers Cycleptus elongatus through retrospective eye lens stable isotope analysis, 2) determine the effects of record flooding in the James River on complex woody habitat and Flathead Catfish Pylodictis olivaris population structure, and 3) assess the influence of river discharge and temperature on Channel Catfish Ictalurus punctatus and Flathead Catfish condition …

Nanoparticle Carriers Enhance The Prophylactic Antiviral Effects Of Dsrna In Vitro And Ex Vivo, Shayne Oberhoffner, Stephanie Dewitte-Orr, Starla Richardson, Leah Haile, Dominique Daniels, Erin Cooper, Aizah Ijaz, Janet Velasquez Perez, Mathilde Peruzzi, Bertrand Collet, Paul Craig, Kristof Jenik

Theses and Dissertations (Comprehensive)

Aquaculture now outpaces traditional capture fisheries as the world population and demand for sustainable protein sources increases. Wild and farmed species are increasingly susceptible to pathogen spread as global temperatures rise and stocking densities increase. Despite the devastating losses experienced by aquaculture due to viral infections, there remain few effective prophylactic antiviral therapeutics. Long double-stranded (ds)RNA is a uniquely viral molecule produced by nearly all viruses during their replication cycle, and its detection by salmonids like rainbow trout (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytsha) leads to the establishment of a defensive antiviral state. Previous in vitro studies demonstrated a …

Coho Salmon (Oncorhynchus Kisutch) Response To Habitat Restoration Through Space And Time: Monitoring Growth, Survival, And Movement In A Restored Habitat Network, Carter Perez Adamson

Cal Poly Humboldt theses and projects

Despite the decline of coho salmon (Oncorhynchus kisutch), Prairie Creek, a tributary of Redwood Creek in northern California, remains a coho salmon stronghold. The restoration of juvenile coho rearing habitat was identified as a recovery objective in this watershed by the National Marine Fisheries Service. Among the restoration projects addressing this objective are an ongoing project on Prairie Creek and its tributary Skunk Cabbage Creek, and a prior effort on Strawberry Creek (a tributary of Redwood Creek’s estuary). Standard monitoring methods for assessing project success have limitations and may be improved by measuring salmon use of restored habitats …

Indigenizing Aquaculture: In Pursuit Of An Integrated Multi-Trophic Aquaculture System For Enhanced Self-Sufficiency In Akaroa Harbour, Aotearoa New Zealand, Cali R. Trainor

Capstone Collection

This study assessed the feasibility of integrating two pre-existing aquaculture activities in Akaroa Harbour, Aotearoa New Zealand into an integrated multi-trophic aquaculture (IMTA) system. The cultivation of giant kelp (Macrocystis pyrifera) presents an opportunity to improve the sustainability of Chinook salmon (Oncorhynchus tshawytscha) farming by introducing alternative food sources for salmon, which can be used to produce fish feed locally, enhancing the self-sufficiency of the community and boosting the holistic efficiency of the system. Macroinvertebrates residing in giant kelp wrack were collected, identified, and quantified to determine if any of the Macrocystis-associated specimens could serve as …

Life History And Distribution Of Two Species Of Cownose Ray, Rhinoptera Bonasus And Rhinoptera Brasiliensis, In Mississippi Coastal Waters, Anna Millender

Master's Theses

Historically, the American Cownose Ray (Rhinoptera bonasus) was considered the only rhinopterid residing in the northern Gulf of Mexico (GOM); however, recent studies have confirmed the presence of the Brazilian Cownose Ray (Rhinoptera brasiliensis) throughout this region. The current study investigated the life history and distribution of both species within Mississippi waters, an area that previously represented a data gap for both species. From April 2016 – July 2025, 193 R. bonasus and 94 R. brasiliensis were analyzed to describe the reproductive biology. Reproductive timing, mating, gestation length, and parturition were similar among species. Although more …

Assessing The Effectiveness Of Extension Services On Aquaculture Development In Ashanti Region, Ghana, Bismark Essel

World Maritime University Dissertations

No abstract provided.

From Larvae To Livelihoods: Examining The Realities Of Black Soldier Fly Farming In Malawi, Emily Herriott

Capstone Collection

Black Soldier Fly (BSF) larvae offer a cost-effective, nutrient-rich alternative to synthetic fertilizers and conventional feed inputs such as soy, fishmeal, and maize bran in sub-Saharan Africa. In Malawi, where smallholder farmers grapple with declining soil fertility, high input prices, chronic food insecurity, and livestock nutritional challenges, BSF farming is emerging as a promising circular agricultural innovation. Despite its technical promise, the social, economic, and ecological realities of BSF adoption remain underexplored.This study investigates the early implementation of BSF farming in Malawi through the Sustainable Livelihoods Framework, focusing on farmer experiences, challenges, and the social and structural processes shaping uptake …

Abundance, Distribution, And Shoaling Of Driftfishes And Allies (Scombriformes: Stromateoidei) In The Pelagic Gulf Of Mexico, Juliet Tretler

All HCAS Student Capstones, Theses, and Dissertations

The suborder Stromateoidei contains 80 species of mesopelagic fishes in five families distributed throughout temperate and tropical seas worldwide, including the Gulf of Mexico (Gulf hereafter). Mesopelagic fishes, especially those that spatially aggregate, serve as important forage items for commercially, recreationally, and ecologically important species of fish, marine mammals, and seabirds. However, knowledge of the ecology and trophic importance of stromateoid fishes in the Gulf is extremely limited. This study provides quantitative information on the species composition, abundance, distribution, and biomass contribution of the stromateoid species to the Gulf deep-pelagic fish assemblage, with comparison to “archetypal” mesopelagic fish families (e.g., …

Trophic Roles And Climate-Driven Vulnerability For Benthic Invertebrates At Artificial Reefs In The Northern Gulf Of Mexico, Amanda Kirkland

LSU New Orleans Theses and Dissertations

Artificial reefs are deployed to enhance marine habitats and fisheries, yet their role in supporting secondary production and their vulnerability to climate stressors remain understudied. This dissertation investigates the trophic ecology and climate sensitivity of benthic invertebrates at artificial reefs in the northern Gulf of Mexico. Chapter 1 assessed reef food webs using stable isotopes from fishes, invertebrates, and primary producers across six reefs and two seasons. Mixing models showed that most fishes rely on benthic reef carbon, while suspension feeders consume plankton and sediment microphytobenthos. Isotopic niche analysis revealed functional diversity and seasonal shifts in δ¹³C and δ³⁴S, though …

Linked Lives In The Riverbed: Integrating Fish Host Dynamics, Community Structure, And Demography For Freshwater Mussel Conservation., Jonathan Patrick Frommeyer

Electronic Theses and Dissertations

Freshwater mussels are long-lived benthic invertebrates that play key roles in nutrient cycling, water filtration, and habitat stability in rivers and streams. Despite their ecological importance, they are among the most imperiled faunal groups in North America, with their persistence increasingly threatened by environmental degradation and disruptions to host–parasite dynamics. This dissertation integrates host ecology, community structure, and demographic modeling to assess population viability and guide conservation priorities for mussel species in Kentucky river systems. The first chapter introduces the ecological context and conservation urgency surrounding freshwater mussels. In particular, emphasizing the need for multi-scale approaches to understand how parasitic …

Insights Gained From Applying Molecular Techniques To Gray Triggerfish (Balistes Capriscus Gmelin, 1789) In The Mexican Caribbean, The Southern And Northwestern Gulf Of Mexico, Geaceli G. Orive

Theses and Dissertations

This study focuses on Balistes capriscus (Gray Triggerfish), a reef-associated species dependent on hard-bottom habitats in the Gulf of Mexico (GOM). Using mitochondrial DNA barcoding and phylogenetic analyses, genetic structure across four sites was assessed: Rio Grande Valley (RGV), Veracruz, Chinchorro Bank, and Xahuayxol. Samples from RGV and Veracruz exhibited limited haplotype diversity, minimal nucleotide divergence, and weak genetic differentiation-patterns consistent with recent population expansion and ongoing connectivity within the GOM. While the study centered on B. capriscus, all individuals from Chinchorro and Xahuayxol unexpectedly grouped with Canthidermis maculata (Spotted Oceanic Triggerfish), suggesting misidentification, cryptic diversity, or taxonomic uncertainty in …