Missouri River Dye Trace Experiment to Support Understanding of Free Embryo Drift

By Robb Jacobson, June 27, 2016

Missouri River scientists started the first phase of the pallid sturgeon free embryo drift study by employing a standard method to understand how hydraulic processes vary the rate of downstream transport of dissolved constituents and particles.  On June 26 they released 50 liters of rhodamine-WT dye (figure 1) into the Missouri River about 10 miles downstream of Fort Peck Dam, Montana (about 1.75 miles downstream of the Milk River confluence).  The downstream dispersion of dye is being recorded through a network of fluorometers distributed through about 84 miles of the river.  Rhodamine-WT is a harmless but very visible dye (figure 2) that is frequently used to study time of travel in river systems, usually to assess contaminant transport rates.

Figure 1.  USGS scientists prepare to mix rhodamine-WT dye for the dye trace experiment.  The suits are to keep the harmless dye off of clothing.

Figure 1. USGS scientists prepare to mix rhodamine-WT dye for the dye-trace experiment. The suits are to keep the harmless dye off of clothing.

Dye_Delivery

Figure 2. The rhodamine-WT dye is injected in the river uniformly across the channel.

The experiment is being helped a great deal by collaboration with US Army Corps of Engineers and Western Area Power Administration, who have arranged for near-steady flows for the duration of the experiment.

The initial effect of putting the dye in the river is dramatic, as nearly the entire river turned bright red (figure 3).  With continuous dilution, the bright red faded to burnt umber after drifting about 6 miles.  After 20 miles it was no longer visually identifiable, although the instruments have been able to detect the dye to concentrations as low as 1 parts per billion.

RedMissouri

Figure 3. Dramatic results were visual for the first 6 miles downstream.

Information from the dye trace is being used in near-real-time to refine the sampling strategy for the companion free embryo-drift experiment taking place in the afternoon of June 27.  More about the collaborative free embryo drift experiment in subsequent posts.

Posted in Methods, Upper Missouri and Yellowstone Rivers |

Pallid Sturgeon Free Embryo Drift Experiment Starts

By Robb Jacobson, and Casey Hickcox, June 26, 2016

Missouri River scientists started a large-scale collaborative study on June 24 to improve understanding of the fate of pallid sturgeon free embryos (from hatch through first feeding) in the Upper Missouri River (figure 1).  The study is being led by scientists from the U.S. Geological Survey with strong collaboration with Montana Fish Wildlife and Parks, U.S. Fish and Wildlife, U.S. Army Corps of Engineers, Bureau of Reclamation, and Western Area Power Administration. The ambitious study will use pallid sturgeon free embryos produced at Garrison National Fish Hatchery as tracers to test dispersal models and better understand transport dynamics.

Figure 1.  Map showing the Upper Missouri River study area.

Figure 1. Map showing the Upper Missouri River study area.

Results of previous studies indicate that pallid sturgeon free embryos need to drift long distances before they can safely settle out of the water column and begin feeding.  Better understanding of the dynamics in which the free embryos move downstream, and how long they need to safely settle out and begin to feed, may lead to important recovery options for this endangered fish. Crews will follow the free embryos downstream twenty-four hours a day for over a week, using ichthyoplankton nets to sample the drifting population.

The free embryo drift experiment is being complemented by assessment of river hydraulics.  Scientists from the USGS Columbia Environmental Research Center are collecting an extensive collection of velocity data using acoustic Doppler current profilers, in concert with a rhodamine dye trace.  The dye trace is intended to quantify the dispersion processes that spread free embryos out along the river through retention. In addition, collaborators with Montana Fish Wildlife and Parks are using tiny plastic beads as a tracer; the beads are designed to mimic free embryo settling behavior.  If the beads adequately mimic drifting free embryos, further studies could eliminate the need to use live sturgeon; saving time, money and resources. Other boat crews will be measuring the hydraulics of the Missouri River at a very high resolution to gain a better understanding of how these tiny fish move through the differing habitat conditions.

Posted in Early life history, Pallid sturgeon, Upper Missouri and Yellowstone Rivers | Tagged , , |

Sturgeon biology and plumbing

By Robert Jacobson, Aaron DeLonay, Kimberly Chojnacki, and Casey Hickcox

This spring, Columbia Environmental Research Center (CERC) scientists are conducting laboratory experiments to better understand how temperature affects early development of sturgeon species.  The emphasis is on quantifying development rates from fertilization of eggs to first-feeding larvae.    Previous experiments at CERC have explored relations between temperature and development but they had always been limited in the size and scope by laboratory facilities. To more fully explore early development of sturgeon species, CERC needed a new, updated, and larger version of our fish hatching system.

The new apparatus, designed by CERC biologist James Candrl and built by biologist (and master plumber) Dave Combs, offers scientists 24 temperature-controlled hatching and holding environments for the experiments, allowing for 6 different temperature treatments with 4 replicates.  The partially-recirculating systems can use either local well water or a reconstituted water made in large volumes at CERC to simulate any water quality where sturgeon may hatch and develop.  The system circulates the water through ultraviolet sterilizers to remove disease organisms and control fungus.  The sterilized water is routed through an electronically-controlled heating and chilling units that maintain the desired temperatures. The heated and chilled water is then pumped up and allowed to trickle down through large degassing columns that remove excess dissolved gasses that can accumulate and saturate the water when the temperature is manipulated, potentially harming young fish.    The degassed water is then routed to the hatching jars where the fertilized eggs are gently rolled by the moving water during incubation.  The hatching jars are constructed so hatched free embryos automatically overflow into holding tanks where they reside until they are ready to be transferred into rearing tanks and initiate feeding.

New hatching and rearing system at CERC, consisting of 24 McDonald-type hatching jars and free embryo holding tanks.

Figure 1. New hatching and rearing system at CERC, consisting of 24 McDonald-type hatching jars and free embryo holding tanks.

The new system provides great flexibility for evaluating development rates as a function of water temperature, and for comparing different sturgeon species and different genetic parentage within species.  Experiments planned for this spring include pallid sturgeon (Scaphirhynchus albus) and the closely related, the shovelnose sturgeon (Scaphirhynchus platorynchus).

From the backside of the hatching and rearing system showing overflow from McDonald-type hatching jars into free embryo holding tanks.  CERC sturgeon scientist-plumbers are in the background.

Figure 2. From the backside of the hatching and rearing system showing overflow from McDonald-type hatching jars into free embryo holding tanks. CERC sturgeon scientist-plumbers are in the background.

Posted in Early life history, Pallid sturgeon, Reproductive Female, Spawning, Sturgeon culture and propagation, Technology | Tagged , , |

Experiments on Early Sturgeon Development

By Robert Jacobson, Aaron DeLonay, Kimberly Chojnacki, and Casey Hickcox

Pallid sturgeon (Scaphirhynchus albus), like most fish, are cold-blooded.  This means that their metabolism is regulated by the temperature of the water in which they live.  As water warms, developmental rates of  sturgeon free embryos generally increase, up to a point where water becomes too warm and then they start to die.  If the water is too cold, then the free embryos cannot reach critical developmental milestones and they will also die.  In some parts of the Missouri River there is potential to influence water temperature — and possibly development and survival of early pallid sturgeon — by altering the way water is released from dams.  Management of dam releases to influence early sturgeon development presumes a rigorous, quantitative understanding of the relation between water temperature, sturgeon development, and the transition of sturgeon from one life stage (free embryos) to the next (benthically-oriented, feeding larvae).

Experiments at CERC this spring are intended to increase understanding the effect of temperature on free embryo development .  A new hatching system allows for precise temperature control and multiple treatments to evaluate hatch and free-embryo development.  In the first implementation this spring, four female pallid sturgeon were induced to spawn and their eggs were collected and manually fertilized using milt from three males.

Figure 1 CERC Biologist James Candrl checks to determine if a female pallid sturgeon is releasing eggs .

Figure 1 CERC Biologist, James Candrl, checks to determine if a female pallid sturgeon is releasing eggs .

Each family of eggs was separated into  replicate environments to have their development monitored at treatments with water temperatures ranging 14 – 26o C.  The data collected relate the rate at which free-embryo sturgeon reach critical developmental milestones with cumulative temperature experienced by the fish over time.  The experiments are designed to create a model to predict developmental transitions based upon cumulative temperature units and to explore how developmental trajectories vary through the entire range of river temperatures that pallid sturgeon spawn.

Newly hatched pallid sturgeon free embryo, approximately 7 mm in length.

Figure 2 Newly hatched pallid sturgeon free embryo, approximately 7 mm in length.

Posted in Early life history, Pallid sturgeon, Reproductive Female, Spawning | Tagged , , |

New Pallid Sturgeon Reports

By Robert Jacobson
Our blog has been quiet lately because we have been concentrating on writing and reporting. It has been said that if scientific information isn’t published, it’s as if it doesn’t exist. On rivers like the Missouri, where contentious management issues create a high demand for quality science, there is a special need to publish high-quality, peer-reviewed information in a timely manner. Our project scientists have been catching up during the last several months, striving to complete a backlog of progress reports on pallid sturgeon ecology. We have recently completed publication of 5 of these reports, including annual reports for 2012 and 2013, and 3 reports for the Effects Analysis; our 2014 annual report is being finalized and should be published in winter 2016. The 2012 annual report was a special effort to synthesize progress from studies 2005 through 2012.

Publications

The USGS’ investment in a high-quality peer review process delays publications somewhat, but results in scientific information products that can be considered credible, authoritative, and unbiased. The USGS production process assures that well-edited reports are published into the public domain and are freely available to stakeholders and the public.
These reports are available at the indicated pubs.usgs.gov websites:

DeLonay, A.J., Jacobson, R.B., Chojnacki, K.A., Braaten, P.J., Buhl, K.J., Eder, B.L., Elliott, C.M., Erwin, S.O., Fuller, D.B., Haddix, T.M., Ladd, H.L.A., Mestl, G.E., Papoulias, D.M., Rhoten, J.C., Wesolek, C.J., and Wildhaber, M.L., 2016, Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River: Annual report 2013: U.S. Geological Survey Open-File Report 2015–1197, 99 p. https://pubs.er.usgs.gov/publication/ofr20151197

DeLonay, A.J., Chojnacki, K.A., Jacobson, R.B., Albers, J.L., Braaten, P.J., Bulliner, E.A., Elliott, C.M., Erwin, S.O., Fuller, D.B., Haas, J.D., Ladd, H.L.A., Mestl, G.E., Papoulias, D.M., and Wildhaber, M.L., 2016, Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River: A synthesis of science, 2005-2012: U.S. Geological Survey, Scientific Investigations Report 2015-5145, 224 p. https://pubs.er.usgs.gov/publication/sir20155145

Jacobson, R.B., Parsley, M.J., Annis, M.L., Colvin, M.E., Welker, T.L., and James, D.A., 2015, Development of conceptual ecological models linking management of the Missouri River to pallid sturgeon population dynamics: U.S. Geological Survey, Open-File Report 2015-1038, 47 p. https://pubs.er.usgs.gov/publication/ofr20151038

Jacobson, R.B., Parsley, M.J., Annis, M.L., Colvin, M.E., Welker, T.L., and James, D.A., 2016, Development of working hypotheses linking management of the Missouri River to population dynamics of Scaphirhynchus albus (pallid sturgeon): U.S. Geological Survey, Open-file Report 2015-1236, 33 p. https://pubs.er.usgs.gov/publication/ofr20151236

Jacobson, R.B., Annis, M.L., Parsley, M.J., James, D.A., Colvin, M.E., and Welker, T.L., 2016, Scientific information to support the Missouri River pallid sturgeon effects analysis: U.S. Geological Survey, Open-file Report 2015-1226, 78 p. http://pubs.er.usgs.gov/publication/ofr20151226

Posted in Education, Pallid sturgeon | Tagged , , , |

Evidence of Successful Spawning by Endangered Pallid Sturgeon

By Aaron DeLonay, Kimberly Chojnacki and Robert Jacobson

Three free embryos that were collected by Comprehensive Sturgeon Research Project scientists in May 2014 were recently confirmed to be pallid sturgeon.  The three specimens were among several hundred paddlefish and closely-related shovelnose sturgeon collected from the Lower Missouri River immediately upstream of the confluence with the Platte River in Nebraska during 2014 (see previous entries, We’ve Only Just Begun and One Down, Several To Go).  All three pallid sturgeon free embryos were collected from the main channel of the Missouri River on May 30, 2014.  The specimens ranged in length from 9.59 to 10.42 mm, and were estimated to be between 1 to 3 days old based upon the developmental stage of the specimens and ambient river temperatures.

Pallid sturgeon free embryo at 2 days post hatch. At two days after hatching the free embryos are generally 9 to 11 millimeters (0.35 to 0.45 inch). (Photo by Kimberly Chojnacki, U.S. Geological Survey)

Pallid sturgeon hatch and disperse downstream from the spawning location as free embryos (figures 1 and 2).  Free embryos lack a well-developed mouth, eyes or fins, and rely a large yolk sac to fuel their rapid development as they drift downstream with the current (see previous entry, A Change Will Do You Good).  After 11-17 days these free embryos develop into larvae (figure 3) that settle to the bottom of the river and begin feeding.

Acipenseriformes free embryo (pallid sturgeon, shovelnose sturgeon, or paddlefish) collected from the Missouri River. (Photo by Dave Combs, U.S. Geological Survey)

Pallid sturgeon larvae at 14 days post hatch. On agerage, pallid sturgeon transition to active feeding at approximately 16 to 18 millimeters (about 0.7 inch). (Photo by Kimberly Chojnacki, U.S. Geological Survey)

The pallid sturgeon free embryos collected during 2014 were positively identified using genetic analyses developed by Jennifer Eichelberger and Dr. Edward Heist at Southern Illinois University Carbondale. Recent developments by Dr. Heist have resulted in genetic tests that use inexpensive Single Nucleotide Polymorphisms (SNP) assays to screen hundreds of specimens of sturgeon and paddlefish to identify possible pallid sturgeon embryos and larvae. Positive confirmation of the genetic identity of pallid sturgeon specimens is then determined using microsatellite DNA markers developed at SIU.   Microsatellite markers are also used to determine whether sturgeon free embryos collected in samples may be closely related, or possibly siblings from a single spawning event. Preliminary analyses suggest that the three specimens are not siblings from a single spawning female.

These new genetic identifications add to mounting evidence that critically endangered pallid sturgeon spawned successfully in the Lower Missouri River downstream of Gavins Point Dam, South Dakota during 2014. These findings build on previous year’s effort by the USGS, Nebraska Game and Parks Commission, and U.S. Army Corps of Engineers to track the reproductive migration and behavior of pallid sturgeon, and to locate and describe functional spawning habitat in the Lower Missouri River.  While successful spawning by the endangered fish was detected in the Lower Missouri River in 2014, it does not necessarily mean that the species is on its way to recovery.  During this study, USGS scientists and their collaborators have been able to track adults on their migrations to their spawning sites, describe their spawning behavior, and characterize the habitats they use in the Lower Missouri River.  Until 2014, scientists were unable to locate fertilized eggs or newly hatched embryos and larvae of pallid sturgeon, and therefore were unable to assess whether or where spawning by adults was successful.  These new findings indicate that suitable conditions and functional spawning habitats for pallid sturgeon do at times exist in the Lower Missouri River downstream of Gavins Point Dam, however pallid sturgeon populations remain small and successful reproduction and recruitment to the population is still quite limited.

 

Posted in Early life history, Pallid sturgeon | Tagged , , , , , |

Habitat surveys of 2015 pallid sturgeon spawning patches on the Yellowstone River

By Carrie Elliott, Robb Jacobson, and Casey Hickcox

USGS jetboat with a multibeam on the Yellowstone River

Figure 1. USGS research vessel outfitted with a compact multibeam sonar echosounder system with an inertial motion unit and real time kinematic positioning global positioning system (RTK GPS) surveys the Yellowstone River near Fairview, North Dakota.

During the last two weeks of June, USGS habitat crews surveyed the pallid sturgeon spawning reach of the Lower Yellowstone River near Fairview, North Dakota.  Using a compact multibeam sonar echosounder system with an inertial motion unit and real time kinematic positioning global positioning system (RTK GPS) mounted on a jet boat (figure 1), crews conducted high-resolution surveys and mapped features of the river bed in pallid sturgeon spawning patches (figure 2).  Multibeam sonar has been used in recent years to understand pallid sturgeon spawning habitats on the Lower Missouri but these efforts were the first to do so on the much shallower Yellowstone River.

Multibeam map showing features and sturgeon locations

Figure 2. Multibeam sonar depth map showing sand dunes and locations of reproductive female code 41 and multiple male pallid sturgeons from June 13 to June 15, 2015 during a presumed spawning event near Fairview, North Dakota.

Multibeam sonar maps the river bottom in great detail with a “sweep” or ping of soundings taken at up to 40 times per second. This generates a very dense cloud of points which allows scientists to generate high-resolution maps of the bottom of the river and visualize features such as sand dunes, submerged trees, and scour holes (figure 3). By conducting multiple passes with the sonar throughout the day,  sand dune movement can be mapped to calculate the rate of sand dune migration.  This information can be used to advance understanding of how spawning habitat may change while eggs are incubating in the substrate.

Multibeam representation of sturgeon spawning habitat

Figure 3. Image showing raw multibeam point cloud in the pallid sturgeon spawning habitat patch near river mile 5.9 on the Yellowstone River. The image is approximately 20 meters wide, is looking downstream on a sand bar, and shows sand dunes that are approximately half a meter high from crest to trough.

Posted in Habitat mapping, Methods, Pallid sturgeon, Reproductive Female, Spawning, Telemetry tracking, Upper Missouri and Yellowstone Rivers | Tagged , , |

Characterizing Spawning Habitat Substrate on the Lower Yellowstone River

By Eric Allen, Ed Bulliner, Carrie Elliott, Robert Jacobson

CERC Scientist Operates a Petite Ponar Sediment Sampler

Figure 1: A USGS scientist operates a Petite Ponar substrate sampler to sample bed material in an area identified as a pallid sturgeon spawning location on the Yellowstone River, North Dakota. (Photo by Pat Braaten, USGS)

Many sturgeon species spawn over coarse, hard substrate, and Missouri River scientists have thought that this was probably the case for the endangered pallid sturgeon (Scaphirhynchus albus)Characterizing the size, type, and distribution of spawning substrate is a key to understanding functional spawning habitat requirements for pallid sturgeon. The lack of channel modifications on the Yellowstone River, North Dakota and Montana, provides scientists with the opportunity to observe and characterize spawning habitat in a relatively unaltered system. In late June 2015, a team of biologists and physical scientists from CERC travelled to the Lower Yellowstone River to document and validate pallid sturgeon spawning locations and reproductive behaviors.  Locations of reproductive males and females were determined using radio telemetry, and spawning was documented using an acoustic camera and by recapturing females to confirm that they had dropped their eggs (see previous posts A Spawning Recorded in the Yellowstone River and It’s more than just gravel and sand!).

A Petite Ponar Sediment Sampler and sames are shown

Figure 2: Collecting and storing substrate samples using a Petite Ponar sampler (top right) for later analysis. (Photo by Pat Braaten, USGS)

Following an observed spawning event for female pallid sturgeon code 41 near river mile 5.9 (5.9 miles upstream of the confluence with the Missouri River), scientists used a Petite Ponar grab sampler (figures 1, 2) to retrieve bed substrate samples in and around the identified spawning habitat patches. The spawning area is predominately composed of sand dunes, although there was some spatial variation in substrate material. Samples from dune crests were sand, whereas samples from troughs downstream from dune crests often consisted of gravel, dominated by lignite believed to originate from local bedrock bluff outcrops (figure 3). Additional samples consisting of both sand and coarser material were obtained from an area approximately one river mile upstream from the spawning site in the vicinity of another spawning event.

A sample of sediment from the Yellowstone River is shown

Figure 3: A close-up image of lignite-dominated gravel sampled from a spawning area with Petite Ponar sampler. (Photo by Pat Braaten, USGS)

Georeferenced substrate samples will be used to characterize substrate particle sizes and to verify observations from hydrographic remote-sensing instruments, including sidescan sonars, a multibeam echosounder, and an acoustic camera.  Verifying substrate characteristics observed from remote-sensing instruments allows scientists to better interpret substrate size and distributions in imagery recorded by the instruments without the need for manual sampling. Such tools allow for rapid substrate classification over a larger area, and will further aid in identification of pallid sturgeon spawning habitats.

Posted in Habitat mapping, Spawning, Upper Missouri and Yellowstone Rivers | Tagged , , |

Through the Looking Glass

By Kimberly Chojnacki and Aaron DeLonay

Pallid sturgeon eggs are approximately three millimeters, or less than one eight of an inch, in diameter. While the eggs of this endangered sturgeon are small, the changes that happen inside are truly a wonder to behold. After fertilization (see previous entry, Spawning of Pallid Sturgeon for Crucial Experiments) scientists use microscopes to monitor the rapid development of sturgeon eggs. Researchers examine the developing embryos to determine the success of fertilization and to estimate the timing of hatch by monitoring developmental milestones. Development is controlled primarily by temperature. At 18 degrees Celsius, the single cell of the egg begins to divide within hours of fertilization (figure 1).

Figure 1.  Pallid sturgeon embryos approximately 8 hours after fertilization. (Photo by Kimberly Chojnacki, U.S. Geological Survey)

The neural plate or primitive streak develops a few days after fertilization (figure 2). The neural plate is the precursor to the central nervous system.

Figure 2.  The neural plate or primitive streak of developing pallid sturgeon embryos can be seen 2 days after fertilization. (Photo by Kimberly Chojnacki, U.S. Geological Survey)

A well-developed embryo can be seen inside the chorion (outermost membrane of the egg) approximately 4 days after fertilization.  At this stage, the tail of the embryo is wrapped around its body, covering part of the head (figure 3).

Figure 3. Well-developed pallid sturgeon embryos can be seen approximately four days after fertilization. (Photo by Kimberly Chojnacki, U.S. Geological Survey)

These well-developed embryos can even be seen wriggling inside the chorion (see video below).  After approximately 4 to 5 days at 18 degrees Celsius the chorion starts to weaken and the embryos begin to hatch.

Posted in Early life history, Pallid sturgeon | Tagged , , |

Spawning of Pallid Sturgeon for Crucial Experiments

By Kimberly Chojnacki, Aaron DeLonay, and Robert Jacobson

Researchers at the USGS Columbia Environmental Research Center (CERC) have been making preparations to spawn pallid sturgeon to provide eggs and larvae for experiments.  During March and April, the captive population of adult, hatchery-origin pallid sturgeon maintained at CERC were weighed and examined for reproductive readiness (figure 1).  Non-invasive ultrasound technology was used to determine if the pallid sturgeon would be ready to produce viable eggs and sperm in the coming weeks (see previous entry, Did she or didn’t she?).  Fish determined to be approaching reproductive condition were moved to indoor holding tanks so that water temperature could be tightly controlled and their condition could be closely monitored.  The reproductive readiness of female sturgeon was tracked using biopsies and microscopic examination of extracted eggs as the potential spawning day drew near.

Biologists at Columbia Environmental Research Center drawdown and seine a pond to collect reproductive pallid sturgeon. The pond has been specially designed to provide turbid, flowing water that pallid sturgeon need to thrive.  Photo by Aaron DeLonay.

As the female readiness to spawn became imminent, four male sturgeon were given a hormone injection to induce the production of sperm.  Within 48 hours biologists were able to collect milt containing viable sperm from the males.  The milt was refrigerated and stored with an extender until the females were ready.  Finally, at 3:00 am on Tuesday, May 5th, researchers administered the first of two hormone injections to four female pallid sturgeon.  The second, resolving dose was administered 12 hours later.  Ovulation occurred 14-18 hours after the resolving dose on the morning of Wednesday, May 6th.  Biologists began the process of extracting the ovulated eggs from the females at 7:00 am.

Eggs were fertilized in the laboratory with milt (sperm) from 4 males.  Extracted eggs were used in experiments to measure egg density and adhesiveness (figure 2).  Fertilized eggs were incubated in flowing water for approximately 4 days.  Hatched free embryos were used in outdoor stream experiments to evaluate initial dispersal behaviors (see previous entry, Studies of Lake Sturgeon Free Embryo Dispersal Begin).

 

Pallid sturgeon eggs become adhesive minutes after fertilization. Scientists are working to understand the factors that influence the adhesiveness of sturgeon eggs. (Photo by Aaron DeLonay, U.S. Geological Survey)

Improved understanding of the reproductive ecology of pallid sturgeon requires integration of controlled experiments with knowledge gained from studies of fish in the river.  The ability to carry out experiments on pallid sturgeon depends on having a captive population of adult fish available, the knowledge on how to spawn them and raise their young, and the facilities to study these fish in conditions that approximate the river conditions.

Posted in Early life history, Pallid sturgeon, Sturgeon culture and propagation | Tagged , |