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Objective: A genetically distinct strain of Walleye Sander vitreus (southern Minnesota strain [SMS]) persists in southern Minnesota lakes despite decades of stocking more easily obtained strains from outside of the region. Because of the regional performance advantage inferred by this persistence, we conducted in situ experiments to compare survival and stocking cost of SMS Walleye fry against those of a frequently stocked northern Minnesota strain (Mississippi headwaters strain [MIS]) to determine whether it is beneficial to expand SMS fry stocking in lieu of historic practices. Methods: We conducted four paired stockings of oxytetracycline‐marked SMS fry and MIS fry into six southern Minnesota lakes and then sampled the fish as fall fingerlings during 2018, 2019, 2021, and 2022. We then used fluorescent microscopy and parentage‐based tagging techniques to discern the stocked strains for comparison of growth and survival. We also obtained production and stocking cost data from agency records to calculate relative stocking costs. Result: By the end of their first summer, SMS Walleye from all but two stockings exhibited higher survival than MIS Walleye. Despite higher initial costs to produce SMS fry, their higher survival to fall fingerlings made the stocking of SMS fry more cost effective than MIS fry stocking. Natural reproduction was also identified in several stocked lakes, most of which consisted of either high or increasing levels of SMS ancestry. Conclusion: A local strain can outperform nonlocal strains at a level that can overcome additional costs of developing a new egg source. In addition, natural reproduction of local‐strain Walleye may reduce or eliminate the need for future stocking. Impact statementWe show that a local Walleye strain can outperform nonlocal strains at a level that can overcome additional costs of developing a new egg source. In addition, higher natural reproduction of the local strain may reduce or eliminate the need for future stocking. [ABSTRACT FROM AUTHOR]

Conservation and management professionals often work across jurisdictional boundaries to identify broad ecological patterns. These collaborations help to protect populations whose distributions span political borders. One common limitation to multijurisdictional collaboration is consistency in data recording and reporting. This limitation can impact genetic research, which relies on data about specific markers in an organism's genome. Incomplete overlap of markers between separate studies can prevent direct comparisons of results. Standardized marker panels can reduce the impact of this issue and provide a common starting place for new research. Genotyping‐in‐thousands (GTSeq) is one approach used to create standardized marker panels for nonmodel organisms. Here, we describe the development, optimization, and early assessments of a new GTSeq panel for use with walleye (Sander vitreus) from the Great Lakes region of North America. High genome‐coverage sequencing conducted using RAD capture provided genotypes for thousands of single nucleotide polymorphisms (SNPs). From these markers, SNP and microhaplotype markers were chosen, which were informative for genetic stock identification (GSI) and kinship analysis. The final GTSeq panel contained 500 markers, including 197 microhaplotypes and 303 SNPs. Leave‐one‐out GSI simulations indicated that GSI accuracy should be greater than 80% in most jurisdictions. The false‐positive rates of parent‐offspring and full‐sibling kinship identification were found to be low. Finally, genotypes could be consistently scored among separate sequencing runs >94% of the time. Results indicate that the GTSeq panel that we developed should perform well for multijurisdictional walleye research throughout the Great Lakes region. [ABSTRACT FROM AUTHOR]

The St. Louis River estuary is a designated area of concern by the U.S. Environmental Protection Agency due to severe environmental degradation. The spatial ecology of Muskellunge Esox masquinongy, an indicator species, is uncertain within the estuary and the large, connected water body, Lake Superior. We collected genetic samples and used passive acoustic telemetry to track 60 adult Muskellunge in the St. Louis River estuary and southwestern Lake Superior for 15 months. Genetic analysis revealed that the river is utilized by two genetic strains—Wisconsin (WI) and Minnesota (MN)—and their hybrids. These genetic strains were previously stocked to restore a nearly extirpated population. Muskellunge tended to move upstream in the spring, downstream and into Lake Superior throughout summer, and to the middle river during fall and winter. Males and females spent significantly more time in the upper and lower portions of the river, respectively. Movements were influenced by strain in that hybrids and the WI strain spent more time in the upper and middle river, and the MN strain spent more time in Lake Superior. A random forest model indicated that Lake Superior use was related to strain (the MN strain made up 80% of individuals using Lake Superior) but not sex or body length, highlighting the importance of understanding strain behavior when stocking different strains. Future research should include investigating Muskellunge habitat use (before, during, and after restoration), tracking juvenile Muskellunge, and connecting telemetry data with mark–recapture and stable isotope data. Our results provide new insight into Muskellunge spatial ecology and genetics that can inform management and restoration efforts within and beyond the Great Lakes. [ABSTRACT FROM AUTHOR]

The Common Carp Cyprinus carpio is an invasive fish whose populations have grown to ecologically damaging levels in the North American Midwest. It has been shown that some shallow nursery habitats contribute disproportionally to population growth of Common Carp in interconnected Midwestern lake systems. The ability of managers to discriminate which shallow basins are producing Common Carp across these systems could increase the efficacy of management practices aimed at disrupting recruitment. We tested whether adult and juvenile Common Carp collected across an interconnected Midwestern lake system could be distinguished based on the concentrations of 11 trace elements measured in their otoliths using laser ablation and high‐resolution inductively coupled plasma mass spectrometry (n = 157). Elemental concentrations in water were also measured with inductively coupled plasma mass spectrometry and found to differ among sites and between habitats, indicating that variation in otolith microchemistry was likely. Aluminum, barium, copper, iron, potassium, lithium, magnesium, sodium, phosphorus, and strontium in the edge region of otoliths differed significantly among Common Carp from all capture sites. Barium, iron, lithium, manganese, and phosphorus differed significantly among juvenile Common Carp from three nursery basins. Aluminum, barium, copper, iron, potassium, lithium, sodium, phosphorus, and strontium were significantly different between nursery and nonnursery habitats. We then investigated the ability to use these elemental otolith edge signatures to differentiate capture locations and distinguish between locations that are active and putative nursery habitats. Quadratic discriminant analysis could classify otoliths to collection site with an accuracy of 54%. Quadratic discriminant analysis had increased accuracy when restricted to juvenile Common Carp (76%) and when classifying Common Carp to nursery and nonnursery habitat types (87%). Further analysis of otolith and water microchemistry indicates temporal instability and suggests a need to collect a multiyear library of otoliths prior to utilization by managers. [ABSTRACT FROM AUTHOR]

Oxytetracycline (OTC) marking and genetic assignment techniques were used to evaluate the contribution and performance of WalleyeSander vitreusfry stocked to accelerate the recovery of a recruitment-overfished population in the Red Lakes, Minnesota. Three stockings of OTC-marked fry from an egg source on the Pike River were conducted at densities of 274 to 358 fry/ha to expedite the recovery of the spawning stock in which the adult female biomass had fallen below 0.5 kg/ha for 10 consecutive years. Two additional stockings of OTC-marked fry from an egg source on a Red Lakes tributary were then conducted at 33 and 87 fry/ha to help quantify natural reproduction as the spawning stock recovered. Subsequent inspection of fish from seine and gill-net samples indicated that Pike River fish composed 50% to 94 % of the stocked year-classes and that the stocked year-classes were three of the strongest in the past 25 years. The Pike River fish survived, grew, and matured at rates similar to the native fish, contributing to an increase in adult female biomass ranging from 2.5 to 8.0 kg/ha. Natural reproduction also increased from a range of 8–120 fry/ha to a range of 199–908 fry/ha, with 49% to 53% Pike River ancestry. For the first 2 years after maturation of the first stocked year-class, however, Pike River ancestry was 13–31 percentage points below what was expected from the relative abundance of Pike River adults in the population. The proportion of Pike River adults present on the tributary spawning runs was also initially below expectations. Both spawning participation and success of Pike River adults increased in successive years, and the stocked fry were judged to have accelerated the recovery of the population to a sustainable and fishable status without the need for additional stocking. Received October 20, 2015; accepted March 9, 2016 Published online July 7, 2016 [ABSTRACT FROM AUTHOR]

Few studies have examined capture and extraction methods for environmental DNA (eDNA) to identify techniques optimal for detection and quantification. In this study, precipitation, centrifugation and filtration eDNA capture methods and six commercially available DNA extraction kits were evaluated for their ability to detect and quantify common carp (Cyprinus carpio) mitochondrial DNA using quantitative PCR in a series of laboratory experiments. Filtration methods yielded the most carp eDNA, and a glass fibre (GF) filter performed better than a similar pore size polycarbonate (PC) filter. Smaller pore sized filters had higher regression slopes of biomass to eDNA, indicating that they were potentially more sensitive to changes in biomass. Comparison of DNA extraction kits showed that the MP Biomedicals FastDNA SPIN Kit yielded the most carp eDNA and was the most sensitive for detection purposes, despite minor inhibition. The MoBio PowerSoil DNA Isolation Kit had the lowest coefficient of variation in extraction efficiency between lake and well water and had no detectable inhibition, making it most suitable for comparisons across aquatic environments. Of the methods tested, we recommend using a 1.5 μm GF filter, followed by extraction with the MP Biomedicals FastDNA SPIN Kit for detection. For quantification of eDNA, filtration through a 0.2-0.6 μm pore size PC filter, followed by extraction with MoBio PowerSoil DNA Isolation Kit was optimal. These results are broadly applicable for laboratory studies on carps and potentially other cyprinids. The recommendations can also be used to inform choice of methodology for field studies. [ABSTRACT FROM AUTHOR]

The Driftless Area in southeastern Minnesota is on the southwestern edge of the native range of Brook TroutSalvelinus fontinalis. It was assumed that native Brook Trout were extirpated from this region in the early 1900s due to degraded stream conditions and stockings of eastern-origin Brook Trout and European Brown TroutSalmo trutta. Our objectives were to examine Brook Trout populations in the region to determine their spatial and genetic distribution and quantify population characteristics. Information on presence or absence of Brook Trout was gathered by electrofishing 174 streams in southeastern Minnesota. Brook Trout were present in 68% of coldwater streams compared with only in 3% in the early 1970s. The increase is likely due to increasing stream discharge throughout the Driftless Area, enabling recolonization or successful establishment of stocked populations. Streams with higher base flow discharge also had higher abundance, larger size at maturity, and larger Brook Trout present. Genetic data on 74 populations were analyzed to characterize genetic variation within populations, assess genetic structure among populations, and determine possible origins. Numerous populations were not associated with known hatchery sources but were primarily composed of geographic groupings that could represent remnant lineages. Although population characteristics were similar among genetic origins, potentially remnant populations should be given conservation priority because they have proven their ability to sustain themselves in this region. Management actions that emphasize maintaining or increasing stream base flows throughout the region will likely enhance remnant Brook Trout populations in the Driftless Area. Received July 25, 2014; accepted March 17, 2015 [ABSTRACT FROM PUBLISHER]

New research techniques and changing Muskellunge Esox masquinongy and Northern Pike E. lucius fisheries have contributed to paradigm shifts in the science and management of these species. A symposium on Muskellunge and Northern Pike biology, ecology and management was held at the American Fisheries Society Annual Meeting in Little Rock, Arkansas, and a panel discussion following the symposium identified several research and management priorities, including spawning habitat identification, habitat and population restoration, genetics, and selective mortality and exploitation. Future Muskellunge and Northern Pike research should focus on quantifying egg and age‐0 survival based on habitat characteristics, rigorously evaluating habitat restoration efforts using statistically sound study designs, describing range‐wide genetic structure of populations, and developing a better understanding of how selective mortality and exploitation can alter population size structure, sex ratios, and life history characteristics. Information and outcomes from the proposed research and management priorities will be critical for conserving and restoring self‐sustaining populations of Muskellunge and Northern Pike. Las nuevas técnicas de investigación y los cambios en las pesquerías de los lucios muskallonga, Esox masquinongy y europeo, E. lucius, han contribuido a modificar paradigmas sobre la ciencia y manejo de estas especies. Se llevó a cabo un simposio sobre biología, ecología y manejo de los lucios muskallonga y europeo en la reunión anual de la Sociedad Americana de Pesquerías, en Little Rock, Arkansas, y en un panel de discusión organizado después del simposio se identificaron diversas prioridades de investigación y manejo que incluyen identificación de hábitats de desove, restauración de hábitats y de poblaciones, genética, mortalidad selectiva y explotación. En el futuro, la investigación sobre los lucios muskallonga y europeo se debe enfocar en cuantificar la supervivencia a nivel de huevos y de edad O; sobre la base de las características del hábitat, evaluar rigurosamente los esfuerzos de restauración de hábitat mediante diseño de sondeos estadísticos, descripción amplia de la estructuración genética de las poblaciones y desarrollar un mejor entendimiento acerca de cómo la mortalidad selectiva y la explotación pueden alterar la estructura de tallas, proporción de sexos y características de la historia de vida de estas especies. Los resultados y la información que se genere tanto de la investigación propuesta como de las prioridades de manejo, serán críticos para la conservación y restauración de las poblaciones auto sostenibles de los lucios muskallonga y europeo. [ABSTRACT FROM AUTHOR]

Tag retention, tag reporting rate, misreading of tags, and other issues are common concerns with traditional tagging methods when marking fish for various stock assessments. These concerns have prompted the development and evaluation of alternative marking techniques by fisheries scientists. Wildlife scientists have overcome these obstacles by using genetic samples in lieu of tagging when studying rare, elusive, and capture-sensitive species. Recent technological advances facilitate similar alternatives for fisheries stock assessment. MuskellungeEsox masquinongypopulations exist at low density and are difficult to sample; the Muskellunge is therefore an appropriate species to use in assessing this tool. We used microsatellite DNA analysis of samples from two connected lakes in north-central Minnesota to estimate adult population size using mark–recapture techniques. In total, 178 unique fish were identified during a trap-net marking period; 59 individuals were identified within an electrofishing resampling period, and 28 of those were recaptures, recognized by their matching genotypes. Based on these data, we obtained a population estimate of 369 adults (95% confidence interval = 269–470). The results of this study demonstrate the utility of genetic markers in place of traditional tagging methods for fish. Received September 24, 2014; accepted December 1, 2014 [ABSTRACT FROM AUTHOR]

Fish stocking, often from multiple source populations, is a common management practice frequently conducted without the means or effort to determine the reproductive contributions of stocked fish. Historically, the Minnesota Department of Natural Resources (MNDNR) has stocked four strains of muskellungeEsox masquinongy, but the contribution of these strains to current populations was unknown. Two strains came from Minnesota lakes, Shoepack Lake and Leech Lake, and the other strains came from Wisconsin and Iowa hatcheries and were of uncertain origin. The MNDNR discontinued stocking the Shoepack strain in the 1980s when that strain displayed poor growth in stocked waters. Managers were concerned that ancestry from this strain might be limiting the genetic potential for muskellunge to attain trophy size in stocked populations. Using 13 microsatellite DNA markers, we determined the ancestry of muskellunge in 10 supplemented native populations and 10 introduced populations. The ancestry from each of the four stocked strains of muskellunge was detected in some populations, but the level of ancestry was unrelated to the amount of stocking of a strain. Ancestry from native populations persisted in six of the supplemented populations despite years of stocking. The potential effects of Shoepack strain ancestry on fish size were limited in most lakes because of its low persistence. All stocked strains reproduced in at least some of the lakes, but some lakes had no evidence of reproduction by any stocked strain. Our results will help MNDNR manage genetic diversity among muskellunge populations and direct efforts toward appropriate actions to improve size structure. This study reinforces how genetic data are often useful for evaluating ancestry in stocked fish populations, whereas stocking histories may be poor indicators of current genetic composition. Received April 6, 2011; accepted May 19, 2012 [ABSTRACT FROM PUBLISHER]

Reintroductions are commonly employed to preserve intraspecific biodiversity in fragmented landscapes. However, reintroduced populations are frequently smaller and more geographically isolated than native populations. Mixing genetically, divergent sources are often proposed to attenuate potentially low genetic diversity in reintroduced populations that may result from small effective population sizes. However, a possible negative tradeoff for mixing sources is outbreeding depression in hybrid offspring. We examined the consequences of mixed-source reintroductions on several fitness surrogates at nine slimy sculpin ( Cottus cognatus) reintroduction sites in south-east Minnesota. We inferred the relative fitness of each crosstype in the reintroduced populations by comparing their growth rate, length, weight, body condition and persistence in reintroduced populations. Pure strain descendents from a single source population persisted in a greater proportion than expected in the reintroduced populations, whereas all other crosstypes occurred in a lesser proportion. Length, weight and growth rate were lower for second-generation intra-population hybrid descendents than for pure strain and first-generation hybrids. In the predominant pure strain, young-of the-year size was significantly greater than any other crosstype. Our results suggested that differences in fitness surrogates among crosstypes were consistent with disrupted co-adapted gene complexes associated with beneficial adaptations in these reintroduced populations. Future reintroductions may be improved by evaluating the potential for local adaptation in source populations or by avoiding the use of mixed sources by default when information on local adaptations or other genetic characteristics is lacking. [ABSTRACT FROM AUTHOR]

Because neither genetic population assignments nor oxytetracycline (OTC) mark identifications are 100% accurate, genetic methods were modeled alone and in combination with OTC mark observations to identify the source of walleyes in a supplemented population and to evaluate the accuracy of OTC mark examination in distinguishing stocked fish that had been treated with OTC from those produced naturally in the lake. Readers examined otoliths from 3,663 fish from two year-classes that were sampled up to 5 years after stocking. A subset of 1,578 of the examined individuals were also assigned to source populations based on genotypes at eight microsatellite loci using baseline genetic data from the stocking source and the recipient population (the measure of genetic divergence [ FST] = 0.07 between populations before stocking). The models indicated that OTC mark observation errors occurred in all samples and that the error rates varied among samples and readers. Model estimates of overall false-negative error rates ranged from 11.4% to 17.2%, and estimates of overall false-positive error rates ranged from 8.9% to 16.7%. Over the ages of walleyes inspected (3 months to age 5), there was neither a systematic increase in mark errors with age nor a decrease in mark intensities; thus, the OTC marks present at 3 months appeared to be permanent. Any true mark absence was due to inefficient OTC immersion treatment or the loss of a successfully applied mark before the first sample was inspected as fingerlings. The presence of both false positives and false negatives in all samples indicates that mark detection error did consistently contribute to the overall mark error rates. Thus, changes in quality control are justified for both OTC immersion treatment and mark detection procedures. [ABSTRACT FROM AUTHOR]

The effects of stocked fish on native populations of the same species are poorly understood. During the 1960s-1980s, the Minnesota Department of Natural Resources (MNDNR) stocked muskellunge derived from Shoepack Lake in the Hudson Bay drainage of northern Minnesota into Moose Lake in the Upper Mississippi River drainage. In the mid-1980s, the MNDNR recognized that stocked Shoepack Lake-strain fish (hereafter, Shoepack strain) were not attaining large sizes, and sources were switched statewide; subsequently, muskellunge from a Wisconsin hatchery were stocked once into Moose Lake. We used 14 microsatellite DNA markers to estimate the genetic contribution by each source population to muskellunge sampled in four different years from 1981 to 2004, and we evaluated the effects of Shoepack-strain ancestry on fish size. Two samples in the 1980s had mostly fish with a single ancestry; thus, these fish were probably Shoepack-strain fish stocked a few years earlier or native fish. By 2004, when most fish would have been naturally produced in the lake, contributions from all three source populations were detected, including admixed individuals from crosses among all ancestral sources. The estimated ancestry by source was 52% native Moose Lake ancestry, 29% Wisconsin strain, and 19% Shoepack strain, with 24% of the individuals having pure Moose Lake ancestry. Fish without Shoepack-strain ancestry had a greater median length than did those with Shoepack-strain ancestry and had a greater proportion of legal-sized individuals (total length ≥ 1,016 mm) in the population. In contrast, Moose Lake and Wisconsin-strain descendents were common among all sizes of fish. Management options include doing nothing, accepting that extensive introgression has already occurred, or manipulating the population by either stocking to dilute Shoepack-strain ancestry or genetic screening to purge the population of Shoepack-strain ancestry. [ABSTRACT FROM AUTHOR]

Species-specific microsatellite DNA markers were used to identify hybrids of black crappies Pomoxis nigromaculatus and white crappies P. annularis and to determine the effect of hybridization on crappie growth. Specifically, we determined the contribution of hybrids to the skew in length frequency distributions that is frequently observed within year-classes of sympatric crappie populations and the resulting upward bias on growth estimates for the two species. Hybridization was found throughout most southern Minnesota Fakes that contained both species, but the frequency of hybrids was low in our length-stratified subsamples (mean frequency of first-generation [F1] hybrids among all lakes and year-classes = 3.2%; mean frequency of advanced-generation [Fx] hybrids = 1.4%). Among the 22 study lakes, only 2 contained no hybrids (based on polymerase chain reaction amplification of microsatellite loci). The F1 hybrids were disproportionately classified as black crappies under a Minnesota Department of Natural Resources (MNDNR) classification system that only allowed assignment of crappies to the two parental species. In one lake sampled over multiple years, we found F1 hybrids in only 5 of 14 year-classes of MNDNR-classified black crappies and in 4 of 11 year-classes of MNDNR-classified white crappies, indicating annual variation in the prevalence of hybridization. Consistent with their faster growth and tendency to be classified as black crappies, F1 hybrids accounted for 82% of all statistical outliers in length distributions of MNDNR-classified black crappie age-classes and 33% of the infrequent outliers in MNDNR-classified white crappie age-classes. The presence of F1 hybrids in our subsamples produced an upward bias in back-calculated length estimates for black crappies but had nonsignificant effects on white crappie length estimates. The effects of hybridization should be taken into account when estimating growth in crappie species from sympatric populations. [ABSTRACT FROM AUTHOR]

The genetic relationships among 337 northern pike (Esox lucius) collected from the coastal zone of the central Baltic region and the Finnish islands ofÅland were analysed using five microsatellite loci. Spatial structure was delineated using both traditionalF-statistics and individually based approaches including spatial autocorrelation analysis. Our results indicate that the observed genotypic distribution is incompatible with that of a single, panmictic population. Isolation by distance appears important for shaping the genetic structure of pike in this region resulting in a largely continuous genetic change over the study area. Spatial autocorrelation analysis (Moran'sI) of individual pairwise genotypic data show significant positive genetic correlation among pike collected within geographical distances of less thanc. 100–150 km (genetic patch size). We suggest that the genetic patch size may be used as a preliminary basis for identifying management units for pike in the Baltic Sea. [ABSTRACT FROM AUTHOR]

The genetic population structure of yellow perch was assessed, with a focus on spawning groups within Lake Michigan. Six microsatellite DNA loci were evaluated, which had heterozygosities ranging from 0.21 to 0.86 in samples from seven Lake Michigan locations and six others in the north-central United States. Genetic variation within samples was somewhat higher in Lake Michigan than in surrounding inland lakes. Genetic variation was also higher in the north-central United States than in a sample from the eastern United States. Exact tests for population differentiation and the fixation index RST indicated little differentiation among spawning groups within southern Lake Michigan or Green Bay (pairwise RST values,−0.005 to +0.014; P > 0.05 after sequential Bonferroni correction for multiple tests). However, spawning groups in Green Bay were distinct from those in Lake Michigan, and all inland locations were distinct from one another as well as from those in Lake Michigan ( P < 0.01). All north-central U.S. samples were considerably different from the eastern U.S. sample (pairwise RST values 0.67-0.72). Although the sample sizes for northern Lake Michigan were limited, these fish grouped more closely with those from southern Lake Michigan than with those from Green Bay. There thus is evidence for the proposition that the yellow perch in Lake Michigan proper should be managed separately from those in Green Bay. [ABSTRACT FROM AUTHOR]

We supplemented physical-tagging data with genetic data to provide evidence for spawning-site and natal-site fidelity by two spawning populations of northern pike Esox lucius in Kabetogama Lake, Minnesota. A mark-recapture study supported previous reports that individual northern pike and other esocids tend to return to the spawning grounds that they used in previous years. Of 1,900 northern pike marked at two spawning sites in the first year of the study, 23% were recaptured on spawning grounds one to three times over the next 4 years. Of these recaptured fish, only 1.3% and 4.8%, respectively, of those marked at the two spawning sites were recaptured at the other site. Tag returns from anglers showed that the year-round ranges for fish from the two sites overlapped, so that lack of dispersal could not completely explain the high fidelity to spawning sites. Significant allele frequency differences at five microsatellite DNA loci between the 1983 ( P = 0.03) and 1985 ( P = 0.002) spawning populations indicated low levels of gene flow between the populations. This reproductive isolation would only be expected if most individuals first spawn at the site of their own birth and subsequently return to that site. We therefore conclude that northern pike in Kabetogama Lake exhibit both natal-site and spawning-site fidelity. Management on the basis of discrete spawning populations within lakes may thus be appropriate for a larger number of species and locations than commonly practiced. [ABSTRACT FROM AUTHOR]

ABSTRACT Artificial propagation and wild release may influence the genetic integrity of wild populations. This practice has been prevalent in fisheries for centuries and is often termed ‘stocking’. In the Laurentian Great Lakes (Great Lakes here‐on), walleye populations faced declines from the 1950s to the 1970s, prompting extensive stocking efforts for restoration. By the mid‐2010s, walleye populations showed signs of recovery, but the genetic legacy of stocking on population structure at the genomic level remains unclear. Using a dataset of 45,600 genome‐aligned SNP loci genotyped in 1075 walleye individuals, we investigated the genetic impacts of over 50 years of stocking across the Great Lakes. Population structure was associated with both natural geographic barriers and stocking from non‐native sources. Admixture between Lake Erie walleye and walleye from the re‐populated Tittabawassee River indicate that stocking may have re‐distributed putatively adaptive alleles around the Great Lakes. Genome scans identified FST outliers and evidence of selective sweeps, indicating local adaptation of spawning populations is likely. Notably, one genomic region showed strong differentiation between Muskegon River and walleye from the Tittabawassee River, which was re‐populated by Muskegon strain walleye, suggesting admixture and selection both impact the observed genetic diversity. Overall, our study underscores how artificial propagation and translocations can significantly alter the evolutionary trajectory of populations. The findings highlight the complex interplay between stocking practices and population genetic diversity, emphasising the need for careful management strategies to preserve the genetic integrity of wild populations amidst conservation efforts. [ABSTRACT FROM AUTHOR]

Presents articles related to molecular ecology. Development and characterization of microsatellite markers in Camellia japonica L.; Discussion of microsatellites in walleye Stizostedion vitreum; Isolation and characterization of microsatellites in albatrosses; Others.

Using single-locus microsatellite markers, we have resolved higher levels of genetic variation than previously reported for northern pike Esox lucius. We isolated 14 (AC) nṡ(TG) n microsatellite loci from a genomic library of northern pike. Primer pairs for the polymerase chain reaction (PCR) were developed for nine of these loci. With PCR, a DNA-amplifying technique, we were able to assess genetic variability using fish scales as our source of DNA. In four populations, we found four polymorphic loci with three or four alleles at each locus. Average heterozygosity at all loci was 0.075. Although this level of genetic variability is the highest reported for this species, it is much lower than that found for many other fish species by using microsatellite markers. Small numbers of founder fish, combined with loss of variation due to genetic drift in the small populations typical of northern pike, may explain the relatively low levels of genetic variation we found. [ABSTRACT FROM AUTHOR]

Presents a study of genetic microsatellites in the walleye, Stizostedion vitreum, a sport fish species mainly found in the North American waters. Characterization and development of the microsatellites; Description of the methods of the study; Results, conclusions and discussion.

Laboratory research has shown that female fish can pass toxic organochlorines (OCs) from their bodies to their eggs, killing their offspring if sufficient quantities are transferred. We conducted a controlled incubation study using gametes from a wild, OC-contaminated walleye (Sander vitreus) population (Bay of Quinte, Lake Ontario, Canada) in order to assess among-female variation in offspring early life survival in relation to ova concentrations of planar OCs (polychlorinated dibenzo-p-dioxins and furans and planar polychlorinated biphenyls) and a suite of other maternal and ova characteristics. Equal volumes of ova from each female were fertilized, pooled, and incubated together as an experimental cohort. Relative survival of each female's offspring was estimated as the proportion of surviving larvae (at approximately 5 d posthatch) that she contributed to the cohort as determined by microsatellite DNA parentage assignment. Total planar OC concentration (expressed as toxic equivalency of 2,3,7,8-tetrachlorodibenzo-p-dioxin) of ova was positively related to maternal age and size and to ova lipid content. However, early life survival did not decline with increasing ova planar OC concentrations. Similarly, we observed no significant relationships between early life survival and ova thiamine content, ova fatty acid composition, or maternal age or size. Early life survival was more strongly correlated with date of spawn collection, thyroid hormone status of the ova, and ovum size. Maternally transferred planar OCs do not appear to negatively influence female reproductive success in this walleye population. [ABSTRACT FROM AUTHOR]