Unprecedented Pallid Sturgeon Larval Drift Experiment
July 1, 2019
Scientists with the Columbia Environmental Research Center (CERC) collaborated with the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, Montana Fish Wildlife and Parks, and Southern Illinois University scientists in early July to carry out a larval drift experiment of unprecedented scale and complexity. The experiment involved the release of over 1 million, genetically distinct larval pallid sturgeon, ranging 1 to 5 days old. The experimental results are fundamental for calibrating biological-hydraulic models of drift and dispersal of larval pallid sturgeon on the Upper Missouri River, Montana. The dominant hypothesis for recruitment failure of the critically endangered pallid sturgeon on Upper Missouri River is insufficient drift distance between Fort Peck Dam and Lake Sakakawea.
The planning for the 2019 Upper Missouri River study was several years in the making. Data collection began in 2018 and continued through 2019 as USGS scientists spent weeks intensively mapping the depth, water velocity, and elevation of the sand bars and river banks along a 36 kilometer reach of the braided river between Wolf Point and Poplar, Montana where the experiment was to happen. The survey data will be used to create with high-resolution hydrodynamic and particle-tracking models to understand how downstream dispersing free embryo sturgeon are distributed through the reach, and how far and how fast they are expected to travel.
A year of planning meetings, data collection, broodstock collection, and hatchery efforts culminated in an early afternoon congregation on the north bank of the Missouri River near a boat ramp in Wolf Point, Montana. A half dozen boats and two dozen biologists received their final instructions while awaiting the truck from Garrison National Fish Hatchery laden with coolers packed with 80 bags of oxygenated water carrying free-embryo pallid sturgeon for the experiment. Upon arrival, coolers were loaded into boats, the boats moved out into the water and anchored across the width of the river. The fish in the coolers were slowly acclimated to the river temperature and when the signal was given all the boats simultaneously released the young sturgeon. In the end, the event went off without a hitch. Approximately 850,000 day-old and 225,000 five-day-old pallid sturgeon larvae were released into the waters.
Over the next week, 8 boats and as many as 2 dozen scientists and technicians will work around the clock exhaustively sampling to track the downstream transport and fate of the larvae to the headwaters of Lake Sakakawea near Williston, ND.