Fox River Research Articles

Significant metabolic alterations in mouse dams exposed to an environmental mixture of polychlorinated biphenyls (PCBs) during gestation and lactation: Insights into PCB and metabolite profiles

Polychlorinated biphenyls (PCBs) and their metabolites are linked to developmental neurotoxicity, but their levels in the gestational and lactational environment remain unexplored. This study investigated the effects of dietary exposure to the Fox River Mixture (FRM) on serum levels of PCBs and their metabolites in female C57BL/6 J mice. Mice were exposed to 0.1, 1.0, or 6.0 mg/kg body weight/day of FRM beginning two weeks before mating and throughout gestation and lactation. Serum samples collected from the dams at weaning were analyzed using gas chromatograph-tandem mass spectrometry and nontarget liquid chromatography-high resolution mass spectrometry. Results showed complex and dose-dependent differences in PCB and metabolite profiles. Untargeted metabolomics revealed alterations in metabolites involved in glucuronidation. Network analysis suggested disturbances in heme and amino acid metabolism associated with higher chlorinated PCBs. These findings suggested that PCBs and metabolites present in the gestational and lactation environment of mice may contribute to developmental neurotoxicity in rodents.

Developmental exposure to the Fox River PCB mixture modulates behavior in juvenile mice

Developmental exposures to PCBs are implicated in the etiology of neurodevelopmental disorders (NDDs). This observation is concerning given the continued presence of PCBs in the human environment and the increasing incidence of NDDs. Previous studies reported that developmental exposure to legacy commercial PCB mixtures (Aroclors) or single PCB congeners found in Aroclors caused NDD-relevant behavioral phenotypes in animal models. However, the PCB congener profile in contemporary human samples is dissimilar to that of the legacy Aroclors, raising the question of whether human-relevant PCB mixtures similarly interfere with normal brain development. To address this question, we assessed the developmental neurotoxicity of the Fox River Mixture (FRM), which was designed to mimic the congener profile identified in fish from the PCB-contaminated Fox River that constitute a primary protein source in the diet of surrounding communities. Adult female C57BL/6 J mouse dams (8–10 weeks old) were exposed to vehicle (peanut oil) or FRM at 0.1, 1.0, or 6.0 mg/kg/d in their diet throughout gestation and lactation, and neurodevelopmental outcomes were assessed in their pups. Ultrasonic vocalizations (USVs) and measures of general development were quantified at postnatal day (P) 7, while performance in the spontaneous alternation task and the 3-chambered social approach/social novelty task was assessed on P35. Triiodothyronine (T3) and thyroxine (T4) were quantified in serum collected from the dams when pups were weaned and from pups on P28 and P35. Developmental exposure to FRM did not alter pup weight or body temperature on P7, but USVs were significantly decreased in litters exposed to FRM at 0.1 or 6.0 mg/kg/d in the maternal diet. FRM also impaired male and female pups’ performance in the social novelty task. Compared to sex-matched vehicles, significantly decreased social novelty was observed in male and female pups in the 0.1 and 6.0 mg/kg/d dose groups. FRM did not alter performance in the spontaneous alternation or social approach tasks. FRM increased serum T3 levels but decreased serum T4 levels in P28 male pups in the 1.0 and 6.0 mg/kg/d dose groups. In P35 female pups and dams, serum T3 levels decreased in the 6.0 mg/kg/d dose group while T4 levels were not altered. Collectively, these findings suggest that FRM interferes with the development of social communication and social novelty, but not memory, supporting the hypothesis that contemporary PCB exposures pose a risk to the developing brain. FRM had sex, age, and dose-dependent effects on serum thyroid hormone levels that overlapped but did not perfectly align with the FRM effects on behavioral outcomes. These observations suggest that changes in thyroid hormone levels are not likely the major factor underlying the behavioral deficits observed in FRM-exposed animals.

Comparison of sediment and water column nutrient processing rates in agricultural streams of contrasting buffer land use

AbstractWatershed nutrient management often focuses on actions that reduce the movement of nitrogen (N) and phosphorus (P) from agricultural lands into streams. One area of management focus is the buffer of land adjacent to streams. Wetlands and forests in this buffer can intercept and retain N and P from the landscape. In addition to directly intercepting agricultural nutrients, natural habitats in the buffer can alter stream geomorphology and influence the in‐stream processing and transformation of N and P to less labile and mobile forms. Here, we assess the influence of buffer land cover on in‐stream processing of N and P. We measured nutrient dynamics in the water column and sediments of agricultural streams in the Fox River and Duck Creek watersheds (WI, USA) during the growing season. In these streams, water column processing was low, possibly due to a lack of primary producers in the water column. Water column P processing was weakly associated with wetland land cover in the buffer, but buffer land cover had no clear effect on inorganic N processing. On the other hand, sediments were almost always a source of inorganic P and a sink for inorganic N. Sediment P release was higher in streams with more agricultural land cover in the buffer. Sediments in streams with agricultural land cover in the buffer also removed more nitrate, even after accounting for the greater availability of nitrate in those streams. The buffer land cover conditions we quantified occupy a very small portion of the overall watershed (100 m wide, for 1 km upstream of the study site) but nevertheless appear to influence in‐stream cycling of N and P. For P management, reducing agricultural land cover in buffers is already a priority due to the ability of wetlands and forests to intercept nutrients, but this study suggests there may be some additional benefit due to changes in in‐stream P processing.

Гидронимы севера Камчатки и их осмысление в устной традиции коряков

The etymology of the names of the largest rivers in the north of Kamchatka: Apuka, Essowejem, and Pakhacha cannot be identified in the context of the Koryak language. These names are apparently a linguistic relic of older tribes who had inhabited the north of Kamchatka before the arrival of the Koryaks. The Koryak language hydronyms have a stable and typical word-formation structure. The model includes the stem base gytgyn ‘lake’ or wejem ‘river’, supplemented by a dependent base according to the rules of left-handed incorporation: Gal’mogytgyn ‘a crooked lake.’ The article considers the hydronyms that directly characterize the natural features of the objects (Yynagytgyn ‘a foggy lake,’ Kujviwejem ‘an icy river’) or refer to a certain kind of trees growing along the river (Tyklawajam ‘a poplar river’). Also considered are metaphorically grounded hydronyms (Upupkin ‘under the nose river’). The analysis covers the hydonyms with warning semantics (Akakujul ‘a terrible swamp stream’, Wajampylka ‘a river where people drown’. The structure of a Koryak hydronym can refer to a particular animal species (Yajolwajam ‘a fox river’) or the hydronym may be rationally motivated (Echgynnywajam ‘white fish river’). It is also possible for hydronyms to have mythological origins. The article presents the fragments of the legends the mythological motifs of which may have provided the basis for the appearance of hydronyms Yil’ewejem ‘the river of the Evrazhka’ or Ev’jojnwajam ‘the river near the place where wolves were driven into a trap.’ In conclusion, hybrid hydronyms used in cartography to nominate tributaries are discussed.

An Epic Battle Against Polluters

Review of Paper Valley: The Fight for the Fox River Cleanup by P. David Allen II and Susan Campbell.

Movement and behavioral states of common carp (Cyprinus carpio) in response to a behavioral deterrent in a navigational lock

BackgroundFreshwater ecosystems are some of the most affected by biological invasions due, in part, to the introduction of invasive carp worldwide. Where carp have become established, management programs often seek to limit further range expansion into new areas by reducing their movement through interconnected rivers and waterways. Lock and dams are important locations for non-physical deterrents, such as carbon dioxide (CO2), to reduce unwanted fish passage without disrupting human use. The purpose of this study was to evaluate the behavioral responses of common carp (Cyprinus carpio) to non-physical deterrents within a navigation structure on the Fox River, Wisconsin. Acoustic telemetry combined with hidden Markov models (HMMs) was used to analyze variation in carp responses to treatments. Outcomes may inform CO2 effectiveness at preventing invasive carp movement through movement pinch-points.MethodsCarbon dioxide (CO2) was recently registered as a pesticide in the United States for use as a deterrent to invasive carp movement. As a part of a multi-component study to test a large-scale CO2 delivery system within a navigation lock, we characterized the influence of elevated CO2 and forced water circulation in the lock chamber on carp movements and behavior. Through time-to-event analyses, we described the responses of acoustic-tagged carp to experimental treatments including (1) CO2 injection in water with forced water circulation, (2) forced water circulation without CO2 and (3) no forced water circulation or CO2. We then used hidden Markov models (HMMs) to define fine-scale carp movement and evaluate the relationships between carp behavioral states and CO2 concentration, forced water circulation, and temperature.ResultsForced water circulation with and without CO2 injection were effective at expelling carp from the lock chamber relative to null treatments where no stimulus was applied. A portion of carp exposed to forced water circulation with CO2 transitioned from an exploratory to an encamped behavioral state with shorter step-lengths and a unimodal distribution in turning angles, resulting in some carp remaining in the lock chamber. Whereas carp exposed to forced water circulation only remained primarily in an exploratory behavioral state, resulting in all carp exiting the lock chamber.ConclusionOur findings illustrate the potential of forced water circulation, alone, as a non-physical deterrent and the efficacy of CO2 injection with forced water circulation in expelling carp from a navigation lock. Results demonstrate how acoustic telemetry and HMMs in an experimental context can describe fish behavior and inform management strategies.

Assessing nutrient and sediment load reduction potential of vegetation by utilizing the nutrient tracking tool at the field and watershed scale in a Great Lakes priority watershed

PurposeNutrient and sediment pollution of surface waters remains a critical challenge for improving water quality. This study takes a user-friendly field-scale tool and assesses its ability to model at both the field and watershed scale within the Fox River Watershed (FRW), Wisconsin, USA, along with assessing how targeted vegetation implementation could attenuate nutrient and sediment exports.MethodsTo assess potential load reductions, the nutrient tracking tool (NTT) was used with a scoring system to identify areas where vegetation mitigation could be implemented within three selected FRW sub-watersheds. A corn soybean rotation, an implementation of a 10-m-vegetated buffer, a full forest conversion, and tiling were modeled and assessed. The corn–soybean results were aggregated and compared to watershed level gauge data in two sub-watersheds. Edge-of-field data was compared to modeled results using multiple parameterization schemes.ResultsThe agricultural areas that scored higher and were untiled showed greater potential nutrient and sediment export reduction (up to 80 to 95%) when vegetation mitigation was implemented in the model. Field-scale results aggregated to the watershed scale showed disparities between modeled and measured phosphorus exports but modeled sediment exports fell within observed gauge data ranges. Field-specific parameter adjustments resulted in more accurate modeled results compared to measured edge-of-field export data but needed further refinement.ConclusionTargeted mitigation using a vegetation-based scoring system with the NTT model was shown to be a helpful tool for predicting nutrient and sediment reductions. Using a field-scale model aggregated to the watershed scale presents tradeoffs regarding processes found beyond the edge of field.

A Hydroelectric Plant\'s Performance Evolution

Abstract: Water's potential energy is used to generate electricity in hydroelectric power plants. It generates clean energy. Water may be utilised for agriculture and other purposes after it has been used to generate power. In 1882, a waterwheel on Wisconsin's Fox River was used to generate electricity for the first time. Early in the twentieth century, hydropower continued to play an important role in the global expansion of electrical service. Hydroelectric power plants range in size from a few hundred kW to thousands of MW.

Dissolved organic matter transformations in a freshwater rivermouth

River-to-lake transitional areas are biogeochemically active ecosystems that can alter the amount and composition of dissolved organic matter (DOM) as it moves through the aquatic continuum. However, few studies have directly measured carbon processing and assessed the carbon budget of freshwater rivermouths. We compiled measurements of dissolved organic carbon (DOC) and DOM in several water column (light and dark) and sediment incubation experiments conducted in the mouth of the Fox river (Fox rivermouth) upstream from Green Bay, Lake Michigan. Despite variation in the direction of DOC fluxes from sediments, we found that the Fox rivermouth was a net sink of DOC where water column DOC mineralization outweighed the release of DOC from sediments at the rivermouth scale. Although we found DOM composition also changed during our experiments, alterations in DOM optical properties were largely independent of the direction of sediment DOC fluxes. We found a consistent decrease in humic-like and fulvic-like terrestrial DOM and a consistent increase in the overall microbial composition of rivermouth DOM during our incubations. Moreover, greater ambient total dissolved phosphorus concentrations were positively associated with the consumption of terrestrial humic-like, microbial protein-like, and more recently derived DOM but had no effect on bulk DOC in the water column. Unexplained variation indicates that other environmental controls and water column processes affect the processing of DOM in this rivermouth. Nonetheless, the Fox rivermouth appears capable of substantial DOM transformation with implications for the composition of DOM entering Lake Michigan.

Conrad Seabaugh & Company: An Inside Look at an Illinois Hinterland Merchant

Conrad Seabaugh & Company: An Inside Look at an Illinois Hinterland Merchant

Biofouling of a unionid mussel by dreissenid mussels in nearshore zones of the Great Lakes.

In North America, native unionid mussels are imperiled due to factors such as habitat degradation, pollution, and invasive species. One of the most substantial threats is that posed by dreissenid mussels, which are invasive mussels that attach to hard substrates including unionid shells and can restrict movement and feeding of unionids. This dreissenid mussel biofouling of unionids varies spatially in large ecosystems, such as the Great Lakes, with some areas having low enough biofouling to form effective refugia where unionid mussels might persist. Here, we measured biofouling on mussels suspended in cages over the growing season (generally first week in June to last week of August) over 3 years in nearshore areas in Lake Erie (2014-2016), Lake Michigan (Grand Traverse Bay, 2015 and Green Bay, 2016), and Lake Huron (2015). Biofouling varied substantially by years within Lake Erie, with increasingly higher biofouling rates each year. Although dreissenid mussels are present throughout these lakes, we observed very low biofouling in Grand Traverse Bay (Lake Michigan) and Saginaw Bay (Lake Huron), with no dreissenid mussels in 8 of 9 sites across these two bays. Sampling in the rivermouth of the Fox River (Wisconsin) and the Maumee River (Ohio) both showed very high biofouling in areas adjacent to the outlet of these tributaries into Green Bay and Maumee Bay (Lake Erie), respectively. These watersheds are dominated by agriculture, and we would expect high growth of primary producers (i.e., mussel food) and primary consumers (unionids and zebra mussels) in these areas compared to the other sampled bays or the open waters of the Great Lakes.

Identification of High‐Occupancy Areas and Movement Dynamics of Age‐0 Lake Sturgeon in the Lower Fox River, Wisconsin

AbstractThe lower Fox River (LFR) is a highly urbanized and fragmented system with a legacy of pollution. Benthic dredging and sediment cleanup combined with capping have been implemented with the goal of remediating the polychlorinated biphenyl contamination and improving the health of resident fish and wildlife populations. The LFR hosts a small population of adult Lake Sturgeon Acipenser fulvescens that spawns at the base of the first barrier, De Pere Dam. Recent research suggests that larval production is limited and no juveniles have been documented residing within the system, although limited sampling has been conducted. The objectives of this study were to describe age‐0 Lake Sturgeon movement patterns, quantify the duration of river residency, and identify areas of congregation in the LFR. To track fish, a total of 38 age‐0 and 1 age‐1 Lake Sturgeon were obtained from nearby wild populations and hatchery settings, implanted with acoustic transmitters, released below De Pere Dam, and actively tracked, daily, for ~40 d (August–October in 2018 and 2019). Sixty‐nine percent of the acoustically tracked age‐0 Lake Sturgeon remained in the LFR for >50% of the study period, and emigration events appear to be related to increases in river discharge. Individuals residing within the LFR tend to congregate within six areas of the LFR encompassing 6% of total river area. The results suggest that suitable habitat exists in the LFR for age‐0 and age‐1 Lake Sturgeon, that discharge may cue downstream movement, and that high‐occupancy areas (likely areas of preferred habitat) are present in the LFR. Long‐term monitoring of larval production, survival, and age‐0/juvenile dynamics will continue to help identify recruitment bottlenecks, improve knowledge of juvenile ecology, and guide future restoration goals.

Associations of concurrent PCB and PBDE serum concentrations with executive functioning in adolescents

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental chemicals that have long half-lives. Humans are exposed to PCBs and PBDEs mainly through diet, and relative to other populations, those who consume sport-caught fish generally have elevated body burdens. Numerous studies have found associations between prenatal exposure to these chemicals and neurodevelopmental deficits, but there are few studies assessing the impact of exposure during adolescence, a period of rapid development of executive functions. We assessed executive functions in adolescents at risk for exposure to PCBs and PBDEs through consumption of fish from the Lower Fox River and other contaminated waters in northeastern Wisconsin. Between 2007 and 2012, a sample of 115 12–18-year-old children was recruited from households in the Green Bay, WI area in which at least one parent held a WI fishing license. We assessed associations of total PCBs and total PBDEs, as well as the predominant individual congeners (PBDE 47 and 153; PCB 138/163, 153 and 180) with performance on four tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB): Intradimensional/Extradimensional Set-Shifting (ID/ED) which assesses cognitive flexibility, Delayed Matching to Sample (DMS) which assesses visual recognition memory, Spatial Working Memory (SWM), and Stockings of Cambridge (SOC) which assess planning and working memory. In addition to the exposure and outcome variables, multivariable regression models included the child's age, sex and IQ score as well as a sex by exposure interaction term. All of the children were non-Hispanic whites and most parents were married, employed, and had at least some college. After adjusting for serum lipids, the GM (GSD) for total PCBs (ng/g) was 30.83 (2.46), and the GM (GSD) for the predominant PCB congeners PCB 138/163, PCB 153, and PCB 180 were 4.60 (2.39), 5.43 (2.37), and 1.01 (2.71), respectively. The GM (GSD) for total PBDEs (ng/g) was 26.82 (3.30), and the GM (GSD) for the predominant PBDE congeners PBDE 47 and PBDE 153 were 16.64 (2.94) and 3.95 (3.43), respectively. For both chemicals, the primary finding of the negative binomial regression analyses was that higher blood serum concentrations were associated with poorer cognitive flexibility as measured on the ID/ED task. In particular, the PCB x sex interaction p-value was 0.08, and stratifying by sex demonstrated that males with higher blood serum total PCB concentrations (β = 2.20, 95% CL: 1.16, 4.16, p = 0.02) took more trials to complete the ID/ED task, while both males and females with higher total PBDE concentrations (β = 1.74, 95% CL: 1.25, 2.42, p = 0.001) took more total trials to complete the task. Higher serum total PCB concentrations were also associated with more errors on the DMS task (β = 1.15, 95% CL: 1.00, 1.31, p < 0.05). These findings suggest that exposure to PCBs or PBDEs during adolescence may be associated with impaired cognitive flexibility and that adolescent PCB exposure may be associated with visual recognition memory deficits.

Native Villages of La Salle's Illinois Country

Native Villages of La Salle's Illinois Country

The disposition of polychlorinated biphenyls (PCBs) differs between germ-free and conventional mice

The disposition of toxicants, such as polychlorinated biphenyls (PCBs), in germ-free (GF) vs. conventional (CV) mice has received little attention to date. Here, we investigate PCB levels in three-month-old female CV and GF mice exposed orally daily for 3 days to 0, 6, or 30 mg/kg body weight of the Fox River Mixture (FRM), an environmental PCB mixture. We euthanized animals 24 h after the final dose. PCB profiles in tissues differed from the FRM profile but were similar in tissues across all 4 PCB exposure groups. PCB levels in CV but not GF mice followed the difference in PCB dose. Importantly, PCB levels were higher in CV than GF mice exposed to the same dose. Hepatic cytochrome P450 enzyme or lipid levels did not explain these trends in PCB tissue levels. Thus, toxicity studies with CV and GF animals need to assess the toxicokinetics of the toxicant investigated. CapsulePCB levels are typically higher in conventional than germ-free mice exposed to the same dose of PCBs.

Benthos of Green Bay, Lake Michigan revisited after 40 years: A temporal update and assessment of environmental associations

Benthos of southern Green Bay, Lake Michigan have not been comprehensively examined since 1978. Since then, invasive species appeared, urbanization intensified, and restoration efforts were implemented, which likely altered the benthic macroinvertebrate community. Further, current benthos are subjected to dynamic factors including eutrophication, sedimentation, and periodic hypoxia. Understanding community responses to these anthropogenic stressors and natural habitat gradients is imperative to preserving biological integrity within Green Bay. Therefore, the objectives of this project were to describe the current macroinvertebrate community, examine changes since 1978, and assess the roles of productivity, substrate type, water depth, and hypoxia in structuring macroinvertebrate communities. Benthos were sampled at 197 stations, including 97 also sampled in 1978 by Markert (1982) and 100 that were added to increase spatial resolution. We collected 93 macroinvertebrate taxa in southern Green Bay with the community dominated by Chironomus and immature tubificid worms. Nonmetric multidimensional scaling (NMDS) ordination distinguished present and historical communities. Although oligochaete worms and chironomids remained dominant over time, Chironomus abundance increased and characterized the present community, whereas benthos were historically more diverse. The magnitude of temporal change varied spatially among zones of Green Bay, with larger differences concentrated in the Middle Bay and the Inner Bay remaining comparable to 1978. Present-day assemblages were most associated with the trophic gradient driven by Green Bay’s southernmost tributary, the Fox River, but also differed with substrate type and had similar structures in areas subjected to frequent hypoxia. Routine monitoring should continue to track changes while accounting for spatial effects.

Featured Cover

The cover image is based on the Original Article Reproductive status of a remnant Lake Sturgeon (Acipenser fulvescens) population: spawning and larval drift in the Lower Fox River, Wisconsin by Stefan Tucker et al., https://doi.org/10.1002/rra.3836. image

Assessment of concentration and distribution of total mercury and polychlorinated biphenyls in Green Bay, Wisconsin, USA

Under the 1987 Great Lakes Water Quality Agreement, the lower Green Bay and Fox River estuary have been labeled as areas of concern due to the contamination of mercury and polychlorinated biphenyls (PCBs) from industrialization. These pollutants pose substantial health and environmental hazards for the Green Bay region. The PCBs reported in this region, including Aroclor 1242, are known to trigger carcinogenic responses in animals and mercury targets the central nervous system and vital organs. Furthermore, these compounds are extremely difficult to remove from the environment once introduced. Extensive remedial actions have been implemented including dredging sediments in the Lower Fox River from DePere to Green Bay. The purpose of this study is to assess the concentration and distribution of Aroclor 1242 and total mercury in the Green Bay region sediments and pore waters and to assess the impact of interventions and the natural rates of change previously found.

Mixed stock analysis of genetic compositions of lake sturgeon (Acipenser fulvescens) mixtures in Lake Michigan: hierarchical spatial heterogeneity and evidence of improving recruitment in Wisconsin spawning populations

Information regarding site occupancy of fish that migrate long distances during nonspawning periods together with estimates of recruitment trends for individual populations can be informative for management, especially when individuals from different spawning populations intermix and are sampled or harvested together. Tendencies for individuals from different populations to preferentially occupy specific regions increases vulnerability to anthropogenic and natural disturbances. Using mixed stock analysis (MSA), we estimated population-specific occupancy of lake sturgeon (Acipenser fulvescens) in open-water and nearshore regions of Lake Michigan across a hierarchy of spatial scales. Open-water mixture composition differed between Lake Michigan’s eastern and western basins. Significant heterogeneity in habitat occupancy was also observed at microgeographic scales throughout open-water regions of Green Bay, indicating nonrandom occupancy to regions proximal to natal streams. Estimates of relative recruitment levels determined from MSA extensions indicated increasing recruitment trends for spawning populations associated with Wisconsin tributaries (Oconto–Peshtigo, Fox, and Menominee rivers). Our lake sturgeon results demonstrate the utility of genetic data for informing management efforts for spatially structured, highly migratory species. Similar analyses could prove beneficial for species with similar characteristics.

Can otolith microchemistry identify the natal origin of larval lake whitefish Coregonus clupeaformis in the waters of Green Bay?

Lake whitefish Coregonus clupeaformis play a key role in the socioeconomics of the Laurentian Great Lakes region and serve as an important conduit of energy among trophic levels. Lake wide declines in adult abundance creates the need for improved understanding of population dynamics, currently hampered by a lack of early life history information and resolution of subpopulation structure. We predicted that otolith microchemistry had the potential to broaden our understanding of lake whitefish ecology by determining the natal origin of larvae at a resolution (e.g., spawning location) unachievable with other techniques. To test this prediction, in 2017 and 2018, recently hatched, pelagically-drifting lake whitefish larvae were collected from the open waters of Green Bay, Lake Michigan and four large tributaries (Menominee, Fox, Oconto and Peshtigo Rivers), where spawning activity has been recently documented. Linear discriminant function analyses conducted at the broadest level of resolution (i.e., river vs. open-water origin) correctly assigned 80.5% and 75.0% of individuals to their natal location in 2017 and 2018, respectively. Reclassification success at a finer resolution (i.e., specific rivers) ranged from 75.9% in 2017 to 42.1% in 2018. We discuss these promising results with respect to underlying variation in geological features, water chemistry and interannual river conditions that eggs and larvae experience during incubation and before prolonged drift.