Gamete and larval collection methods and hatchery rearing environments affect levels of genetic diversity in early life stages of lake sturgeon (Acipenser fulvescens) (original) (raw)
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Transactions of the American Fisheries Society, 2020
Lake Sturgeon Acipenser fulvescens populations throughout the Great Lakes have experienced declines. As a result, Lake Sturgeon have been stocked at several locations, including the Oswegatchie River in New York State, where Lake Sturgeon are listed as Threatened. The goal of New York's Lake Sturgeon stocking program has been the establishment of self-sustaining populations in six out of the seven management units in order to meet delisting criteria. Due to Lake Sturgeon's long lifespan and late sexual maturity, there is a significant delay before it can be determined whether natural reproduction is occurring at the reintroduction site. Our objective was to determine whether the recently captured Lake Sturgeon from the Oswegatchie River were of hatchery origin and whether natural reproduction was occurring in the river. Age data and genetic data from 12 microsatellite loci were collected from 38 individuals from the Oswegatchie River. The genetic data were used to reconstruct families using the software COLONY and STRUCTURE. Genetic diversity of the Oswegatchie River population was also compared to other natural and introduced Lake Sturgeon populations in the region. The combination of family reconstruction and age data indicated that natural reproduction is occurring in the Oswegatchie River. Individuals presumed to be recruited had ages ranging from 6-12 years. It is often thought female Lake Sturgeon typically do not reach sexual maturity until about 20 years. Only 12-15 years had elapsed since the earliest times of stocking, suggesting the possibility that remnant native females remained in the system or stocked female lake sturgeon have reached early sexual maturity. The genetic diversity of the Oswegatchie River Lake Sturgeon population is comparable to other nearby natural populations. However, the effective population size (N e) was lower than many of the natural populations. As natural reproduction continues in the Oswegatchie River, N e will likely increase.
2010
Natal philopatry in lake sturgeon (Acipenser fulvescens) has been hypothesized to be an important factor that has lead to genetically distinct Great Lakes populations. Due to declining abundance, population extirpation, and restricted distribution, hatchery supplementation is being used to augment natural recruitment and to reestablish populations. If hatchery-reared lake sturgeon are more likely to stray than naturally produced individuals, as documented in other well-studied species, outbreeding could potentially jeopardize beneficial site-specific phenotypic and genotypic adaptations. From 1983 to 1994, lake sturgeon propagated using eggs taken from Lake Winnebago adults (Lake Michigan basin) were released in the St. Louis River estuary in western Lake Superior. Our objective was to determine whether these introduced individuals have strayed into annual spawning runs in the Sturgeon River, Michigan. Additionally, we estimated a natural migration rate between the Sturgeon River and Bad River, Wisconsin populations. Presumed primiparous lake sturgeon sampled during Sturgeon River spawning runs from 2003 to 2008 were genotyped at 12 microsatellite loci. Genotypic baselines established for the Sturgeon River (n = 101), Bad River (n = 40), and Lake Winnebago river system (n = 73) revealed a relatively high level of genetic divergence among populations (mean F ST = 0.103; mean R ST = 0.124). Likelihood-based assignment tests indicated no straying of stocked Lake Winnebago strain lake sturgeon from the St. Louis River into the Sturgeon River spawning population. One presumed primiparous Sturgeon River individual likely originated from the Bad River population. Four firstgeneration migrants were detected in the Sturgeon River baseline, indicating an estimated 3.5% natural migration rate for the system.
Journal of Applied Ichthyology, 2017
The primary objective of this study was to use direct (acoustic telemetry) and indirect (genetic assignment) methods to characterize basic aspects of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) breeding ecology. Specifically, data on natal origin, spawning habitat, spawn sex-size structure, and sex-specific residence times, spawning site fidelity, seasonal movements and degree of straying between demographically and genetically independent populations. A secondary benefit of the project was the nonspawning period movements of tagged fish. The analysis was based on acoustic telemetry and genetic assignment tests for individuals captured from the Menominee, Peshtigo, Oconto and Fox rivers (draining into Green Bay) in Wisconsin, which represent the only spawning rivers in western Lake Michigan. Sturgeon (N = 160) were captured during the spring (18 April-25 May) of 2011-2015 using large dip nets (51%) and electro fishing (49%). Captured sturgeon were genotyped and assigned to a Great Lakes river population using likelihood-based estimators based on microsatellite (N = 13) genotype and mtDNA haplotype frequencies. Assignments revealed that captured adults from four Green Bay rivers were of an aggregate composition from the overall sample size (N = 160) of 38.2% assigned to the Fox-Wolf River population, 23.5% to the Menominee River population and 37.4% to the Peshtigo-Oconto River population. One adult female sturgeon was assigned to the Manistee River population (eastern Lake Michigan). Of the 160 captured adults, 115 spawning lake sturgeon were tagged with surgically inserted acoustic tags/transmitters (Vemco V-16). Collected lake sturgeon ranged in size from 114 cm to 185 cm total length, and girth from 43 cm to 74 cm. Visual examination during surgery confirmed the sex of each individually tagged fish. Timing of post-surgery departure from the rivers differed significantly between males (mean 35.6 days) and females (mean 8.9 days), but was not significant because of the large variability. Postsurgery residence time was longer for the Menominee River sturgeon compared to individuals from the other rivers. More than twice as many males versus females were detected in the four rivers during the non-spawning period. A subsample of 53 lake sturgeon returned to one of the four rivers 1.9-3.4 years after surgery. Eight males returned to one of the four rivers in successive springs but no female sturgeon returned in
Journal of Great Lakes Research, 2003
The lake sturgeon (Acipenser fulvescens) has recently become a high priority for restoration management because of the near extinction of the species from many areas of North America. The identification of the level of population differentiation that naturally exists among lake sturgeon populations will be useful in the development of management plans to conserve and restore diversity, and in the choice of donor populations to use for re-introduction. Genetic variation among and within 210 lake sturgeon collected from seven locations (St. Lawrence River, Des Prairies River (tributary to the St. Lawrence River), Mattagami River (Hudson Bay drainage), Menominee River (Lake Michigan drainage), Wolf River (Lake Michigan drainage), Niagara River, and Lake Erie) was examined based on allelic variation at seven microsatellite loci (four disomic and three putative tetrasomic). High levels of variability were detected at these loci. Analyses revealed an average of 8.6 alleles per locus (range 5 to 12 alleles per locus) and heterozygosity values at the four disomic loci ranging from 0.46 to 0.66. Multivariate factor analysis of Nei's genetic distance values produced three distinct population groups that were organized by geography: 1) Mattagami (northern Quebec), 2) Menominee/ Wolf (Lake Michigan-Wisconsin), and 3) St. Lawrence/ Des Prairies/ Niagara/ Erie (lower Great Lakes). Differences based on G-tests summed over all loci occurred between all possible paired comparisons of the collections (P < 0.01). These analyses indicated that lake sturgeon populations are differentiated within the Great Lakes basin. Managers of this species will need to identify individual populations in their jurisdictions and provide separate consideration for their conservation and rehabilitation.
Journal of Applied Ichthyology, 2011
Lake sturgeon (Acipenser fulvescens) are a species of conservation concern across their range, with impoundments and exploitation acting as significant impediments to their recovery. Northern Ontario contains some of the few remaining intact systems with healthy lake sturgeon populations because of low exploitation and undammed, unregulated watersheds. Although preliminary research suggests that northern Ontario lake sturgeon are genetically distinct from depleted sturgeon populations in the Great Lakes basin, this region represents a large gap in our understanding of genetic diversity of lake sturgeon. Recent identification of hydroelectric development potential in four major rivers in northern Ontario may pose future threats to these populations. The two goals of this study were to address the lack of genetic information from a significant portion of the species range, and to compare levels of local and regional diversity between relatively intact systems and more intensively studied (and fragmented) areas to the south. Comparison of 23 putative populations from three major drainages identified three divergent genetic groups which corresponded with historical drainages more than contemporary watersheds. The three groups reflected colonization from Mississippian and Missourian glacial refugia, as well as a novel third group in western Ontario characterized by low genetic variability. Diversity within populations similarly reflected historical influences more than anthropogenic stressors, including impoundments and population abundances resulting from harvest. Genetic similarities among geographically separated populations within major drainages underscore their historical connections, reflecting lake sturgeon dispersal abilities and the importance of habitat connectivity.
Environmental Biology of Fishes, 2011
Lake sturgeon (Acipenser fulvescens) are of conservation concern throughout their range. Many populations are dependent on fluvial habitats which have been increasingly impacted and fragmented by dams and human development. Although lake sturgeon were once abundant in the Ottawa River and its tributaries, historical commercial harvests and other anthropogenic factors caused severe declines and low contemporary numbers in lake sturgeon populations. Contemporary habitat fragmentation by dams may be increasing isolation among habitat patches and local rates of decline, raising concerns for persistence of local populations. We used microsatellite DNA markers to assess population structure and diversity of lake sturgeon in the Ottawa River, and analyzed samples from 10 sites that represent more than 500 km of riverine habitat. To test for evidence of anthropogenic fragmentation, patterns of genetic diversity and connectivity within and among river segments were tested for concordance with geographic location, separation by distance and obstacles to migration, considering both natural and artificial barriers as well as barrier age. Despite extensive habitat fragmentation throughout the Ottawa River, statistical analyses failed to refute panmixia of lake sturgeon in this system. Although the long generation time of lake sturgeon appears to have effectively guarded against the negative genetic impacts of habitat fragmentation and loss so far, evidence from demographic studies indicates that restoring connectivity among habitats is needed for the long-term conservation and management of this species throughout this river system.