Remote Technology Monitors Sturgeon Spawning

By Aaron DeLonay, Kimberly Chojnacki and Chad Vishy

Scientists from the U.S. Geological Survey and their partners have been successful in using telemetry to track adult sturgeon to their spawning locations on the Missouri and Yellowstone Rivers for several years (see previous blog entry A Spawning Recorded in the Yellowstone River). Despite locating spawning locations at a relatively fine resolution (10’s to 100’s of m), we continue to struggle to observe spawning and egg deposition in the swift turbid water. The definition of spawning habitat suitability and functionality is dependent upon adequately identifying quality spawning habitat (see previous blog entry Spawning patches on the Yellowstone River.) Scientists at the Columbia Environmental Research Center (CERC) are conducting studies to adapt new methods and technology to study spawning behavior and more precisely locate and characterize areas selected by pallid sturgeon for egg deposition. These studies will hopefully allow scientists to assess what characteristics of functional spawning habitats attract adults and result in the survival of developing embryos. This would help to both understand why sturgeon are having difficulty reproducing successfully and provide guidance for enhancing or creating functional spawning habitats.

One way in which scientists at CERC do this is to work with the closely related shovelnose sturgeon. We have implanted test shovelnose sturgeon with miniature acoustic transmitters and release them into specially constructed experimental mesocosms at CERC (see previous blog entry We Just Wanna See What Happens Down There!). Circulators in the mesocosm provide a continuous current that simulates conditions in the Missouri River. Scientists can manipulate the substrate in the mesocosms to provide patches of either gravel or cobble where sturgeon may spawn. We map fish locations using an array of 8 to 16, precisely arranged hydrophones connected by cables to a telemetry receiver. The hydrophones detect the acoustic pulses of the transmitters in the sturgeon. The telemetry receiver records each transmitted pulse and uses the signal detected by the array of hydrophones to calculate the precise position of each sturgeon in the pond, as often as once per second. In some trials an ARIS multibeam acoustic camera has been placed in the center of the pond to allow researchers to record sturgeon behavior.

Figure 1.  Acoustic telemetry transmitter used to monitor shovelnose sturgeon during spawning in specially constructed ponds at the Columbia Environmental Research Center.

Figure 1. Acoustic telemetry transmitter used to monitor shovelnose sturgeon during spawning in specially constructed ponds at the Columbia Environmental Research Center.

Figure2_3D-Telemetry Implant SNS_Small

Figure 2. A USGS Scientist surgically implants an acoustic telemetry transmitter in a shovelnose sturgeon to monitor spawning behavior during controlled experiments.

The spawning trials begin when female and male sturgeon are primed with hormone injections and released into the pond to let nature take its course. Scientists can then evaluate the performance of the miniature transmitters by watching the tracks of individually tagged fish as the males and females move, come together, and finally spawn by releasing eggs and milt. Comparing the ARIS sonar imagery with the precise tracks from the telemetry system allows scientists to identify movement patterns that indicate spawning and egg deposition. If the transmitters perform well in the mesocosm and spawning behavior can be identified through patterns of movement, then the transmitters could be used in the wild fish in the river to determine the precise timing and location of spawning, and the habitat characteristics where egg deposition occurs. Scientists can then better study if these spawning patches are functional, and whether the quality of the patches used by sturgeon is limiting embryo development and survival.

Figure3_3D Telemetry Shovelnose Spawning_2255-2256_kc

Figure 3. Locations of one female and two male shovelnose sturgeon showing movement during a brief reproductive encounter in a specially constructed, experimental mesocosm used to study sturgeon spawning behavior. Sturgeon are tagged with transmitters and their locations are recorded using a three-dimensional acoustic telemetry array.

 

Video 1. Video of ARIS Sonar imagery showing a female and two male shovelnose sturgeon over an egg deposition location recorded during controlled experiments to study spawning behavior.

 

 

 

 

 

Posted in Spawning, Technology, Telemetry tracking | Tagged , , |

River of sand

By Carrie Elliott

Pallid sturgeon are benthic fish, which means they live near the bottom of the river.  We know from hydroacoustic mapping that the bottom of the Missouri River is mostly made of sand, and that in much of the channel the sand dunes are moving rather quickly; at times up to 3 meters per hour!  Pallid sturgeon navigate through and use sand dunes and the flow fields around dunes when they migrate upstream to spawn.  It is also highly likely that that sand dunes affect feeding patterns through macroinvertebrate drift and that river substrate type and disturbance regime is related to macroinvertebrate food production in the river. We’ve been using a multibeam echosounder and precise GPS positioning to survey the river, monitor change, and measure rates of sand dune movement.  These measurements help us to understand how environments on the bottom of the river that pallid sturgeon use change with flow, and if the places on the river where sturgeon spawn (revetment and rocky bedrock outcrops like you can see in Figure 1) are stable or instead subject to episodic erosion and deposition.

Animation showing three multibeam echosounder surveys of the Missouri River on July 15, 2015.  Discharge was 112,000 cubic feet per second and surveys were about 1 hour apart.

Figure 1: Animation showing three multibeam echosounder surveys of the Missouri River on July 15, 2015. Discharge was 112,000 cubic feet per second and surveys were about 1 hour apart.

Posted in Habitat mapping | Tagged , , |

Transitioning from One Life Stage to the Next

2016 Pallid Sturgeon Free Embryo Drift Study Continues and is Far from Completion

By Pat Braaten

July 20, 2016

The release of nearly 700,000 pallid sturgeon free embryos on June 27 (see previous blog entry 700,000 Baby Fish) marked the start of the most spatially extensive drift and dispersal study ever conducted in the Missouri River basin.  Following release of the newly hatched pallid sturgeon, crews started to sample for the drifting free embryos on June 27, first at a site only a few miles downstream.  The sampling regime moved progressively downstream as the free embryos drifted, and sampling continued round-the-clock (see previous blog entry Night Sampling for Pallid Sturgeon Free Embryos).  Two sites (one near Culbertson, MT at river mile 1620 and the other at Williston, ND at river mile 1550) were sampled for multiple continuous 24-hr cycles in an attempt to characterize the entire distribution of drifting free embryos arriving, passing, and trailing slowly through these sampling sites. On July 8, nearly 12 days after the free embryos were released 210 miles upstream, sampling for free embryos that might still be drifting came to an end as the U. S. Fish and Wildlife Service team of Ryan Wilson and Sam Hultberg cranked the net winches for the last time, flushed the paired larval nets in the flowing river near Williston, and searched the detritus for any potential pallid sturgeon free embryos remaining in the drift.

Does that last pull of larval nets on July 8 mark completion of the free embryo study? Not at all!  Rather, it completes one aspect of the study – sampling for free embryos as they disperse downstream with the current.  Next, a second and equally important aspect of the study starts.  Growth and development of surviving free embryos (see previous blog entry A Change is Gonna Come) eventually leads to settlement, the developmental process by which free embryos transition from drifting to associating with (settling on) river bed habitats as larvae.  Following exhaustion of their yolk-supply feeding reserves, the settled larvae start to feed on invertebrates in the river.  With termination of drift sampling, other crews initiated the second important aspect of the study focused on capturing larval pallid sturgeon that may have survived and settled on the river bed.

Crews on July 7 and July 8 sampled multiple sites with a benthic beam trawl, spanning a 24-mile reach extending from river mile 1560 (upstream from Williston) down to about river mile 1536 (downstream from Williston in the flowing headwaters of Lake Sakakawea).  The trawling of multiple habitats yielded much of what was expected – young channel catfish, sicklefin chubs, and a smattering of other species.  But, beam trawling also produced five small sturgeon, ranging in length from 31-41 mm.  Two of the small sturgeon were sampled at river mile 1536.  Because pallid sturgeon and shovelnose sturgeon at this small size are visually nearly identical, genetic testing is required to differentiate the two species. Further genetic testing is then required to demonstrate that a captured pallid sturgeon larvae is one of the 700,000 released upstream.

Figure 1.  A 31-mm sturgeon captured in the Missouri River near Williston, North Dakota, on July 8 using a beam trawl. (Photograph by Pat Braaten, U.S. Geological Survey)

Figure 1. A 31-mm sturgeon captured in the Missouri River near Williston, North Dakota, on July 8 using a beam trawl. (Photograph by Pat Braaten, U.S. Geological Survey)

Beam trawling through a large reach of the Missouri River and the headwaters of Lake Sakakawea will continue for several weeks in an attempt to capture young pallid sturgeon originally released as free embryos, and to determine where settlement and survival may have happened. All small (e.g., < 130 mm) sturgeon collected will be subjected to genetic testing.  Along with the field work, laboratory work continues as personnel process drift samples, and sort and count pallid sturgeon free embryos and beads collected during the drift-sampling framework.

Figure 2.  Student Contractor Garrett Cook processes a drift sample collected on June 27 shortly after the free embryos and beads were released.  Note the small cluster of pallid sturgeon free embryos and green beads in the lower portion of the sorting tray.  (Photograph by Pat Braaten, U.S. Geological Survey).

Figure 2. Student Contractor Garrett Cook processes a drift sample collected on June 27 shortly after the free embryos and beads were released. Note the small cluster of pallid sturgeon free embryos and green beads in the lower portion of the sorting tray. (Photograph by Pat Braaten, U.S. Geological Survey).

It cannot be overstated – dedication to this project has been outstanding.  All individuals – ranging from hatchery personnel for their superb fish culture practices to the fish samplers for their long day and night shifts – should be commended for their great work in support of this highly relevant scientific information.

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

A Change is Gonna Come

By Kimberly Chojnacki, and Aaron DeLonay

With all the discussion of free embryos this summer, some readers may be left wondering what, exactly, is a ‘free embryo’.  A free embryo is a developing fish no longer within a protective chorion (egg envelope), from the time of hatch to the initiation of active feeding.  This life stage is marked by rapid development, growth, and change.  Newly hatched pallid sturgeon free embryos are generally 7-9 millimeters long with a large yolk-sac to fuel the rapid development and growth of the tiny fish.  The free embryos hatch without a well-developed mouth, eyes, gills, fins, or the fleshy, whiskerlike barbels near the mouth of sturgeon (figure 1).  Without fins, a newly hatched pallid sturgeon free embryo has limited ability to control its movement in the river current for several days after hatch.  Water temperature is considered to be the most important environmental factor influencing the development of this early life stage.

Figure 1.  Pallid sturgeon free embryos on the day of hatch, approximately 8-9 mm (about 0.33 of an inch) in length.   .  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

Figure 1. Pallid sturgeon free embryos on the day of hatch, approximately 8-9 mm (about 0.33 of an inch) in length.  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

 

At approximately 20 °C and 2 days after hatch, eyes of the free embryos have become pigmented, and pectoral fins buds, and barbel buds are visible (figure 2).

Figure 2. Pallid sturgeon free embryo at approximately 2 days post-hatch, approximately 11-12 mm (about 0.45 of an inch) in length.  .  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

Figure 2. Pallid sturgeon free embryo at approximately 2 days after hatch, approximately 11-12 mm (about 0.45 of an inch) in length.  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

By approximately the fifth day after hatch, the free embryos are developing gill filaments, a dorsal fin, and the barbels continue to grow (figure 3).

Figure 3.  Pallid sturgeon free embryo at approximately 5 days post-hatch, approximately 14-15 mm (about 0.57 of an inch) in length.  .  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

Figure 3. Pallid sturgeon free embryo at approximately 5 days after hatch, approximately 14-15 mm (about 0.57 of an inch) in length.  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

At approximately 20 °C and 10 days after hatch, the pallid sturgeon free embryos look much more like miniature versions of their parents with a broad, flat rostrum (snout or nose), fleshy barbels bordering the protrusible mouth, and large pectoral fins (figure 4).  The free embryos are now approximately 17-19 millimeters long and are ready to begin active feeding and transition to the larval stage.

Figure 4.  Pallid sturgeon free embryo at approximately 10 days post-hatch, approximately 19-20 mm (about 0.77 of an inch) in length.  (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

Figure 4. Pallid sturgeon free embryo at approximately 10 days after hatch, approximately 19-20 mm (about 0.77 of an inch) in length. (Photograph by Kimberly Chojnacki, U.S. Geological Survey)

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

Lake Sakakawea Delta and Headwaters

By Robert Jacobson

High, eroding riverbanks are common in the Upper Missouri River between Fort Peck Dam and Williston, North Dakota

Figure 1. High, eroding riverbanks are common in the Upper Missouri River between Fort Peck Dam and Williston, North Dakota

On July 5, the USGS acoustic Doppler current profiler crews worked from just south of Williston, North Dakota, downstream to the headwaters of Lake Sakakawea. The objective of this part of the study was to characterize velocities and habitat complexity in the part of the system that is thought to be fatal to pallid sturgeon free embryos. A seminal paper by Dr. Chris Guy and colleagues established in 2015 that low dissolved oxygen in the headwaters of Fort Peck Lake was the most likely cause of mortality for pallid sturgeon free embryos in that part of the Upper Missouri River system (Guy and others, 2015). This conclusion has been broadly accepted to hold true for Lake Sakakawea as well. Research into the potential anoxic zone in Lake Sakakawea is continuing through Montana State University; our data are intended to provide some additional physical context to help understand the role of anoxia in pallid sturgeon ecology.

In the transition to the delta, riverbanks are lower with gentle angles and multiple ages of floodplain trees, indicative of frequent hydrologic connection.

Figure 2. In the transition to the delta, riverbanks are lower with gentle angles and multiple ages of floodplain trees, indicative of frequent hydrologic connection.

At the transition into Lake Sakakawea headwaters banks are replaced by wide mudflats and open water.

Figure 3. At the transition into Lake Sakakawea headwaters banks are replaced by wide mudflats and open water.

The effect of the lake on river processes is quite evident. Upstream near Fort Peck Dam, the river banks are high, and often bare and eroding, indicating that the channel is incising. Moving downstream through the delta and headwaters, the bank height decreases, sediment deposition becomes apparent, and habitats become more complex. A big difference is the presence of gently sloping banks and different ages of floodplain willows and cottonwoods, indicating relatively frequent access of water to the floodplain. Floodplain connectivity is generally associated with high ecosystem productivity.

Reference:
Guy, C.S., Treanor, H.B., Kappenman, K.M., Scholl, E.A., Ilgen, J.E., and Webb, M.A.H., 2015, Broadening the regulated-river management paradigm: A case study of the forgotten dead zone hindering pallid sturgeon recovery: Fisheries, v. 40, no. 1, p. 6–14. 10.1080/03632415.2014.987236.

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

Steady Flows and Collaborative Science

By Robb Jacobson 7/6/2016

One of the key components to the Upper Missouri River Pallid Sturgeon Drift Experiment (see previous blog entry Pallid Sturgeon Free Embryo Drift Experiment Starts) was steady release of flow from Fort Peck Dam. Usually this time of year, releases cycle daily to follow electrical demand. Those so-called peaking cycles would have made the drift experiment more difficult to carry out and much more difficult to evaluate. The effect of the steady flow releases can be seen in a graph of water stage at the US Geological Survey streamflow gaging station just downstream from Fort Peck dam (figure 1).

 

Figure 1: Water-surface stage just downstream from Fort Peck Dam, showing typical peaking flows and steady flows held during the drift experiment.

Figure 1: Water-surface stage just downstream from Fort Peck Dam, showing typical peaking flows and steady flows held during the drift experiment.

 

In the weeks before the experiment, stages varied by about a foot whereas during the experiment flow releases resulted in fluctuations of less than 0.15 foot. The collaborators on the Drift Experiment are very grateful for the assistance of the U.S. Army Corps of Engineers Missouri River Basin Water Management Division and the Western Area Power Administration in keeping flow releases steady during the duration of the experiment.

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

Velocity Measurements in Support of the Drift Study

By Robb Jacobson and Susannah Erwin

One of the key components of the Upper Missouri River Pallid Sturgeon Drift Study is the collection of detailed water-velocity information. Water velocities are used to calibrate the advection-dispersion model (see previous blog entry Models and baby fish – digits, dye, particles, and biological reality) and to develop understanding of how channel form may affect transport and retention of pallid sturgeon free embryos.

We use boat-mounted acoustic Doppler current profilers (ADCP) to measure 3-dimensional velocity fields in transects oriented across the channel (figures 1 and 2). Positioning and navigation are provided through differentially corrected global positioning systems (GPS) that allow us to collect data in precise, pre-determined locations. The velocity data quantify the average velocity as well as the cross-sectional variation in velocity. Cross-sectional variation indicates where a river reach is likely to transport or retain dispersing free embryos (the life stage from hatch through first feeding).

ADCP_Boat1

Figure 1: A U.S. Geological Survey hydroacoustic survey boat measures velocity profiles on the Upper Missouri River.

 

Figure 2: Research hydrologist Dr. Susannah Erwin and hydrologic technician Brian Anderson inspect ADCP data on the Upper Missouri River.

Figure 2: Research hydrologist Dr. Susannah Erwin and hydrologic technician Brian Anderson inspect ADCP data on the Upper Missouri River.

The original sample design was to measure velocities at intervals along 221 miles of the Missouri River while the pallid sturgeon free embryos dispersed downstream, but river conditions have shown that we couldn’t traverse long sections of the river as rapidly as planned (see previous blog entry Boating the Upper Missouri River is not for the faint of heart). We revised our sampling design on the fly to emphasize detailed data collection in the reach upstream from Wolf Point, Montana, to support analysis of the dye trace component (see previous blog entry Missouri River Dye Trace Experiment to Support Understanding of Free Embryo Drift). From Wolf Point Montana to Lake Sakakawea we intend to provide a statistical subsample of the river (figure 3). Time is a constraint because we need to complete data collection while the US Army Corps of Engineers and Western Area Power Administration maintain steady releases from Fort Peck Dam.

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

Figure 3. Map showing the Upper Missouri River study area.

The statistical subsample is intended to quantify the variation in channel condition and velocity distributions that exist along the Upper Missouri River. Complex and wide reaches are expected to have more variable velocity distributions (figure 4) and more retention potential compared to straight, narrow reaches (figure 5).

Figure 4: Cross section of velocity collected via ADCP at RM 1702 showing variable velocity conditions in a complex reach of the Upper Missouri River.

Figure 4: Cross section of velocity collected via ADCP at RM 1708 showing relatively uniform velocity conditions in a less-complex reach of the Upper Missouri River.

Figure 5: Cross section of velocity collected via ADCP at RM 1708 showing relatively uniform velocity conditions in a less-complex reach of the Upper Missouri River.

Posted in Early life history, Methods, Upper Missouri and Yellowstone Rivers |

Night sampling for pallid sturgeon free embryos (The Fish Don’t Sleep and Neither Do We)

By Robb Jacobson and Aaron DeLonay

The sample design for the Upper Missouri River Pallid Sturgeon Drift Experiment depends on nearly around-the-clock sampling for free-embryos, the life stage from hatch to the initiation of feeding.  It can be a grueling process under the best of conditions, but for some of the crews there is the added complication of sampling at night.  The challenges of wind, rain, and swarming insects are intensified in the chill of a dark Montana night.

The night sampling effort starts at about sunset – 8 pm in this part of Montana in the summer – and continues 12 hours until crews are relieved the next morning (figure 1).  The crews transit to the pre-selected sampling sites before it gets too dark to avoid grounding on sandbars (see previous blog entry Boating the Upper Missouri River is not for the faint of heart).

Figure 1. USGS fish biologists launch at sunset on the Upper Missouri River for a night of sampling for pallid sturgeon free embryos.

Figure 1. USGS fish biologists launch at sunset on the Upper Missouri River for a night of sampling for pallid sturgeon free embryos.

Sampling requires winching a pair of heavily weighted, very fine-mesh nets (in figure 2) to the bottom of the Missouri River for a 10-minute collection, then winching it back up, emptying the contents of the net into a shallow sorting pan, and then sending the nets down again as quickly as possible.  The nets sample just above the bottom of the river and collect a large amount of detritus and organic matter. The crew quickly picks through the contents of the nets for free-embryo sturgeon and experimental beads.  The free embryos are counted and retained for genetic analysis while the number and color of beads are recorded.  The up and down cycle of the nets repeats all night.

Figure 2. USGS fish biologist Dr. Pat Braaten and student contractor Garrett Cook inspect contents of a larval fish net during night sampling on the Upper Missouri River.

Figure 2. USGS fish biologist Dr. Pat Braaten and student contractor Garrett Cook inspect contents of a net during night sampling on the Upper Missouri River. (photograph by Aaron DeLonay, U.S. Geological Survey)

 

It’s an intensive and strenuous process, and a bit eerie working from the light of headlamps while anchored in the middle of the river (figure 3).  In this type of sampling there are many net hauls that have zero free embryos or beads, so the rewards are not always immediate. The zero catches are important, however, because they indicate that the experimental release has not yet reached a site, or that all of the free embryos have passed.  When the first free embryos and beads show up in the samples (figure 4), the shouts of success carry in the night from one headlamp to the next, and across the river to the companion boat anchored in the darkness—then the night is not so dark, nor as cold, as it was before the crews found what they were looking for.

Figure 3. USGS biologist Dave Combs searches through net contents for larval fish during night sampling on the Upper Missouri River.

Figure 3. USGS biologist Dave Combs searches through net contents for free embryos during night sampling on the Upper Missouri River.  (Photography by Aaron DeLonay, U.S. Geological Survey)

 

 

Figure 4. Typical contents of a net deployment showing larval fish, possibly pallid sturgeon (at tip of forceps).

Figure 4. Typical contents of a net deployment showing a fish free embryo, possibly pallid sturgeon at the tip of forceps.  (Photograph by Aaron DeLonay, U.S. Geological Survey)

 

Posted in Early life history, Methods, Upper Missouri and Yellowstone Rivers |

Models and baby fish – digits, dye, particles, and biological reality

By Robb Jacobson and Ed Bulliner

The Upper Missouri River Pallid Sturgeon Drift Study is ultimately about providing sound scientific information for smart decisions. The decisions relate to how to manage this large river to help recover the endangered pallid sturgeon, or at least to avoid doing additional harm. The Missouri River Recovery Management Plan (http://moriverrecovery.usace.army.mil/mrrp/f?p=136:70) has been developing new sources of science information to address how this can be done.

A prominent hypothesis for the lack of pallid sturgeon population growth in the Upper Missouri River is that there is insufficient drift distance downstream from Fort Peck dam. This idea holds that there is not enough river to allow for development of swimming and foraging capability for the  drifting sturgeon free embryos (the period from hatch until the initiation of feeding) before they are swept into Lake Sakakawea where they may succumb to various causes of mortality, especially the threat of very low dissolved oxygen in the lake.

Dr. Craig Fischenich and colleagues in the US Army Corps of Engineers have developed a computational model – an advection/dispersion model – that can be used to address how river-management decisions change available and required drift distance. It’s a state-of-the-art model, but like any model it has assumptions and estimates. One of the main motivations for the Drift Study is to test the assumptions and find ways to improve the model. The multi-objective structure of the study is meant to determine how well drifting sturgeon free embryos conform to the model assumptions.

Our dye-trace sub-experiment (see previous blog entry Missouri River Dye Trace Experiment to Support Understanding of Free Embryo Drift) is meant to evaluate key components of the advection/dispersion model, in particular how well it predicts transport of a purely passive substance. Early download of fluorometer data(figure 1) from sites within 13 miles of the release site indicate that the dye is moving somewhat faster and is less spread out along the river compared to initial model estimates. Ultimately, passive transport will be compared to free embryo transport to develop biological reality for the model.

Research hydrologist Dr. Susannah Erwin retrieves fluorometer from the Upper Missouri River to download dye trace data.

Figure 1. Research hydrologist Dr. Susannah Erwin retrieves fluorometer from the Upper Missouri River to download dye trace data.

An important part of the model is the longitudinal dispersion coefficient that measures how particles spread out as they travel down the river. By varying that coefficient we can calibrate the model to more exactly replicate actual conditions. The comparisons between model results in red and dye trace data in blue, before (figure 2) and after calibration (figure 3), show the importance of the dye data. Final calibration of the model will require assessment of a lot more data, but initial calibrations have proven useful in determining where and when fish biologists should sample for pallid sturgeon free embryos during the study.

Figure 2. Comparison between initial model predictions (red) and dye-trace data (blue) about 12 miles downstream of dye injection site.

Figure 2. Comparison between initial model predictions (red) and dye-trace data (blue) about 12 miles downstream of dye injection site.

Figure 3. Comparison between calibration model results (red) and dye-trace data (blue) about 12 miles downstream of dye injection site.

Figure 3. Comparison between calibration model results (red) and dye-trace data (blue) about 12 miles downstream of dye injection site.

Posted in Early life history, Technology, Upper Missouri and Yellowstone Rivers |

Boating the Upper Missouri River is not for the faint of heart

By Robb Jacobson

The Upper Missouri River is mostly left to its own devices, allowed to migrate as it pleases. As a result, the river provides complex habitat that may lead to retention and growth of larval pallid sturgeon. The complexity is also vexing for boat drivers because it means that opportunities to get stuck on sandbars are around every bend.

Figure 1.  U.S. Geological Survey hydraulic habitat assessment boat in not enough water.

U.S. Geological Survey hydraulic habitat assessment boat in not enough water.

The boat of choice has an aluminum hull with a jet prop. On plane, these boats generally draft less than a couple of inches. Problems crop up when the water is shallower than that or the driver picks the wrong route in complex channels. The sandbars have a tendency to grab hard and hold fast. Getting a stranded boat off of a sandbar can require brains and brawn.

Figure 2: National Agriculture Imagery Program aerial photograph (2014) of part of the Upper Missouri River near Poplar, Montana. The river is flowing from left to right. The complex channel may promote retention of boats as well as drifting pallid sturgeon larvae.

National Agriculture Imagery Program aerial photograph (2014) of part of the Upper Missouri River near Poplar, Montana. The river is flowing from left to right. The complex channel may promote retention of boats as well as drifting pallid sturgeon larvae.

Knowing the river and being able to read the water are key. Using GPS and digital aerial photography, boat crews have even more ways to read the water, but we’ve found that images only two years old can be inaccurate in places where the river is especially active.

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