Comprehensive Sturgeon Research Project Blog - 2021

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The USGS Comprehensive Sturgeon Research Project is a multi-year, interdisciplinary research study to determine factors leading to spawning and survival of the endangered pallid sturgeon and the closely related shovelnose sturgeon. 

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Mobile Ultrasound Technology Empowers Field Biologists

By Sabrina Davenport, Patrick Braaten, and Casey Hickcox

March 8, 2021

 

Knowing the sex and reproductive status of pallid sturgeon is important for many monitoring and research activities, and ultrasound is a valuable tool to address these uncertainties. To enhance monitoring and research capabilities, the Comprehensive Sturgeon Research Project will be transferring new, low-cost mobile ultrasound technology from the laboratory to field biologists in 2021.  Previously, ultrasound assessments had been administered by specially trained staff on a limited basis.  These trained sonographers met field biologists on the river after they captured pallid sturgeon.  Ultrasound assessments determined if fish were male or female, and helped identify fish that were candidates for surgical implantation of telemetry transmitter or valuable for transport to the hatchery as parental broodstock. When field biologists captured pallid sturgeon and a trained sonographer wasn’t available, the sturgeon would often be released without knowledge of sex or reproductive status.  Oftentimes, rare pallid sturgeon that were not evaluated were transported from the river to a hatchery unnecessarily only to be returned when it was determined it was not reproductively mature.  Even when a sonographer was available, pallid sturgeon had to wait several hours for evaluation while biologists worked to carefully maintain the sturgeon in tanks on the boat to minimize stress.

Ultrasound imagery of stage-2 adult, female pallid sturgeon with an arrow pointing to the ovigerous folds and the ovary outlined

Ultrasound imagery of stage-2 adult, female pallid sturgeon with an arrow pointing to the ovigerous folds and the ovary outlined (no oocytes are visible). Side view (left) and abdominal view (right).

(Public domain.)

In 2021, field biologist throughout the Missouri and Yellowstone River basins will be trained on new, lower-cost and more-portable ultrasound platforms (continuing efforts from previous blog posts, The Cold Never Bothered Us Anyway and Training Sturgeon Surgeons). The new systems use portable ultrasound probes that connect to cell phones and tablets . Advances in technology and portability have reduced the costs of ultrasounds suitable for field use from nearly $35,000 to as little as $6,000. The new devices can be widely distributed and carried as standard equipment on watercraft sampling in remote areas for immediate assessment of sturgeon sex and reproductive readiness. Ultrasound imagery can be saved to the device’s memory for future reference or sent over a cellular internet connection to trained specialists in the laboratory for real-time expert consultation. Testing of the new ultrasound technologies was performed with hatchery brood stock in early 2021, and ultrasound imagery from the low-cost units was quite good in comparison to the higher-cost units (see figures).

Ultrasound imagery of stage-4/5 adult female pallid sturgeon that will be ready to spawn during the coming spring

Ultrasound imagery of stage-4/5 adult female pallid sturgeon that will be ready to spawn during the coming spring (arrows indicate presence of oocytes [eggs]).  Side view (left) and abdominal view (right).

(Public domain.)

Immediate knowledge of sex and reproductive readiness allows field biologists to make informed rapid decisions on how best to handle and treat the rare sturgeon and minimize stress while collecting as much information as possible. For example, if a fish is determined to be a female in reproductive condition based on ultrasound imagery, that fish will be a focus of intensive tracking to assess spawning migrations and identify spawning locations.  This will allow biologists to better interpret observations of critical reproductive behaviors and focus additional resources on mapping and characterizing important spawning habitats.

 

 

New Foundation for Genetic Identification of Scaphirhynchus Sturgeon

By Kimberly Chojnacki, Richard Flamio, Jr., Dr. Edward Heist, and Aaron DeLonay

March 1, 2021

 

Researchers from the U.S. Geological Survey, Columbia Environmental Research Center and U.S. Geological Survey, Wetland and Aquatic Research Center recently published the results of a study conducted in collaboration with scientists at Southern Illinois University Carbondale.  The scientific journal article, “Production of haploid gynogens to inform genomic resource development in the paleotetraploid pallid sturgeon (Scaphirhynchus albus)”, authored by Richard Flamio Jr. and others was published in the journal Aquaculture.  The principal study investigators are from Dr. Edward Heist's laboratory at the Center for Fisheries Aquaculture and Aquatic Sciences at Southern Illinois University Carbondale.  Hybridization with the closely related and more common shovelnose sturgeon is one of several threats to the endangered pallid sturgeon. Current molecular markers cannot reliably distinguish among the two pure Scaphirhynchus species and multigenerational backcrosses (hybrids). Identification of pure pallid sturgeon for use as broodstock in conservation propagation and augmentation efforts is critical to avoid jeopardizing species integrity while preserving genetic diversity and conserving local adaptation. Genotypes from a larger panel of unlinked single-nucleotide polymorphisms (SNPs) can provide greater resolution between the two species and hybrids.  Development of the SNPs is complicated, however, by the evolutionary history of the sturgeon that has resulted in a whole genome duplication event (a doubling of the number of paired chromosomes of these two sturgeon species compared to other species).  In this multi-year study, methods were developed to successfully produce pallid sturgeon offspring with DNA contributed only by the female parent; these offspring are called haploids.  The simplified genome of the haploids can be more easily studied.  Scientists used a technique called flow-cytometry to confirm that the haploid specimens produced in the study had only half the number of chromosomes of normal pallid sturgeon.  Genetic analyses using 19 sturgeon microsatellite loci and four paddlefish loci confirmed that haploid specimens were 100% homozygous. The results of this study are a critical step necessary to inform future development of thousands of new, cost-effective genetic markers for Scaphirhynchus sturgeon. 

Phenotypes of sturgeon specimens (11–12 days post hatch)

Phenotypes of sturgeon specimens (11–12 days post hatch) representative of (a) normal, biparental sturgeon, and (b) haploid sturgeon (having only maternal genetic contribution). (Public domain.)

This study is part of the Comprehensive Sturgeon Research Project (CSRP) funded by the U.S. Army Corps of Engineers, Missouri River Recovery–Integrated Science Program and the U.S. Geological Survey, Ecosystems Mission Area.  Collaboration with Southern Illinois University Carbondale, Center for Fisheries, Aquaculture, and Aquatic Sciences was funded by CSRP through the Cooperative Ecosystem Studies Unit network grant program within the U.S. Geological Survey.

Citation: Flamio, R., Chojnacki, K.A., DeLonay, A.J., Dodson, M.J., Gocker, R.M., Jenkins, J.A., Powell, J., and Heist, E.J., 2021. Production of haploid gynogens in order to inform genomic resource development in the paleotetraploid pallid sturgeon (Scaphirhynchus albus). Journal of Aquaculture. https://doi.org/10.1016/j.aquaculture.2021.736529

 

 

 

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