An Early Spawning Recorded

Female pallid sturgeon PLS11-007 was initially implanted with telemetry devices in April, 2011. She was in non-reproductive condition with small white eggs, indicating that she may be nearing reproductive condition. From April until mid-September 2011, she was relocated on 15 occasions, in areas less than one mile apart. Since she was carrying small eggs in the spring, biologists targeted her for reproductive evaluation during the fall of 2011 (see previous post Head Start).  Biologists were able to recapture PLS11-007 and determined that she was in reproductive condition and would likely spawn in the spring of 2012.  From mid-September to mid-November 2011 she steadily moved upstream approximately 100 miles.  From mid-November 2011 through mid-March 2012 she was relocated on seven occasions within approximately 5 river miles. 

By the end of March, she had moved upstream approximately 25 miles and exhibited characteristic spawning behavior.  She seems to have spawned  in over 22 feet of water, on an outside bend revetment (large rock used to stabilize the river bank) on April 30th and 31stDIDSON technology was used to obtain imagery revealing multiple sturgeon in the area.  Biologists watched PLS11-007 using sonar as she finished spawning and moved off into the main river channel alone.  She was recaptured a short distance downstream on April 3rd by biologists, and was determined to have completely spawned.  Notably, this spawning event is approximately four to six weeks early compared to other spawning events that we have recorded!

Figure 1. Telemetry locations of female pallid sturgeon PLS11-007 from April 5, 2011 to April 3, 2012.

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