It may seem a bit early to ask this question, but the spring spawning season is never far from CSRP biologist’s minds (see previous post Thinking Ahead). Preparations for the 2014 spring season started early in the fall when crews began locating tagged female pallid sturgeon that they believed would become reproductive in the spring. Once a targeted female had been located, biologists drifted trammel nets over her location until the fish became entangled in the net and could be pulled into the fishing boat. The fish was then placed into an aerated holding tank where biologists used non-invasive ultrasound techniques to check for the presence of developing immature eggs (oocytes). Any females determined to have oocytes will be intensively monitored in the spring of 2014 in the hopes of determining her spawning location.
During the week of September 16th, CSRP biologists recaptured and evaluated three female pallid sturgeon (PLS11-019, PLS10-029, and PLS12-002) expected to be in reproductive condition this coming spring. PLS11-019 was first implanted with a telemetry transmitter in 2011 and released near river mile 717.1 near Sloan, IA. PLS11-019 is expected to spawn for the second time in 2014 and will be tracked by biologists in the CSRP project. She was first documented to have spawned in the Missouri River during the spring of 2012 between river miles 700 and 714. Determining how often pallid sturgeon females spawn, and if they return to the same places to spawn time after time, is critical information for biologists.
PLS10-029 was first telemetry tagged in the spring of 2010 near river mile 563.7. She was last in reproductive condition in the spring of 2012 and is also ready to spawn again after only 2 years. Tracking efforts and retrieved data storage tag (DST) data have shown her to make spring migrations up the Platte River in both 2011 and 2012 (See previous post “Where Are You When I’m Not Looking?”). It is likely that PLS10-029 spawned in the Platte River in 2012. Since then she has spent most of the last two years between Plattsmouth and Bellevue, NE. Biologists expect that she will again migrate up the Platte River in the spring of 2014.
PLS12-002 was first telemetry tagged in the fall of 2012 near river mile 576.2. Based on the presence of a coded wire tag, biologists were able to determine that PLS12-002 was originally produced in a hatchery. PLS12-002 was last located at river mile 513 during October 2013’s river sweep. PLS12-002 is evidence that hatchery-produced pallid sturgeon can grow and reach reproductive condition in the contemporary Missouri River. Whether hatchery progeny will spawn with other pallid sturgeon at the same spawning locations, and successfully contribute to the recovery of the species has not yet been established. Biologists are hopeful that fish such as PLS12-002 will provide that needed insight. All three females will again be targeted for recapture in the spring of 2014 for evaluations of reproductive readiness.