After 5 to 15 minutes in the water column, the sampling nets are brought back to the surface. The samples are then emptied into pans and scientists then search for “biological gold,” specifically any larval fish that could be sturgeon. To prevent anylarval pallid sturgeon being missed, all larval fish belonging to the Acipenseridae family (sturgeon and paddlefish) are preserved in alcohol. These larvae are then taken back to the office for further identification under a microscope.
During the three days of sampling that followed the spawning of PLS11-007, only one sturgeon larvae was captured on April 5. The larvae was determined to be newly hatched, approximately five to six days post fertilization.
Crews tracked female pallid sturgeon PLS09-011 to her spawning site a few weeks later (see previous post Spawn with the Wind), then subsequently collected larval samples for four days. It was determined, using microscopic evaluation, that there were as many as eight sturgeon larvae captured near this spawning site. These larvae were also newly hatched, approximately six to eight days post fertilization.
Ultimately, genetic testing will be required to determine if any of the larvae caught at either site are pallid sturgeon.
See previous posts Searching for a needle in a haystack, and Day old sturgeon caught in the Lower Missouri River for more information on 2011 larval sampling and catch.