USGS Science⌕ Search

SEARCH · USGS Science

Results for “The Laurentian”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
USGS2016

Transboundary fisheries science: Meeting the challenges of inland fisheries management in the 21st century

Managing inland fisheries in the 21st century presents several obstacles, including the need to view fisheries from multiple spatial and temporal scales, which usually involves populations and resources spanning sociopolitical boundaries. Though collaboration is not new to fisheries science, inland aquatic systems have historically been managed at local scales and present different challenges than in marine or large freshwater systems like the Laurentian Great Lakes. Therefore, we outline a flexible strategy that highlights organization, cooperation, analytics, and implementation as building blocks toward effectively addressing transboundary fisheries issues. Additionally, we discuss the use of Bayesian hierarchical models (within the analytical stage), due to their flexibility in dealing with the variability present in data from multiple scales. With growing recognition of both ecological drivers that span spatial and temporal scales and the subsequent need for collaboration to effectively manage heterogeneous resources, we expect implementation of transboundary approaches to become increasingly critical for effective inland fisheries management.

Fisheries↗
USGS2008

Xenobiotic-induced apoptosis: significance and potential application as a general biomarker of response

The process of apoptosis, often coined programmed cell death, involves cell injury induced by a variety of stimuli including xenobiotics and is morphologically, biochemically, and physiologically distinct from necrosis. Apoptotic death is characterized by cellular changes such as cytoplasm shrinkage, chromatin condensation, and plasma membrane asymmetry. This form of cell suicide is appealing as a general biomarker of response in that it is expressed in multiple cell systems (e.g. immune, neuronal, hepatal, intestinal, dermal, reproductive), is conserved phylogenetically (e.g. fish, rodents, birds, sheep, amphibians, roundworms, plants, humans), is modulated by environmentally relevant levels of chemical contaminants, and indicates a state of stress of the organism. Further, apoptosis is useful as a biomarker as it serves as a molecular control point and hence may provide mechanistic information on xenobiotic stress. Studies reviewed here suggest that apoptosis is a sensitive and early indicator of acute and chronic chemical stress, loss of cellular function and structure, and organismal health. Examples are provided of the application of this methodology in studies of health of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes.

Biomarkers↗
USGS1991

Environmental contaminants and the reproductive success of lake trout in the Great Lakes: An epidemiological approach

Epidemiological criteria were used to examine the influence of environmental contamination on reproductive success of lake trout ( Salvelinus namaycush ,) in the Laurentian Great Lakes. Most of the information was obtained from lake trout eggs collected in southeastern Lake Michigan and reared in the laboratory. Two separate end points that measure reproductive success—egg hatchability and fry survival‐were used in the evaluation. Strong evidence for maternally derived polychlorinated biphenyls causing reduced egg hatchability were observed for the time order, strength of association, and coherence criteria. Equally strong evidence for organic environmental contaminants, also of maternal origin, causing a swim‐up fry mortality syndrome were presented for the strength of association, specificity, replication, and coherence criteria. The epidemiological approach for demonstrating cause‐and‐effect relations was useful because of the difficulty in demonstrating definite proof of causality between specific environmental contaminants and reproductive dysfunction in feral fish.

Journal of Toxicology and Environmental Health↗
USGS2018

Assessing the influence of watershed characteristics on chlorophyll a in waterbodies at global and regional scales

Prediction of primary production of lentic water bodies (i.e., lakes and reservoirs) is valuable to researchers and resource managers alike, but is very rarely done at the global scale. With the development of remote sensing technologies, it is now feasible to gather large amounts of data across the world, including understudied and remote regions. To determine which factors were most important in explaining the variation of chlorophyll a (Chl- a ), an indicator of primary production in water bodies, at global and regional scales, we first developed a geospatial database of 227 water bodies and watersheds with corresponding Chl- a , nutrient, hydrogeomorphic, and climate data. Then we used a generalized additive modeling approach and developed model selection criteria to select models that most parsimoniously related Chl- a to predictor variables for all 227 water bodies and for 51 lakes in the Laurentian Great Lakes region in the data set. Our best global model contained two hydrogeomorphic variables (water body surface area and the ratio of watershed to water body surface area) and a climate variable (average temperature in the warmest model selection criteria to select models that most parsimoniously related Chl- a to predictor variables quarter) and explained ~ 30% of variation in Chl- a . Our regional model contained one hydrogeomorphic variable (flow accumulation) and the same climate variable, but explained substantially more variation (58%). Our results indicate that a regional approach to watershed modeling may be more informative to predicting Chl- a , and that nearly a third of global variability in Chl- a may be explained using hydrogeomorphic and climate variables.

Inland Waters↗
USGS2014

Proterozoic geochronological links between the Farewell, Kilbuck, and Arctic Alaska terranes

New U-Pb igneous and detrital zircon ages reveal that despite being separated by younger orogens, three of Alaska’s terranes that contain Precambrian rocks—Farewell, Kilbuck, and Arctic Alaska—are related. The Farewell and Kilbuck terranes can be linked by felsic magmatism at ca. 850 Ma and by abundant detrital zircons in the Farewell that overlap the ca. 2010–2085 Ma age range of granitoids in the Kilbuck. The Farewell and Arctic Alaska terranes have already been linked via correlative Neoproterozoic to Devonian carbonate platform deposits that share nearly identical faunas of mixed Siberian and Laurentian affinity. New igneous ages strengthen these ties. Specifically, 988, 979, and 979 Ma metafelsites in the Farewell terrane are close in age to a 971 Ma granitic orthogneiss in the Arctic Alaska terrane. Likewise, 852, 850, 845, and 837 Ma granitic orthogneisses, metafelsite, and rhyolite in the Farewell terrane are similar to the reported 874 to 848 Ma age range of metarhyolites in the Arctic Alaska terrane. The Kilbuck and Arctic Alaska terranes have been previously linked on the basis of provenance: detrital zircons from the Carboniferous Nuka Formation in the Arctic Alaska terrane range from 2013 to 2078 Ma, overlapping the age of Kilbuck granitoids. A new 849 Ma age of a Kilbuck granitoid strengthens the proposed connection. Among the other new results from Kilbuck terrane is a 2085 Ma zircon from a granitoid that now stands as the oldest tightly dated rock in Alaska. We conclude that the Kilbuck, Farewell, and Arctic Alaska terranes were not independent entities with unique geologic histories but instead are related pieces of the circum-Arctic tectonic puzzle.

Alaska↗
USGS2024

Defining the hafnium isotopic signature of the Appalachian orogen through analysis of detrital zircons from modern fluvial sediments

Fluvial sediments are the product of erosion, weathering, and transport of bedrock within a well-defined catchment area, and their constituent grains may therefore record valuable information about the lithological and geochemical properties of geologic units within the upstream drainage. Analysis of U-Pb ages and Lu/Hf isotopic values in detrital zircon grains from major rivers in the eastern USA characterizes these parameters within broad areas of the Appalachian orogen. In this study, five modern fluvial sediment samples, collected across ~1500 km and representing 216,000 km2 of total catchment area, reveal that the relative proportions of Mesoproterozoic to Paleozoic U-Pb crystallization ages vary widely across the former Laurentian margin. However, εHft values in the same samples are largely consistent regardless of their geographic location. Mesoproterozoic (Grenville orogen) zircons display a more limited range of εHft values (approximately 0 to +10 εHft units) compared to the more negative, more variable values (-15 to +10) found in grains from the Paleozoic orogenies. When compared to other published modern detrital samples from the Gulf Coastal Plain, Appalachian samples show more similarity to each other and to the Pleistocene of Florida than to those from the Mississippi River mouth, likely because the latter also sources sediments from the Cordillera of western North America. More negative εHft values in Paleozoic zircons may be genetically related to older Mesoproterozoic grains, as they are compatible with the continued isotopic evolution of Lu/Hf derived from the mantle between 1.2 and 2.0 Ga. Hafnium geochemistry in detrital grains may therefore have some utility in discerning sediment provenance between the Appalachians and other regions, and may also provide useful information regarding the nature of crustal generation through time.

Journal of Geology↗
USGS2020

Pheromone pollution from invasive sea lamprey misguides a native confamilial

Animals living in the Anthropocene search for mates facing a barrage of pollutants. Few studies consider pheromones from invasive species as pollution, but their central role in the lives of many animals indicates cross-reaction among historically allopatric relatives has potentially damaging impacts. We hypothesized the sex pheromone of sea lamprey (Petromyzon marinus), an invasive fish in the Laurentian Great Lakes, misguides mate search in native chestnut lamprey (Ichthyomyzon castaneus). In a field test, 100 % of female I. castaneus chose male odourants from P. marinus over conspecifics. Chemical analysis of water in which males were held confirmed both species signal with 3-keto petromyzonol sulfate but revealed higher release rates in P. marinus. Our results indicate sex pheromones from invasive species can be an influential type of pollution and underscore the conservation implications of studies on pheromone evolution.

Current Zoology↗
USGS2025

Leveraging invasive mussel contaminant survey data for stepwise prioritization of chemicals of potential concern in the Great Lakes basin

Historical and ongoing anthropogenic activities coupled with advancements in analytical techniques have led to the detection of large numbers of contaminants in the Laurentian Great Lakes. Consequently, identifying and prioritizing chemicals likely to cause ecological harm represents a challenge for natural resource managers. Previous prioritization efforts have focused on contaminants in sediment, water, and passive samplers, which may not be representative of compounds that bioaccumulate in aquatic organisms. Consequently, this study adopted a stepwise method to prioritize chemicals of potential concern detected in dreissenid mussels from samples collected across the Great Lakes from 2009–2018. The stepwise method considered environmental fate, detection frequency, and exceedance of toxicity quotients based on ecotoxicological effect concentrations. Overall, 153 compounds out of 267 analyzed were detected in dreissenid mussels, 47 of which had water quality effect concentrations, 56 had apical effect concentrations (Tier 1 ECOTOX or apical screening), 17 had nonapical effect concentrations (Tier 2 ECOTOX, Cytotoxic Burst, and ToxCast) and 33 had estimated effect concentrations (quantitative structure-activity relationship, estimated screening, and pharmacological potency). Of the compounds with water quality effect concentrations, nine were designated as high priority, including the herbicide atrazine and five polycyclic aromatic hydrocarbons that were previously identified as potentially hazardous within other matrices. Similar contaminants were identified as high priority in a related study of native unionid mussels in the Great Lakes. A total of 27 compounds were low priority, suggesting that these contaminants do not warrant further action based on this dataset. Overall, these findings will facilitate the development of management strategies to mitigate the effects of contaminants on aquatic organisms within the Great Lakes.

Great Lakes basin↗
USGS2025

Per- and polyfluoroalkyl substances in surface water and sediment in Great Lakes tributaries and relations with watershed attributes

Per- and polyfluoroalkyl substances (PFAS) are chemicals of emerging concern that potentially pose risks to human and environmental health. In May–Oct 2018, sediment and passively collected surface water samples were collected from 62 tributary sites of the Laurentian Great Lakes with site catchments spanning various land cover types. Discrete samples of sediment collected manually and time-integrated surface water samples collected with polar organic chemical integrative samplers (POCIS) were analyzed for 23 and 34 PFAS, respectively. Concentrations of individual PFAS in sediment and surface water varied immensely among sites from below detection to 20,800 ng kg −1 and 247 ng L −1 , respectively. Of all target compounds, PFOS was the most frequently detected in sediment (56 of 62 sites) and had the highest median concentration (132 ng kg −1 ). PFOA, PFHxS, PFOS, PFHpA, and PFNA (full chemical names are listed in online supplementary material Table S2) were detected in all 60 surface water sites, with median estimated concentrations of 5.9, 5.2, 4.6, 3.7, and 1.3 ng L −1 , respectively. Compounds with 8–13 fluorinated carbons comprised a larger proportion of sediment PFAS than compounds with 4–7 fluorinated carbons, whereas compounds with 4–7 fluorinated carbons comprised a greater proportion of PFAS in surface waters. Watershed attributes, including urban land cover, airports per catchment area, and wastewater treatment plants flow percentage were significantly ( p < 0.05) and positively related with PFAS sum concentrations in sediment and (or) surface water. Collectively, these results, albeit with some uncertainty in the estimated concentrations, highlight the relation PFAS occurrence has with human activities and documents widespread low-level PFAS contamination across the Great Lakes basin.

Great Lakes↗
USGS2025

Sea Lamprey control reduction during the COVID-19 pandemic corresponds to rapid increase in Sea Lamprey abundance

The Sea Lamprey Petromyzon marinus control program in the Laurentian Great Lakes is one of the longest-running and most successful invasive species suppression programs in the world. Although several techniques are used to suppress Sea Lamprey, the control program relies heavily on regular application of lampricide to kill stream-dwelling larvae. The COVID-19 pandemic disrupted lampricide application from 2020 to 2022, which provided a unique opportunity to test how Sea Lamprey populations and wound counts on fishes would respond. We evaluated the consequences of decreased control effort at a basin-wide level using standard control program metrics and through a focused analysis of multispecies wounding in Lake Ontario, which experienced the greatest disruption in Sea Lamprey control. The reduction in control effort corresponded to increased basin-wide adult Sea Lamprey abundance but was only weakly associated with Lake Trout Salvelinus namaycush wounding. However, the novel multispecies wounding rate metric calculated for Lake Ontario increased and was consistent with observations by anglers and managers regarding a sharp increase in Sea Lamprey abundance following reduced effort. Ultimately, our research highlights that consistent treatment is critically important for preventing damage stemming from Sea Lamprey and that reductions in suppression could quickly lead to a resurgence in abundance.

Great Lakes↗
USGS1996

Zebra mussel infestation of unionid bivalves (Unionidae) in North America

In 1989, zebra mussels received national attention in North America when they reached densities exceeding 750,000/m2 in a water withdrawal facility along the shore of western Lake Erie of the Laurentian Great Lakes. Although water withdrawal problems caused by zebra mussels have been of immediate concern, ecological impacts attributed to mussels are likely to be the more important long-term issue for surface waters in North America. To date, the epizoic colonization (i.e., infestation) of unionid bivalve mollusks by zebra mussels has caused the most direct and severe ecological impact. Infestation of and resulting impacts caused by zebra mussels on unionids in the Great Lakes began in 1988. By 1990, mortality of unionids was occurring at some locations; by 1991, extant populations of unionids in western Lake Erie were nearly extirpated; by 1992, unionid populations in the southern half of Lake St. Clair were extirpated; by 1993, unionids in widely separated geographic areas of the Great Lakes and the Mississippi River showed high mortality due to mussel infestation. All infested unionid species in the Great Lakes (23) have become infested and exhibited mortality within two to four years after heavy infestation began. Data indicate that mean zebra mussel densities >5,000&ndash;6,000/m 2 and infestation intensities >100-200/unionid in the presence of heavy zebra mussel recruitment results in near total mortality of unionids. At present, all unionid species in rivers, streams, and akes that sympatrically occur with zebra mussels have been infested and, in many locations, negatively impacted by zebra mussels. We do not know the potential consequences of infestation on the 297 unionid species found in North America, but believe zebra mussels pose an immediate threat to the abundance and diversity of unionids.

American Zoologist↗
USGS2020

Advancements towards selective barrier passage by automatic species identification: Applications of deep convolutional neural networks on images of dewatered fish

Invasive species negatively affect enterprises such as fisheries, agriculture, and international trade. In the Laurentian Great Lakes Basin, threats include invasive sea lamprey ( Petromyzon marinus ) and the four major Chinese carps. Barriers have proven to be an effective mechanism for managing invasive species but are detrimental in that they also limit the migration of desirable, native species. Fish passage technologies that selectively pass desirable species while blocking undesirable species are needed. Key to an automated selective barrier passage system is a high precision fish classifier to assign fish to be passed or blocked. Presented is an evaluation of two classifiers developed using images of partially dewatered fish captured from a commercial, high-speed camera array. For a lamprey vs. non-lamprey classification task, an ensemble prediction approach achieved near perfect accuracy on both a validation and test dataset. For a species classification task for 13 species found in the Great Lakes region, an ensemble prediction approach achieved accuracies of 96% and 97% on a validation and test dataset, respectively. Both prediction approaches were based on deep convolutional neural networks constructed using transfer learning and image augmentation. The study provides an important proof-of-concept for the viability in fully automated, selective fish passage systems.

Illinois, Michigan,Ohio↗
USGS2018

Hatchery strain contributions to emerging wild lake trout populations in Lake Huron

Recent assessments indicate the emergence of naturally produced lake trout ( Salvelinus namaycush ) recruitment throughout Lake Huron in the North American Laurentian Great Lakes (>50% of fish <7 years). Because naturally produced fish derived from different stocked hatchery strains are unmarked, managers cannot distinguish strains contributing to natural recruitment. We used 15 microsatellite loci to identify strains of naturally produced lake trout ( N = 1567) collected in assessment fisheries during early (2002–2004) and late (2009–2012) sampling periods. Individuals from 13 American and Canadian hatchery strains ( N = 1143) were genotyped to develop standardized baseline information. Strain contributions were estimated using a Bayesian inferential approach. Deviance information criteria were used to compare models evaluating strain contributions at different spatial and temporal scales. The best performing models were the most complex models, suggesting that hatchery strain contributions to naturally produced lake trout varied spatially among management districts and temporally between time periods. Contributions of Seneca strain lake trout were consistently high across most management districts, with contributions increasing from early to late time periods (estimates ranged from 52% to 94% for the late period across 8 of 9 districts). Strain contributions deviated from expectations based on historical stocking levels, indicating strains differed with respect to survival, reproductive success, and/or dispersal. Knowledge of recruitment levels of strains stocked in different management districts, and how strain-specific recruitment varies temporally, spatially, and as a function of local or regional stocking is important to prioritize strains for future stocking and management of the transition process from primarily hatchery to naturally produced stocks.

Journal of Heredity↗
USGS2021

Invasive sea lamprey detection and characterization using interdigitated electrode (IDE) contact sensor

The ability to monitor invasive sea lamprey (Petromyzon marinus) populations in the Laurentian Great Lakes is critical to protecting the region’s $ 7 billion USD fishing industry and preserving its biodiversity. Monitoring these invaders requires considerable fieldwork and human power, making remote lamprey detection systems attractive for their continuous monitoring capabilities and potential for workload reduction. However, a lack of available methods for detecting sea lamprey hampers development of such systems. Here we present a sensor composed of two exposed planar interdigitated electrodes (IDE) along with a DC measurement system for the detection of lamprey attachment underwater. Measuring voltage instead of impedance, reduces cost and signal processing complexity, making the device more attractive for field deployment. The system is calibrated to a baseline output voltage and deviations from this baseline occur when objects touch the IDE. Validation was done through testing on live adult sea lampreys using video recordings to correlate lamprey attachments to the sensor response. Three response types were identified corresponding to different attachments: sustained, short and sliding-sustained. Sensor response to sustained and sliding-sustained attachments showed a characteristic exponential decay whereas the response due to short attachments was indistinguishable from measurement noise. Lamprey size was found to have a weak linear correlation with both response parameters, positive for the voltage drop and negative for the time constant of voltage drop. A representative circuit for the lamprey-sensor interaction is proposed and simulated using element values calculated from the response parameters. The response of the model shows agreement with experimental data.

Great Lakes↗
USGS2017

Divergent migration within lake sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor

Population structure, distribution, abundance, and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations is an important aspect of the ecology of highly-mobile animals, allowing populations to exploit spatially- or temporally-distributed food and space resources. This study investigated the spatial ecology of lake sturgeon ( Acipenser fulvescens ) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes. Over six years (2011 – 2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 yr battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use. Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assign to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 “contingents” (spatiotemporally segregated subgroups). Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi-independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours did not vary between populations, sexes, body size, or among release locations, which indicated that intrapopulation variability in migratory behaviour is a general feature of the spatial ecology of lake sturgeon in un-fragmented landscapes.

Michigan, Ontario↗
USGS2015

Predicting invasiveness of species in trade: Climate match, trophic guild and fecundity influence establishment and impact of non-native freshwater fishes

Aim Impacts of non-native species have motivated development of risk assessment tools for identifying introduced species likely to become invasive. Here, we develop trait-based models for the establishment and impact stages of freshwater fish invasion, and use them to screen non-native species common in international trade. We also determine which species in the aquarium, biological supply, live bait, live food and water garden trades are likely to become invasive. Results are compared to historical patterns of non-native fish establishment to assess the relative importance over time of pathways in causing invasions. Location Laurentian Great Lakes region. Methods Trait-based classification trees for the establishment and impact stages of invasion were developed from data on freshwater fish species that established or failed to establish in the Great Lakes. Fishes in trade were determined from import data from Canadian and United States regulatory agencies, assigned to specific trades and screened through the developed models. Results Climate match between a species’ native range and the Great Lakes region predicted establishment success with 75–81% accuracy. Trophic guild and fecundity predicted potential harmful impacts of established non-native fishes with 75–83% accuracy. Screening outcomes suggest the water garden trade poses the greatest risk of introducing new invasive species, followed by the live food and aquarium trades. Analysis of historical patterns of introduction pathways demonstrates the increasing importance of these trades relative to other pathways. Comparisons among trades reveal that model predictions parallel historical patterns; all fishes previously introduced from the water garden trade have established. The live bait, biological supply, aquarium and live food trades have also contributed established non-native fishes. Main conclusions Our models predict invasion risk of potential fish invaders to the Great Lakes region and could help managers prioritize efforts among species and pathways to minimize such risk. Similar approaches could be applied to other taxonomic groups and geographic regions.

Diversity and Distributions↗
USGS2016

Divergent life histories of invasive round gobies (Neogobius melanostomus) in Lake Michigan and its tributaries

Round gobies ( Neogobius melanostomus ) have invaded benthic habitats of the Laurentian Great Lakes and connected tributary streams. Although connected, these two systems generally differ in temperature (Great Lakes are typically colder), food availability ( Dreissenid mussels are more prevalent in Great Lakes), and system size and openness. Here, we compare round goby life histories from inshore Lake Michigan and adjacent tributary systems—an uncommon case study of life-history differences between connected systems. Tributary round gobies grew much faster (average length-at-age of 122.3 vs. 65.7 mm for Age 2 + round gobies), appeared to have shorter life spans (maximum observed age of 2 vs. 5) and had lower age-at-50% maturity (1.6 vs. 2.4 years; females only) compared to gobies from Lake Michigan. In addition, tributary gobies had greater fecundity at Ages 1–2 than lake gobies, but had fewer eggs for a given body size prior to the first spawning event of the summer. We were not able to determine the cause of the observed life-history differences. Nonetheless, the observed differences in growth, maturation and longevity were consistent with known effects of water temperature, as well as predictions of life-history theory for animals at invasion fronts exposed to novel environmental conditions. The high degree of phenotypic plasticity in connected populations of this invasive species has implications for our understanding of invasive species impacts in different habitats.

Wisconsin↗
USGS2017

Spawning site fidelity and apparent annual survival of walleye (Sander vitreus) differ between a Lake Huron and Lake Erie tributary

Fidelity to spawning habitats can maximise reproductive success of fish by synchronising movements to sites of previous recruitment. To determine the role of reproductive fidelity in structuring walleye Sander vitreus populations in the Laurentian Great Lakes, we used acoustic telemetry combined with Cormack–Jolly–Seber capture–recapture models to estimate spawning site fidelity and apparent annual survival for the Tittabawassee River in Lake Huron and Maumee River in Lake Erie. Walleye in spawning condition were tagged from the Tittabawassee River in Lake Huron and Maumee River in Lake Erie in 2011–2012. Site fidelity and apparent annual survival were estimated from return of individuals to the stream where tagged. Site fidelity estimates were higher in the Tittabawassee River (95%) than the Maumee River (70%) and were not related to sex or fish length at tagging. Apparent annual survival of walleye tagged in the Tittabawassee did not differ among spawning seasons but was higher for female than male walleye and decreased linearly as fish length increased. Apparent annual survival of walleye tagged in the Maumee River did not differ among spawning seasons but was higher for female walleye than male walleye and increased linearly as fish length increased. Greater fidelity of walleye tagged in the Tittabawassee River than walleye tagged in the Maumee River may be related to the close proximity to the Maumee River of other spawning aggregations and multiple spawning sites in Lake Erie. As spawning site fidelity increases, management actions to conserve population structure require an increasing focus on individual stocks.

Lake Erie, Lake Huron↗