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 20th 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
In late February and March the Missouri River is a lonely place. Comprehensive Sturgeon Research Project boats from the USGS and the Nebraska Game and Parks Commission search the cold, still waters for the telltale chirp of a telemetry transmitter indicating that they have located the wintertime haunt of an adult pallid sturgeon. Few people visit the boats ramps or stop to ask the biologists what they are doing out on the Missouri River in the cold. Other boats are rarely sighted on the river during the coldest months of the year; however, it does not mean that our activities go unnoticed. Winter is a great time to observe wildlife along the river and concurrently provides an opportunity for wildlife to watch us. Whitetail deer and beaver move along the banks while bald eagles soar above, occasionally dipping down to the water surface to snatch a fish. On one Tuesday in March, a flock of ring-billed gulls rested along the river bank, jostling for the best position to view our biologists as they drifted a net with the icy current to capture a tagged sturgeon. Alerted to the spectacle, a turkey perched himself high on a rock dike above the river to assess the cause of the commotion. It is hard not to feel a little sense of added pressure when there are at least another 50 pair of eyes watching.
At the end of the day the biologists netted their fish. PLS11-010 was weighed and measured, and the tags she had carried for the last two years were replaced with new ones supplied with fresh batteries. The oocytes (developing eggs) inside her smooth abdomen are small and white, meaning she will not be ready to spawn this spring. Maybe next year will be her year.
Ring-billed gulls line a sand bar along the Missouri River to watch USGS boats fish for sturgeon.
A wild turkey perches on a rock dike in the Missouri River to get a closer look at USGS boats fishing for sturgeon.
By Aaron DeLonay
Freezing temperatures and low water levels have created significant ice flows in portions of the Lower Missouri River during winter months. These conditions have made boat ramps unusable for our partners with the Nebraska Game and Parks Commission (see photo below), hampering pallid sturgeon tracking efforts in the most upstream segments of the study area. Farther downstream, CSRP biologists located in Columbia, MO have been able to conduct their monthly river sweeps without difficulties arising from ice. Low water conditions; however, continue to restrict access to the river at several locations between Kansas City and St. Louis. In addition, shelf ice that forms along the banks of the river has made it difficult for CSRP biologists to retrieve submerged data loggers that monitor temperature throughout the year. For more information on how this past year’s weather conditions have affected our efforts on the Missouri River, see previous post “How Low Can It Go?”.
January 2013: Ice flows and low water levels have hindered pallid sturgeon tracking efforts in portions of the Missouri River. Pictured is a boat ramp located near Omaha, Nebraska. Photo courtesy of Josh Wilhelm of the Nebraska Game and Parks Commission.
January 2013: USGS biological science aid Jeff Beasley retrieves a temperature logger from the Missouri River near Decatur, NE. Several inches of ice were chipped away in order to gain access to the cable that secures the temperature logger to the bank.
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.
Last month, the Columbia Environmental Research Center (CERC) hosted a tour for Hickman High School’s biology club. Fifteen students from the high school located in Columbia, MO gathered at the CERC to learn about various research projects at the center and types of jobs available in fisheries science. Scientists from the branches of toxicology, ecology, and river studies spoke to the group on an array of topics including fish behavior, invasive species, acoustic telemetry, and sediment toxicity. In addition, students were able to discuss career options with ecologists, database managers, and research technicians.
Students from Hickman High School’s biology club ask questions during an educational tour at the Columbia Environmental Research Center (Columbia, MO). Photo by Terese Dishaw.
Biologists Hallie Ladd and Chad Vishy give a presentation about the comprehensive sturgeon research project to Hickman High School students.
October proved to be a busy and successful month for USGS Comprehensive Sturgeon Research Project biologists as four reproductive female pallid sturgeon were targeted and recaptured between river miles 359 and 599. Using a portable ultrasound device, scientists were able to determine that all four females were at a 4/5 reproductive stage (see photo below), indicating that these fish will be ready to spawn during the spring of 2013. Three of the reproductive females, PLS11-016, PLS11-017, and PLS11-018 were all initially implanted with telemetry devices in April of 2011. All three females were located downstream of Bellevue, Nebraska during last month’s river sweep. The fourth female, PLS08-035, was initially implanted in March of 2008 as a non-reproductive female. PLS08-035 was last located upstream of Kansas City, KS in late October. Biologists will continue to monitor the movements of these females with the hopes of documenting spawning behavior in the spring. For more information on this year’s reproductive females, see previous post “Thinking Ahead”.
Pre-spawn ultrasound image of reproductive female pallid sturgeon PLS11-016: the green arrow points to a ripe egg in the side view of the fish’s abdominal cavity.
With the fall season upon us, Comprehensive Sturgeon Research Project (CSRP) biologists are already beginning to think of next spring’s field season. During these cooler months, field crews are busy tracking and recapturing pallid sturgeon that they believe will become reproductive during next year’s spawning season. Several pallid sturgeon have been identified by scientists as “fish of interest” based upon past reproductive assessments and their movements throughout the Missouri River.
Pallid sturgeon PLS10-017 was originally implanted with telemetry devices in the spring of 2010 as a non-reproductive female. In June of 2012, this female was recaptured and reimplanted with telemetry devices with fresh batteries at river mile (RM) 543.7 near Peru, Nebraska (for more information on data storage tags see the previous post “Where Are You When I’m Not Looking?”). At that time, she had small, white-gray eggs that were visible in the ultrasound and through the small incision made during surgery. Field crews hope to recapture PLS10-017 this fall to determine if her eggs have developed to the point where they can confidently predict that she will likely spawn in the spring of 2013. PLS10-017 was last located at RM 554.9 during August’s river sweep.
Female pallid sturgeon PLS11-018 was originally captured, implanted with telemetry devices, and released near river mile 185 during the spring of 2011. Since then, tracking crews have located her on 25 different occasions throughout the Missouri River. PLS11-018 was found at RM 341.9 in late March of 2012 and was last located at RM 602.6 near the end of September. This steady upstream movement could indicate that PLS11-018 may be getting an early start on a spring spawning migration. Similar to PLS11-018, female pallid sturgeon PLS08-035 has been moving up the Missouri River. From her initial capture date in 2008 through January 2012, this female has moved only 2.5 miles. Starting in May of 2012, PLS08-035 has moved upstream approximately 85 miles. Could she also be getting a head start on a spring spawning migration? Biologists will be targeting these females this fall to find out.
Telemetry locations of two female pallid sturgeon: PLS11-018 (top) and PLS08-035 (bottom). The steady upstream movement displayed by both fish may indicate an early start to spring spawning migrations.
USGS biologists captured a single drifting free-embryo sturgeon in their nets while sampling the Lower Missouri River near the confluence with the Mississippi River on August 22, 2012 (see photo below). The tiny sturgeon was barely a half of an inch long. Based upon developmental characteristics, biologists determined that it hatched less than 5-7 days before it was captured. This find was unexpected and somewhat puzzling as shovelnose and pallid sturgeon in the Lower Missouri typically spawn between April and June at water temperatures ranging from 60 to 72º F.
Why was this little sturgeon born in the middle of August at water temperatures exceeding 82º F, nearly two months after sturgeon should have stopped spawning? Could this be natural variation in the population of sturgeon in the Missouri River or is it a sign that something unusual or unexpected is occurring? Is it possible that this sturgeon embryo was spawned in the cool waters below the dams far upstream or in some shaded tributary and drifted down into the warm and muddy Missouri? Have modifications to the Missouri River altered the timing of sturgeon spawning; extending the spawning season? Or could one of our sturgeon species have more than one spawning strategy – are there spring spawning sturgeons and fall spawning sturgeons of the same species in the Missouri River? This little enigmatic sturgeon has caused much speculation among the biologists who continue to sift the waters for drifting larval sturgeon. Only time and continued sampling will help to unravel the puzzle.
A free-drifting sturgeon embryo was captured in the Lower Missouri River in late August. This was unexpected discovery as most sturgeon in the Lower Missouri River spawn in the spring.
By Aaron DeLonay
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