Comprehensive Sturgeon Research Project

Pallid sturgeon and their close relatives, the shovelnose sturgeon, are not the only sturgeon in the Missouri River. USGS and state research biologists sampling for pallid sturgeon in the Missouri River occasionally collect specimens of the “other” sturgeon species, the lake sturgeon (Photo 1—lake sturgeon). Lake sturgeon live in the large lakes and rivers of the mid-continental United States and Canada. They can live more than 100 years, grow to more than 2 meters (6 feet) or 90 kilograms (200 pounds), and may take more than 20 years to reach reproductive maturity. Similar to the pallid sturgeon, lake sturgeon populations declined dramatically as North America entered the 20^th century. Overfishing, dam construction, channelization of large rivers, and unchecked pollution eliminated or severely reduced most populations. The lake sturgeon was nearly extirpated from the Missouri River by 1910. The species was listed as a State Endangered Species in Missouri in 1974. In 1984 the Missouri Department of Conservation began the long, but sustained effort to return the species to Missouri waters. The heavily built lake sturgeon, with its short conical snout (Photo 2—lake sturgeon head) is caught on trotlines while sampling for pallid sturgeon. Information about each captured sturgeon and the hatchery tags they carry are reported to the Missouri Department of Conservation to aid their efforts in monitoring populations and tracking progress towards recovery. Some of the lake sturgeon stocked early in the State’s recovery program are now more than 30 or 40 pounds and are searching for a suitable place to spawn.

Check out the Missouri Department of Conservation’s Lake Sturgeon webpage to learn more about the State’s efforts to recover the “other” Missouri River sturgeon.  And if you happen to be out on the Missouri or Mississippi River, or one of their tributaries and you are fortunate to catch a large lake sturgeon, your local Missouri Conservation Department office would like to hear about it.

Photo 1. A USGS Biologist holds a juvenile lake sturgeon caught on a trotline while sampling for pallid sturgeon. The young lake sturgeon had a PIT tag that identified it as a fish previously captured and released by the Missouri Department of Conservation.

Photo 2. Compared to the pale, slender pallid sturgeon, the dark brown or olive grey lake sturgeon has a stocky build and a conical shaped snout. It is commonly referred to as a “rubbernose” sturgeon.

By Aaron DeLonay

CSRP biologists working on the Missouri River have no shortage of challenges; each year brings a fresh crop.  In 2011, biologists were dealt record high flows that persisted through summer making work on the river trying.  Field crews found it necessary to employ tandem tracking, using two boats, one on each side of the river, to effectively detect telemetered pallid sturgeon (see blog entry “Sometimes It Takes Two”).  In 2012, spring came early and water temperatures increased quickly, reaching suitable spawning temperatures (15°C) 4 to 6 weeks earlier than normal.  For CSRP biologists that meant the discontinuation of spring sampling and scrambling to prepare for a fast approaching spawning season (see previous blog entry “An Early Spawning Recorded”).  As summer wore into fall, substantial drought and subsequent low river levels limited access and presented a new set of logistical issues (see previous blog entry “How Low Can It Go?”).  This year, the uncertainty of federal budget sequestration limits CSRP staffing and travel, yet again testing our creativity and versatility.  However, CSRP biologists are an unwavering sort and will meet the coming challenges of 2013  with determination and dedication.

Mean discharge and temperature of the Missouri River near Hermann, MO. The dashed bars represent the approximate threshold for pallid sturgeon spawning. In 2012, spawning temperatures were reached in March. Previous spawning events typically have occurred later in the springtime, from late April to early May.

Completed with contributions by Kimberly Chojnacki and Jake Faulkner

According to the National Oceanic and Atmospheric Administration (NOAA), 2012 marked the warmest year on record for the contiguous United States.  The year began with above-average temperatures and limited snowfall followed by an unusually warm spring.  In turn, the warm spring resulted in an early start to the 2012 growing season in several places, which increased the loss of moisture from soil.  These elements, in combination with other factors, helped lay the foundation for the drought conditions experienced by a significant portion of the U.S. in 2012.

The extreme temperatures and drought have had noticeable impacts on the Missouri River. In March of 2012 water temperatures in the Lower Missouri warmed  quickly, reaching spawning temperatures for many fish species far earlier than usual.  The following month, Comprehensive Sturgeon Research Project (CSRP) biologists documented a pallid sturgeon spawning event that was approximately four to six weeks early compared to previous spawning events (See previous posts “Rising Temperature” and “An Early Spawning Record”).  Drought conditions have continued and resulted in low river levels into 2013. Unusually low river conditions  have the potential to create hazardous situations for our tracking boats through the winter including exposed sand bars and rock formations, ice flows, and unusable boat ramps.  With this in mind, CSRP biologists have been making extra efforts to ensure crew safety by monitoring river and weather conditions, closely.

The drought conditions that affect the Missouri River Basin will likely persist through winter and into spring, but CSRP biologists will be ready for whatever the weather brings.

January 2013: CSRP biologists traveled along the Missouri and Mississippi rivers in search of usable boat ramps from which to launch their tracking boats. Pictured is a ramp located on the Mississippi River near Cape Girardeau, MO.

January 2013: CSRP biologists traveled along the Missouri and Mississippi rivers in search of usable boat ramps. Pictured is a ramp on the Mississippi River near Grand Tower, IL. The photographer is standing at the river’s edge, looking up the boat ramp, from far below where boats are normally launched.

The Missouri River is large, muddy, and turbulent. The complexity of the river can make it nearly impossible for scientists to observe the complete pallid sturgeon life cycle in the wild. Therefore, several studies concerning the early developmental stages of pallid sturgeon are conducted in controlled laboratory settings at the Columbia Environmental Research Center (CERC). This summer, biologists began to study what happens to sturgeon embryos after they hatch in the river.

Eggs collected from pallid sturgeon spawned in hatcheries were fertilized and gingerly placed onto an artificial rock substrate. The tiny, three millimeter eggs are very sticky just after fertilization and adhere to the surfaces of the rocks, even in a current (See photo below). The rock substrates with the eggs attached were placed into an artificial laboratory stream that mimicked the conditions where the eggs might develop in the Missouri River. Though the laboratory stream system could not achieve the highest velocities or provide the complexity of hydrologic environments found in the Missouri River, its simple design could provide scientists insight into the mysterious world of the first days of the pallid sturgeon.

Eggs collected from pallid sturgeon spawned in hatcheries are placed onto an artificial rock substrate. Pallid sturgeon eggs are extremely sticky after fertilization and adhere to the artificial substrate, even in a current.

After six days of watching the embryos develop and wiggle inside their thin eggshells, the eggs began to hatch. Some of the little sturgeon burst from their eggs head first and disappeared in the blink of an eye–swept away in the current of the artificial stream. Others struggled a bit, emerging tail first and wiggling their way to freedom. Interestingly, most of the freed embryos were rolled off the rocks and into the substrate by the current. Click HERE to view a video of the hatching.

Biologists observed the larval sturgeon and recorded every movement that they made around the clock using infrared digital cameras that can see the tiny fish under water, even in the dark. The young pallid sturgeon developed quickly. After several days their fins began to grow and they were strong enough to orient themselves and swim against the current. In a few more days the larvae began to resemble miniature sturgeon, settled to the bottom of the stream, and moved freely throughout the water in search of food. Biologists measured the changes in development and behavior of the small sturgeon hoping to learn how they have adapted to control their downstream dispersal and eventually end up in places where they can find food and protection from predators. Most young sturgeon do not make it. Only a fraction of one percent of all sturgeon eggs hatch and survive the first year of life. Understanding what young sturgeon do in the first weeks of life may help biologists to find ways to increase their survival just a fraction of a percent more. That little bit more, may make all the difference to sturgeon populations in their dark and mysterious world.

Completed with contributions by Aaron DeLonay, Patty Herman, and Diana Papoulias