Kimberly Chojnacki

A USGS scientist inventories his equipment at the Columbia Environmental Research Center before embarking on the trip to Montana for fieldwork.

A biological science technician prepares the swim chambers to assess the swimming abilities of young pallid sturgeon.

A biological science technician collects pallid sturgeon free embryos from the sampling nets in the experimental streams at the Columbia Environmental Research Center.

Biological science aid, Marlee Malmborg, examines and records the viability of pallid sturgeon eggs at the Columbia Environmental Research Center.

Pallid sturgeon free embryos on the day of hatch, approximately 8-9 mm (about 0.33 of an inch) in length.

Developing pallid sturgeon embryo.

Newly hatched pallid sturgeon free embryo.  On average, pallid sturgeon hatch between 7 to 9 millimeters (about 0.25 to 0.35 inch).

Well-developed pallid sturgeon embryos can be seen approximately four days after fertilization. 

The neural plate or primitive streak of developing pallid sturgeon embryos can be seen 2 days after fertilization. 

Pallid sturgeon embryos approximately 8 hours after fertilization.

Pallid sturgeon larvae at 14 days post hatch. On agerage, pallid sturgeon transition to active feeding at approximately 16 to 18 millimeters (about 0.7 inch).

Pallid sturgeon free embryo at 2 days post hatch.  At two days after hatching the free embryos are generally 9 to 11 millimeters (0.35 to 0.45 inch).

Lake sturgeon free embryos at 3 days post hatch.  Free embryos at this stage have only a rudimentary mouth, their pectoral fins are only beginning to develop, and they rely on a large yolk sac for food. 

Newly hatched lake sturgeon free embryos.  Sturgeon embryos hatch without well-developed eyes, mouth, or fins and rely on a large yolk sac to fuel rapid early development.

One of six experimental stream segments used to study the dispersal of free embryo sturgeon at the Columbia Environmental Research Center.  The stream segment is 5 meters long and 0.5 meters wide, and is filled with cobble-sized rock to a depth of 12 centimeters.  Streams are covered during studies.

Pallid sturgeon free embryos preserved at 3 days post hatch.  Free embryos at this stage have only a rudimentary mouth, their pectoral fins are only beginning to develop, and they rely on a large yolk sac for food. 

Flood waters of the Missouri River and its tributaries cause road closures.

Woody debris is picked up and carried downstream by the rising waters of the Missouri River in Jefferson City, Missouri.

Fertilized pallid sturgeon eggs become sticky and adhere to gravel substrate.  

Fertilized pallid sturgeon eggs are gently dispersed over the gravel substrate.  The PVC pipes are used to support a canopy of shade cloth to more closely mimic the muddy depths of the Missouri River. 

The quality of pallid sturgeon eggs is verified under the microscope prior to fertilization.