While we are far from Washington, DC, we have our own form of the bipartisan Gang of Eight; eight reproductive pallid sturgeon, fitted with radio telemetry tags, and ready to spawn this spring. Four of these individual are currently located in the Lower Missouri River upstream of Rulo, Missouri confluence, and four are located downstream between St. Joseph, Missouri and Boonville, Missouri.
PLS11-016, PLS11-017, PLS11-018, and PLS11-020 are all female pallid sturgeon from the upper Lower Missouri River study segment released in reproductive condition from the conservation augmentation program during spring 2011, but that is where the similarities end. Females PLS11-016, PLS11-017, and PLS11-020 were not intensively tracked during spring 2011; fortunately each of these fish were also implanted with data storage tags (DST) which record depth and temperature at 15-30 minute intervals. These data allow us to examine behavior of individuals during periods that we would otherwise be unable to document and, in this case, give some indication of spawning location. By comparing various temperature data between the Platte and Missouri Rivers we were able to infer that PLS11-016 and PLS11-020 likely spawned in the Platte River, while PLS11-017 spawned somewhere in the mainstem of the Missouri River (see previous blog entry “Where Are You When I’m Not Looking?”). PLS11-018, on the other hand, was intensively tracked but exhibited limited reproductive behavior, remaining relatively stationary for more than a month. During June 2011, biologists targeted PLS11-018 for reproductive evaluation, which revealed that she had failed to spawn and her grey, mushy eggs were being reabsorbed. Two years later all four are ready to spawn again.
The four reproductive pallid sturgeon in the downstream reaches of the Lower Missouri River have little in common. Female pallid sturgeon PLS11-004 was initially captured and implanted during March 2011 in non-reproductive condition. In the fall of 2012 she was targeted for recapture when she moved more than 100 miles upstream. Ultrasound evaluation to assess reproductive condition revealed that she was reproductive and would likely attempt to spawn during spring 2013. PLS08-035 is a female pallid sturgeon initially implanted during May 2008 in non-reproductive condition after being used as broodstock in the population augmentation program at Blind Pony State Fish Hatchery. During the nearly five years of subsequent observations she has been recaptured and her reproductive condition re-evaluated during 2010, 2011, and 2012. For the first four years she remained non-reproductive and relatively stationary. That is, until October 2012, when ultrasound techniques revealed that she was reproductive and would likely spawn during spring 2013. Two new fish joined the Comprehensive Sturgeon Research Project, PLS13-001 and PLS13-002, rounding out the Gang. PLS13-001 is a hatchery-reared, female pallid sturgeon initially captured and implanted April 2013. Biologists were able to readily identify this fish was of hatchery origin by the presence of numerous tags including visual implant elastomer and coded wire. Male pallid sturgeon PLS13-002 was initially captured and implanted April 2013. Since implantation PLS13-002 has moved more than 40 miles upstream.
Biologists are hoping that this Gang of Eight will collaborate to reveal important new information on reproductive ecology of the pallid sturgeon.