Spawn with the Wind

The upstream migration of female pallid sturgeon PLS09-011 continued on April 18th and 19th (see previous posts Going, going…).  However, she disappeared for the next few days until being located more than 50 miles downriver from her previous location on April 25(fig. 1). 

Figure 1: Telemetry locations of female pallid sturgeon PLS09-011 from March 1 to April 27, 2012.


On April 26, she moved upstream approximately one mile.  To the surprise of researchers, she began moving up and down an outside bend revetment (large rock used to stabilize the river bank), which is behavior indicative of spawning.  Biologists Justin Haas, Brian Hoffman, Ryan Ruskamp and Erik Prenosil from the Nebraska Game and Parks Commission were able to maintain contact with PLS09-011 throughout the day, until about 3am the following morning. They recorded her movements as often as every fifteen minutes. 

Around midday on April 27, PLS09-011 moved out into the main channel of the Missouri River.  Crews from USGS then braved gale force winds (fig. 2) and high waves to successfully recapture this very valuable fish.  Research biologists were able to determine that this female had spawned.  

Figure 2: Windspeed map from on April 27, 2012.

Below is an image illustrating the weather conditions endured by tracking and recapture crews on April 27.  We certainly appreciate the dedication and tenacity of our devoted field crews! 

Figure 3: High winds cause waves to break over the bow of a USGS tracking vessel on April 27, 2012.

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