Lake Sturgeon Research Articles

Using Fin Ray Elemental Signatures and Growth Zone Width to Estimate Onset of Sexually Maturity in Lake Sturgeon (Acipenser fulvescens)

Characterizing inter- and intra-population levels of variability in age at sexual maturation for long-lived fishes provides insight into year-class strength and recruitment dynamics, allowing for more effective management practices. Here we analyzed the ontogenetic chronology of pectoral fin ray annuli trace elemental concentration profiles as well as changes in annuli growth in Lake Sturgeon (Acipenser fulvescens) to determine onset of sexual maturity (OSM). Elemental concentrations and growth-zone width were used to build a random forest classification model to discriminate year-specific signatures to before or after OSM from 98 individual fin rays from both sexes across multiple populations and watersheds. The model demonstrated an overall accuracy of 98.8%. Ba was the most important variable related to OSM discrimination success followed by zone width, Pb, Mn, Mg, Zn, Cu, and Sr. Fin ray elemental concentrations began to increase at approximately age 24 (± 4.7) in females and 15 (± 3.1) in males while zone width decreased. This study implies that new applications for fin ray microchemistry are possible and could benefit future fisheries management strategies specifically by adding nonlethal or less invasive sampling techniques for evaluating OSM in sturgeon.

Lake Superior fish community and fisheries, 2001–2022: An era of stability

Lake Superior is the least anthropogenically impacted of the Laurentian Great Lakes ecosystems, yet dramatic changes to the fish community are evident. Previous published works chronicled those changes and the efforts to rehabilitate the fish community through the year 2000. Here, we review through the year 2022, where post-rehabilitation stability was driven by lean lake trout (Salvelinus namaycush namaycush) as the most abundant piscivore in nearshore waters, siscowet lake trout (Salvelinus namaycush siscowet) as the most abundant piscivore in offshore waters, and a healthy, intact assemblage of native prey species, which created ecological redundancies and helped stabilize the food web. Stocking of non-native salmonines was reduced 74%, and populations of Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) were maintained through natural reproduction. Despite reduced stocking, yield from recreational fisheries was stable. Likewise, developments in population modeling led to evaluations and refinement of management strategies that helped create stability for lake trout, lake whitefish (Coregonus clupeaformis), and cisco (Coregonus artedi) fisheries. With lake trout rehabilitation achieved, focus shifted toward rehabilitation of native brook trout (Salvelinus fontinalis), lake sturgeon (Acipenser fulvescens), and walleye (Sander vitreus). Despite continued control efforts, sea lamprey (Petromyzon marinus) abundance increased considerably, and estimates of fish killed by lampreys averaged 2.65 million kg annually. Environmental changes have benefited sea lampreys and fostered thermal habitats more suitable to non-native organisms, posing new challenges for managers and researchers. Nevertheless, the post-rehabilitation stability in the contemporary fish community will help provide resilience to future perturbations in the ecosystem.

Assessing the Efficacy of Three Hatchery Disinfectants for the Inactivation of a Lake Sturgeon Herpesvirus (Family: Alloherpesviridae).

Infectious diseases are a leading cause of losses in the aquaculture industry and conservation programs globally. Simultaneously, infectious diseases pose a substantial risk to fish being hatchery-reared and released into natural habitats for conservation purposes, including the Great Lakes lake sturgeon (Acipenser fulvescens, i.e., GL-LST). Recently, an alloherpesvirus (lake sturgeon herpesvirus 2, i.e., LSHV-2) capable of inducing disease and/or mortality in adult and juvenile GL-LSTs was detected in two adult GL-LST populations. To begin developing disease prevention and/or control methods, in vitro experiments were designed to determine the susceptibility of LSHV-2 to disinfectants commonly used in hatchery and aquaculture facilities (Virkon®-Aquatic: potassium peroxymonosulfate; Ovadine®: polyvinylpyrrolidone iodine complex; and Perox-Aid®: hydrogen peroxide). Cultured LSHV-2 was exposed to each disinfectant at two concentrations (Virkon®-Aquatic: 0.5% and 1%; Ovadine®: 50 and 100 ppm; and Perox-Aid®: 500 and 1000 ppm) in duplicate for durations of 1, 10, and 30 min. Following exposure, the disinfectant was neutralized, and after a 14-day incubation period on a white sturgeon × lake sturgeon hybrid cell line (WSxLS), percent reduction was calculated by comparing the 50% tissue culture infectious doses (TCID50/mL) of the virus with and without disinfectant exposure. When exposed to Perox-Aid®, LSHV-2 percent reduction ranged from 58.7% to 99.5%. When exposed to Ovadine®, the percent reduction ranged from 99.4% to 100%. Lastly, the percent reduction when exposed to Virkon®-Aquatic was 100% for both concentrations and all timepoints. The results herein provide evidence that both Virkon®-Aquatic and Ovadine® are virucidal to LSHV-2 and may represent a means to reduce virus transmission risk under field settings.

Integrated organismal responses induced by projected levels of CO2 and temperature exposures in the early life stages of lake sturgeon.

Atmospheric CO2 and temperature are rising concurrently, and may have profound impacts on the transcriptional, physiological and behavioural responses of aquatic organisms. Further, spring snowmelt may cause transient increases of pCO2 in many freshwater systems. We examined the behavioural, physiological and transcriptomic responses of an ancient fish, the lake sturgeon (Acipenser fulvescens) to projected levels of warming and pCO2 during its most vulnerable period of life, the first year. Specifically, larval fish were raised in either low (16°C) or high (22°C) temperature, and/or low (1000 μatm) or high (2500 μatm) pCO2 in a crossed experimental design over approximately 8 months. Following overwintering, lake sturgeon were exposed to a transient increase in pCO2 of 10,000 μatm, simulating a spring melt based on data in freshwater systems. Transcriptional analyses revealed potential connections to otolith formation and reduced growth in fish exposed to high pCO2 and temperature in combination. Network analyses of differential gene expression revealed different biological processes among the different treatments on the edges of transcriptional networks. Na+/K+-ATPase activity increased in fish not exposed to elevated pCO2 during development, and mRNA abundance of the β subunit was most strongly predictive of enzyme activity. Behavioural assays revealed a decrease in total activity following an acute CO2 exposure. These results demonstrate compensatory and compounding mechanisms of pCO2 and warming dependent on developmental conditions in lake sturgeon. Conserved elements of the cellular stress response across all organisms provide key information for how other freshwater organisms may respond to future climate change.

The spatial extent of Walleye and Lake Sturgeon spawning migrations below a dam in the lower Black Sturgeon River, Lake Superior

AbstractIn the Laurentian Great Lakes, the issue of barrier removal is complicated by the presence of non‐native species below barriers. A fish tracking study was conducted to guide efforts for barrier remediation decisions for the restoration of fish populations with a focus on Walleye (Scander vitreus) and Lake Sturgeon (Acipenser fulvescens) in the Black Sturgeon River, a river system fragmented by a dam which blocks access of fishes to the majority of a large, otherwise barrier‐free watershed. Data from 3 years of spawning migrations (2018–2020) indicated that the Walleye population in Black Bay likely consists of both river (65%) and lake spawners (27%), with the remaining individuals spawning in the bay or river in different years. Walleye and Lake Sturgeon showed consistent differences in the extent to which individuals migrated upstream in the river during the spawning season, despite expectations that both species would spawn at the base of the dam when prevented from further migration. The dam was presumably a barrier to migration for Lake Sturgeon, as nearly all Lake Sturgeon that entered the river migrated to the base of the dam. In contrast, few Walleye entering the river during the spawning season migrated to the dam annually. These findings suggest that Walleye and Lake Sturgeon may not benefit equally, at least in the short term, from barrier remediation or dam removal.

Using seasonal oscillations in fin ray microchemistry to chemically age Lake Sturgeon

AbstractObjectiveNonlethally sampled pectoral fin rays are commonly used as aging structures for Lake Sturgeon Acipenser fulvescens, but they tend to underestimate the true age in older, slow‐growing individuals (age > 14 years). Current aging practices involve counting bands along the structure, which are construed as annuli. Oscillations of certain trace elements corresponding with annuli have been seen across various fish species, with patterns continuing to the marginal edge of hard structures. This study explored the aging of fin rays by using microchemistry patterns in Lake Sturgeon of known age (n = 94; ages 5–21) to determine the potential use of this method as an alternative or supplementary aging technique.MethodsElements were chosen for age determination analysis by examining the relationship between profile minima/maxima and visually interpreted annuli. Fish were assigned ages using three different methods: (1) traditional interpretation (counting annuli along the structure), (2) chemical interpretation (examination of seasonal variations in elemental profiles with visually identified annuli), and (3) a statistical model (multivariate multiple changepoint analysis with finite differencing using raw elemental profiles).ResultMean absolute differences between age estimates and known age were significantly higher for the traditional interpretation method than for the chemical interpretation method. The mean coefficient of variation in estimated age was 11.14% for the traditional interpretation method and 4.04% for the chemical interpretation method. The changepoint model was able to correctly classify age for 100% of the samples within ±1 year in one population (ages 5–8) but could not classify samples from the second population (ages 12–21).ConclusionOur results suggest that chemical aging techniques could provide more reliable age estimates for juvenile and subadult Lake Sturgeon when fin rays are the only aging option. Further work is required to determine the applicability of the model for assigning ages to older fish and for use with different populations and structures.

Occupancy, movement, and behaviour of namew (lake sturgeon Acipenser fulvescens) in an intact river in Canada

Most sturgeon populations are imperilled and living in fragmented rivers. Here, we studied namew (lake sturgeon Acipenser fulvescens), fish important to Ililiwak (Moose Cree Peoples), in the North French River: a free-flowing, intact river in Kit Aski Nahnuun (the Moose Cree Homeland) in northern Ontario, Canada. This study was co-created alongside members of Moose Cree First Nation and used acoustic telemetry to passively track 20 tagged namew over 6 yr (2016-2022). Namew occupied the entire monitored river reach: about 45 km. Namew used 2 overwintering areas and occupied more overall river sections during spring and summer (out of 6 total seasons often used by Ililiwak). We did not detect namew moving upstream or downstream during freeze-up and winter. Generally, namew showed the greatest acceleration and travelled the longest distances during spring and summer, and they occupied shallower water during summer at lower water levels and deepest waters during freeze-up. We found an interaction between season and diurnal period, where namew occupied shallower depths and had higher acceleration at dawn and night relative to morning and afternoon in most seasons; dusk behaviour was variable among seasons. However, this pattern was absent in spring, when namew showed no diurnal pattern in acceleration and were in shallower water during morning and afternoon. Diurnal patterns were less pronounced, but detectable, during ice-affected seasons. This river provides year-round habitat for namew, and our data reveal distinct patterns of namew occupancy, movement, and behaviour in a free-flowing, intact river. Our work is an example of successfully co-creating research that addresses both scientific and community priorities.

Life history characteristics and distribution of lake sturgeon in an unfragmented section of a northern river

Life history characteristics and distribution of lake sturgeon in an unfragmented section of a northern river

Pre‐impoundment fish migrations in the Mobile Basin, Alabama

AbstractAssessing the status of several migratory fishes in the Mobile River Basin, Alabama, has been complicated due to a general lack of historical data on their life history, habitat requirements, and distributions. Whether distributions were restricted by natural or man‐made barriers to migration is difficult to answer because few scientific collections were made before dams were built, and the earliest dams were built at the largest biogeographic barrier in the basin: the geological fall line. Therefore, we used what information was available, including anecdotal information, primarily records from archived newspapers and government reports, to describe the ranges of six migratory species prior to the construction of dams in the Mobile Basin. We describe the complicated history of Alabama Shad Alosa alabamae and show that range declines may have been masked by the stocking of American Shad Alosa sapidissima in the late 19th century. We show that Gulf Sturgeon Acipenser oxyrinchus desotoi probably migrated well above the fall line in the Coosa River, and may have been sympatric with Lake Sturgeon Acipenser fulvescens. We found no records of Alabama Sturgeon Scaphirhynchus suttkusi above the fall line. American Eel Anguilla rostrata migrated above the fall line in every Mobile Basin river before dams were built. Finally, Paddlefish Polyodon spathula may have once occurred above the fall line in at least two rivers, but they persist today in impounded reaches in the coastal plain, unlike some other species. We hope that future work will continue to consider archival sources of information to re‐trace the histories of imperilled species.

Five Species of Wild Freshwater Sport Fish in Wisconsin, USA, Reveal Highly Diverse Viromes.

Studies of marine fish have revealed distant relatives of viruses important to global fish and animal health, but few such studies exist for freshwater fish. To investigate whether freshwater fish also host such viruses, we characterized the viromes of five wild species of freshwater fish in Wisconsin, USA: bluegill (Lepomis macrochirus), brown trout (Salmo trutta), lake sturgeon (Acipenser fulvescens), northern pike (Esox lucius), and walleye (Sander vitreus). We analyzed 103 blood serum samples collected during a state-wide survey from 2016 to 2020 and used a metagenomic approach for virus detection to identify known and previously uncharacterized virus sequences. We then characterized viruses phylogenetically and quantified prevalence, richness, and relative abundance for each virus. Within these viromes, we identified 19 viruses from 11 viral families: Amnoonviridae, Circoviridae, Coronaviridae, Hepadnaviridae, Peribunyaviridae, Picobirnaviridae, Picornaviridae, Matonaviridae, Narnaviridae, Nudnaviridae, and Spinareoviridae, 17 of which were previously undescribed. Among these viruses was the first fish-associated coronavirus from the Gammacoronavirus genus, which was present in 11/15 (73%) of S. vitreus. These results demonstrate that, similar to marine fish, freshwater fish also harbor diverse relatives of viruses important to the health of fish and other animals, although it currently remains unknown what effect, if any, the viruses we identified may have on fish health.

Spawning Habitat Selection and Egg Deposition by Reintroduced Lake Sturgeon in a Tributary to Cayuga Lake, NY

Spawning Habitat Selection and Egg Deposition by Reintroduced Lake Sturgeon in a Tributary to Cayuga Lake, NY

How well do existing surveys track fish community performance measures in the St. Clair-Detroit River System?

The St. Clair-Detroit River System (SCDRS) connects Lake Huron to Lake Erie and provides important habitats for many fishes of economic and ecological importance. Portions of the SCDRS are designated as Great Lakes Areas of Concern and fish production and conservation may be compromised. Efforts to address beneficial use impairments have focused on restoring habitat for native fishes and improving aquatic ecosystem health. Considerable site-specific research and long-term, annual fish surveys have examined responses to habitat improvements. However, there is uncertainty surrounding whether individual studies and surveys can assess (1) population-level benefits of habitat enhancements and (2) whether management objectives are being met. To identify monitoring gaps and inform long-term monitoring program development, we compared outputs from SCDRS fish monitoring surveys (based on discussions with regional agencies) with performance measures specified in management plans (obtained through gray literature searches). Performance measures for harvested species aligned well with outputs of existing surveys. In contrast, at-risk fishes often had objectives and performance measures that reflected knowledge gaps and study needs. Although harvested species were well-monitored relative to specified performance measures, at-risk fishes were less reliably collected by existing surveys, except for lake sturgeon Acipenser fulvescens. Effective evaluation of restoration efforts for at-risk fishes may require additional survey efforts that target species-specific habitat use and life history characteristics.

Comparing the incidence of spontaneous autopolyploidy in wild and hatchery Lake Sturgeon

AbstractObjectiveLiving species of Acipenseriformes, sturgeons and paddlefishes, are characteristically polyploid, having more than two complete sets of chromosomes (>2n). They undergo spontaneous autopolyploidy, an unintentional one and a half times increase in genome size, more frequently than any other order of fish. For Lake Sturgeon Acipenser fulvescens, which are evolutionary octoploids (8n), spontaneous autopolyploidy results in fertile dodecaploid (12n) progeny. When 12n individuals reproduce with octoploids, it is possible that resulting decaploid (10n) offspring will have poor physiological performance and survivorship. Spontaneous autopolyploidy in the wild is very low; however, incidence in fish hatcheries is greater, as seen in other 8n sturgeon species. We investigated this disparity in Lake Sturgeon, predicting to find more dodecaploid individuals in hatchery populations than in the wild.MethodsPloidy was determined using red blood cells from individuals in three hatchery and two wild populations of Lake Sturgeon in Manitoba, Canada (n = 1004). Red blood cell volume was evaluated with a Z2 Coulter counter and used to determine ploidy, based on the average of triplicate measures of the erythrocyte modal nuclei volume (fL). A subsample from each environment type was further examined using blood smear analysis (n = 130) and flow cytometry (n = 27).ResultOne 12n hatchery individual was found, along with significant differences in erythrocyte morphometry between the five populations. Fluctuations in modal nuclei volume were also observed over 169 days of repeated measurement within a single hatchery population.ConclusionThe well‐developed relationship between erythrocyte size and fishes external and physiological environment may explain the variance both between and within populations. These results demonstrate the need for ploidy monitoring in artificial hatcheries, as releasing even a single 12n fish could produce thousands of 10n offspring that, if recruited, would have a detrimental effect on the population fitness.

The long-term effects of water resource development on blood mercury levels and the trophic ecology of Namew (lake sturgeon, Acipenser fulvescens)

The long-term effects of water resource development on blood mercury levels and the trophic ecology of Namew (lake sturgeon, <i>Acipenser fulvescens</i>)

What Lake Sturgeon genetics reveal about population structures

What Lake Sturgeon genetics reveal about population structures

Understanding olfactory and behavioural responses to dietary cues in age-1 lake sturgeon Acipenser fulvescens

Detection of environmental cues is essential for all vertebrates and is typically established by the olfactory epithelium and olfactory sensory neurons (OSNs). In fishes, microvillous and ciliated OSNs are the principal types, typically detecting amino acids and bile salts, respectively. Activation of OSN receptors by specific ligands initiate downstream signal processing often leading to behavioural responses. In this study we used electrophysiological and behavioural techniques to evaluate olfactory detection and behaviour in juvenile lake sturgeon Acipenser fulvescens in response to hatchery- and natural dietary cues. We hypothesized that electro-olfactogram (EOG) and behavioural responses would be dependent on diet type. We predicted that inhibition of the phospholipase C/inositol 1,4,5-triphosphate (PLC/IP3) secondary transduction pathway would reduce EOG responses to dietary cues and, inhibition of the adenylyl cyclase/adenosine 3,5-cyclic monophosphate (cAMP) pathway, would have no effect. Furthermore, we predicted a strong EOG response would be manifested in a change in behaviour. We observed that both the PLC/IP3 and cAMP pathways were significantly involved in the detection of dietary cues. However, EOG responses did not manifest to behavioural responses, although the foraging activity to the hatchery cue was significantly greater compared to the control. Our results support the notion that lake sturgeon raised in a hatchery and fed a commercial pelleted diet may become accustomed to it prior to release into the wild. Further, this study suggests that, in conservation aquaculture settings, lake sturgeon should be exposed to natural dietary cues prior to release as one strategy to promote food recognition.

Vertical Patterns in Lake Sturgeon (Acipenser fulvescens) Larval Drift within Two Rivers Directly Connected to Green Bay, Lake Michigan

Fish larvae in riverine environments often disperse (e.g., drift) from areas of egg deposition at the time of hatch. Several components of drift can be important in terms of survival including timing, distribution in the water column, and body size. The longitudinal and cross-sectional aspects of larval lake sturgeon (Acipenser fulvescens) drift from upstream spawning sites have received considerable study. However, the vertical distribution of larval lake sturgeon in the water column has not been comprehensively evaluated with respect to river size, water depth, the size of larvae in drift over the entire drift period, and the effectiveness of traditional sampling gear (D-frame nets) designed to collect larvae along the river bottom. In 2013, we sampled larval lake sturgeon drifting from upstream spawning sites in the Menominee and Oconto Rivers (Wisconsin, USA) using traditional D-frame nets and custom fabricated sampling nets that vertically partitioned the water column. Drifting larval lake sturgeon were observed from the river bottom to the top of the water column in both systems. Vertical net section was a significant predictor of total larval catch with the highest catch occurring in nets towards the center of the water column but was dependent on net location within the rivers’ cross section and downstream distance from spawning locations. 42% of larvae captured across both rivers were outside of the sampling capability of the traditional D-frame nets (i.e., fish would have drifted over the top). Studies seeking to describe larval production for lake sturgeon, as well as other fish species that exhibit drift in larval dispersal, need to consider a balance between net design and sampling the vertical/cross sectional profiles of rivers. Size-based vertical drift may also have consequences for studies seeking to estimate genetic parameters (e.g., diversity and parentage).

Rewilding the Detroit, Michigan, USA–Windsor, Ontario, Canada Metropolitan Area

Rewilding attempts to increase biodiversity and restore natural ecosystem processes by reducing human influence. Today, there is growing interest in rewilding urban areas. Rewilding of the Detroit, Michigan, USA and Windsor, Ontario, Canada metropolitan area, and its shared natural resource called the Detroit River, has been delineated through the reintroduction of peregrine falcons and osprey, and a return of other sentinel species like bald eagles, lake sturgeon, lake whitefish, walleye, beaver, and river otter. Rewilding has helped showcase the value and benefits of environmental protection and restoration, ecosystem services, habitat rehabilitation and enhancement, and conservation, including social and economic benefits. Improved ecosystem health and rewilding have become a catalyst for re-establishing a reconnection between urban denizens and natural resources through greenways and water trails. The provision of compelling outdoor experiences in nature, in turn, can help foster a personal attachment to the particular place people call home that can help inspire a stewardship ethic.

A New Sturgeon Herpesvirus from Juvenile Lake Sturgeon Acipenser fulvescens Displaying Epithelial Skin Lesions.

Herpesvirus infections of sturgeon pose a potential threat to sturgeon culture efforts worldwide. A new epitheliotropic herpesvirus named Acipenser herpesvirus 3 (AciHV-3) was detected in hatchery-reared Lake Sturgeon Acipenser fulvescens displaying skin lesions in central Canada. The growths were discovered in the fall, reached average prevalence levels of 0.2-40% and eventually regressed. No unusual mortality was observed. The cellular changes within the lesions included epithelial hyperplasia and were reminiscent of other herpesvirus infections. The virus was not evident in lesions examined by electron microscopy. Skin tissue homogenates from symptomatic sturgeon produced atypical cytopathic effects on a primary Lake Sturgeon cell line, and next-generation sequence analysis of the DNA samples revealed the presence of an alloherpesvirus. A new genotyping PCR assay targeting the major capsid protein sequence detected AciHV-3 in symptomatic Lake Sturgeon as well as other apparently healthy sturgeon species. Bayesian inference of phylogeny reconstructed with a concatenation of five alloherpesvirus core proteins revealed a new Alloherpesviridae lineage isomorphic with a new genus. The presence of AciHV-3 homologs in cell lines and sturgeon sequence datasets, low sequence divergence among these homologs and branching patterns within the genotyping phylogeny provide preliminary evidence of an endogenous virus lifestyle established in an ancestral sturgeon.

Comparison of metabolic rate between two genetically distinct populations of lake sturgeon.

Environmental temperatures differ across latitudes in the temperate zone, with relatively lower summer and fall temperatures in the north leading to a shorter growing season prior to winter. As an adaptive response, during early life stages, fish in northern latitudes may grow faster than their conspecifics in southern latitudes, which potentially manifests as different allometric relationships between body mass and metabolic rate. In the present study, we examined if population or year class had an effect on the variation of metabolic rate and metabolic scaling of age-0 lake sturgeon (Acipenser fulvescens) by examining these traits in both a northern (Nelson River) and a southern (Winnipeg River) population. We compiled 6 years of data that used intermittent flow respirometry to measure metabolic rate within the first year of life for developing sturgeon that were raised in the same environment at 16°C. We then used a Bayesian modeling approach to examine the impacts of population and year class on metabolic rate and mass-scaling of metabolic rate. Despite previous reports of genetic differences between populations, our results showed that there were no significant differences in standard metabolic rate, routine metabolic rate, maximum metabolic rate, and metabolic scaling between the two geographically separated populations at a temperature of 16°C. Our analysis implied that the lack of metabolic differences between populations could be due to family effects/parental contribution, or the rearing temperature used in the study. The present research provided insights for conservation and reintroduction strategies for these populations of lake sturgeon, which are endangered or threatened across most of their natural range.