Science Center Objects

June 28, 2016 

by Kimberly Chojnacki

On Monday afternoon, June 27, the collaborating scientists of the Missouri River Pallid Sturgeon Free Embryo Drift Study delivered over 700,000 one-day post hatch (dph) pallid sturgeon to the Upper Missouri River. The drift experiment has been over a year in the making and has been completely dependent on the ability to produce a statistically large number of newly hatched pallid sturgeon.  Through the concerted effort of Rob Holm and staff at the U.S. Fish and Wildlife Service, Garrison Dam National Fish Hatchery, 7 reproductive females and 5 males were synchronized to bring off the mass hatch. The day-old sturgeon were then trucked from Garrison to the Upper Missouri River, about 2 miles downstream of the Milk River Confluence (see previous blog entry Pallid Sturgeon Free Embryo Drift Experiment Starts) by U.S. Fish and Wildlife personnel (figure 1).

Distribution of free embryos to boats in preparation for mass release.

Figure 1. Distribution of free embryos to boats in preparation for mass release.

(Public domain.)

Once the tiny fish were acclimated to the ambient water temperature, they were released in the river to track their downstream dispersal (figure 2).  A small armada of sampling boats has been mobilized to capture these fish as they drift down the river over the next week. Ultimately, the results of this experiment are intended to show how the fish spread out in the river, how far they disperse, and whether they are retained in route.

Simultaneous mass release of 700,000 free embryos from boats distributed across the channel of the Upper Missouri River.

Figure 2. Simultaneous mass release of 700,000 free embryos from boats distributed across the channel of the Upper Missouri River.

(Public domain.)

The downstream sampling effort has been spearheaded by Dr. Pat Braaten, U.S. Geological Survey, and Dave Fuller and Tyler Haddix of Montana Fish Wildlife and Parks.  They are joined by a navy of fisheries biologists from U.S. Geological Survey, Montana Fish Wildlife and Parks, U.S. Fish and Wildlife Service, and Nebraska Game and Parks Commission. The sampling will continue – night and day – for as many as 7 to 9 days until it appears that all fish have been transported to Lake Sakakawea or have been retained in supportive habitats.  The samplers are especially grateful to the U.S. Army Corps of Engineers and the Western Area Power Administration for arranging to keep flows steady during the experiment.