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.
June 21, 2017
Beginning in early June, four Comprehensive Sturgeon Research Project (CSRP) research crews from the Lower Missouri River packed up their equipment and travelled north to the Upper Missouri and Yellowstone Rivers in Montana. A telemetry tracking crew was deployed to record the movements of adult pallid sturgeon in the Yellowstone River, and to document when and where spawning occurs. The second crew was deployed to sample for Acipenseriformes (sturgeon and paddlefish) free embryos and larvae using fine mesh ichthyoplankton sampling nets. The third crew was deployed to record spawning behavior of pallid sturgeon using advanced sonar equipment. A hydrology research crew was deployed to characterize spawning habitat. Crews from the Lower Missouri River joined CSRP researcher, Dr. Pat Braaten, from the USGS Project Office in Fort Peck, Montana and biologists from Montana Fish, Wildlife and Parks (MFWP). Pat and his colleagues from MFWP have been tracking adult pallid sturgeon on the Upper Missouri River from Lake Sakakawea upstream to Fort Peck Dam, and up the Yellowstone River (see previous blog entry An Update From The Field: Preparing for the Yellowstone River Spawn). Later in the month, four additional CSRP scientists will travel to the Lower Yellowstone to carry out a dye-trace assessment of larval transport (Red Dye Study Will Examine Water Flow in Yellowstone River near Glendive, Montana). Studies of spawning and larval transport will wind up in early July while assessments of survival of pallid sturgeon hatched this year will continue through the fall.
An update from the field: Preparing for the Yellowstone River spawn
June 14, 2017
We have been tracking the pallid sturgeon research population (see Pallid Sturgeon Spawning Studies in the Yellowstone River Have Begun ) for the past several weeks under elevated flow conditions in the Yellowstone River. Aggregations of male pallid sturgeon from early May through early June were observed at a few locations in the Lower Yellowstone River, with some aggregations holding 10 or more males. Although early-season, pre-spawn male aggregations have been observed in previous years, these aggregations have typically persisted for only a few days. In contrast, aggregations this year have persisted for several days to more than a week. The function or purpose of these early-season male aggregations is not known. In addition to wild-origin male pallid sturgeon, a few hatchery-origin pallid sturgeon also have been observed within the aggregations. This observation suggests that hatchery-origin fish that are now approaching adulthood and sexual maturity may be expressing behaviors of their wild counterparts. Following the onset of higher discharges in recent days and the drifting debris fields (see photo), the male aggregations have disbanded and males are now scattered throughout much of the Lower Yellowstone River.
Spawn-candidate females have exhibited an array of pre-spawn behaviors to date that show similarities and differences to earlier investigative years. As observed in past years, reproductive females typically exhibit continued and extensive up- and downstream migration behavior prior to spawning and rarely hang out with the males during the pre-spawn period. So far this year, three spawn-candidate females have demonstrated the tendency to reside in close association with the male aggregations. The fourth female is more of a runner, tending to more closely match female behaviors of earlier years. However, as with the disbanding of the male aggregations in recent days under elevated flow conditions, the spawn-ready females may also change behaviors in response to the elevated flow conditions.
The pallid sturgeon pre-spawn framework is in place, and shortly will progress to the spawning stage. Discharge in the Yellowstone River is projected to increase to a maximum by mid-June, then decline. We expect that turbidity will increase then diminish, water temperature will continue to rise, and hormones circulating in the male and female pallid sturgeon will exert their control in dictating when spawning occurs. The exact date of spawning is not known, nor is the exact location. Will the males re-aggregate at one or more of their earlier aggregation locations to stake out the spawning patch, or will spawn-patch aggregations form at different locations – new spawning patches developed from reshaping of the river bed from the elevated flow conditions of recent days? These uncertainties will be answered in the upcoming weeks as crews track the males and females.
Pallid Sturgeon Spawning Studies in the Yellowstone River Have Begun
June 14, 2017
In early-May crews from USGS, Montana Fish, Wildlife and Parks (MTFWP), and U.S. Fish and Wildlife Service (USFWS) embarked on the dual task of capturing broodstock for the pallid sturgeon propagation program, and assessing females suspected to be in reproductive condition.
The cooperative efforts produced results as several male pallid sturgeon and one reproductive female –known as radio code 39 – were captured and transported to the USFWS Garrison Dam National Fish Hatchery. Code 39 was previously captured in 2014, implanted with a transmitter, and used in the 2014 spawning studies on the Yellowstone River (see previous entry A Spawning Recorded in the Yellowstone River). Female code 39 was targeted for capture and reproductive assessment in 2016, but was detected only once at a logging station and never captured. Her appearance this year made her a definite target for capture and assessment. As she was determined to be reproductive (based on presence of black eggs) and had never been used in the pallid sturgeon propagation program, she and her genetic information will join the males at Garrison for production of the 2017 year class of pallid sturgeon.
The team also established the cast of potential spawners for reproductive research in 2017. Two previously non-telemetered reproductive females were captured, implanted with telemetry transmitters, and subsequently will be the focus of spawning studies. Two previously telemetered females were captured and determined to be in reproductive condition. Collectively, the four females along with dozens of telemetered males comprise the research population for 2017. A few other females suspected to be in reproductive condition during 2017 have either tested negative for reproductive readiness or have not been located. The at-large females may eventually show up as well.
Just keep swimming
June 13, 2017
In parallel with stream-dispersal studies, another experiment was being conducted in the labs at the Columbia Environmental Research Center. Using the same families of fish as the stream studies, swim chambers were set up to directly test the swimming abilities of free-embryos and larvae. The chambers allow for measurement of behavioral responses to varying velocities.
The lab trials consisted of free-embryo and larval sturgeon of increasing age and developmental stage being placed in an 11” x 3” x 3” chamber where water velocities would be incrementally increased until the fish no longer maintained their position in the water. Velocities started at 3 centimeters per second and increased 1 centimeter per second every 2 minutes thereafter. Fish swimming behaviors were also monitored and recorded to identify where in the water column the fish swam and whether they chose to face into or with the current.
Trials were conducted with a minimum of 10 specimens beginning with one day old free embryos and continuing to 16 days after hatch exogenously feeding larvae. The specimens were preserved for analysis following their respective trials to allow scientists to compare their swimming abilities and behaviors to their development. Just as with the stream experiments, the shovelnose sturgeon trials were followed by trials with free-embryo and larval pallid sturgeon.
Back to work in the streams
June 13, 2017
The Comprehensive Sturgeon Research Project (CSRP) 2017 field season was initiated with stream experiments here on the USGS campus. Previous CSRP studies looked into the tendency of sturgeon free embryos to linger in substrates of different sizes at different ages (see Stream Studies Back in Action and Studies of Lake Sturgeon Free Embryo Dispersal Begin). This year, rather than using different substrates, the experimental streams were set up with sections of varying velocities. After release in the experimental streams, the sturgeon free embryos and larvae drifted through two areas of relatively-high velocity and two slow-moving pools. The objective was to see at what age the fish were able to hold their position in the water rather than simply drift – or if they appeared to do so at all.
Trials were conducted every three days beginning with one day old free embryos and concluding with 16 day old larvae. Subsequent trials were conducted with pallid sturgeon of the same ages to compare the behaviors between the two closely related species.
By studying the behaviors of the early life stages of sturgeon within the context of our ongoing drift modeling (see Missouri River Dye Trace Experiment to Support Understanding of Free Embryo Drift) and previous free-embryo releases (see Pallid Sturgeon Free-Embryo Drift Experiment Starts), we hope to get a better understanding of the challenges and necessary conditions during these crucial developmental stages.
Comprehensive Sturgeon Research Project, 2017
June 9, 2017
The Comprehensive Sturgeon Research Project (CSRP) blog has been late getting started this year due to distractions of a very busy season. The blog is resuming now with a variety of posts. Studies this season so far have concentrated on laboratory assessments of development of early-life stages of pallid sturgeon, including their susceptibility to sand abrasion and their ability to hold station in moving water. Field research has also started with deployment of a new, high-resolution multibeam bathymetric system to increase resolution for measuring important habitats in the Lower Missouri River. CSRP researchers are helping scientists with the Bureau of Reclamation and Montana Fish Wildlife and Parks with an adult translocation experiment around Intake Dam on the Yellowstone River, as well as tracking of reproductive adults to assess migrations and spawning. Blog entries on these studies – and more – will be found here in the coming months.
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