Where The Boys Are

For the past several seasons CSRP biologists have intensively and meticulously tracked female pallid sturgeon to their spawning locations.  All this attention on females is because biologists can easily tell when a female spawns by the presence or absence of eggs.  When the female is tagged with eggs, migrates, then stops, and is recaptured without any eggs it is easy to conclude that she must have spawned.  Knowing where these spawning sites are is critical to understanding why there are so few young pallid sturgeon being added to the population each year.  But finding the “spot” on the map where spawning happens is only part of the story.  What are the males doing while females are migrating upstream and what part do males play in when and where females stop to spawn?  Spawning locations are defined by where a female deposits her eggs, but which sex really chooses the spot on the map, and why?

For the first time in the Lower Missouri River, CSRP biologists documented a small aggregation of reproductive male pallid sturgeon this spring.  On May 22, 2013 CSRP biologists set out to recapture telemetered male pallid sturgeon PLS08-048, near the Platte River, Nebraska at rivermile 594.7.  Biologists were curious to know if the male was reproductive and ready to spawn with nearby females.  A trammel net was drifted over the tagged fish several times, but the targeted fish was not captured on that day.  Instead, four different male pallid sturgeon without telemetry tags were caught.  Three out of these four males were in reproductive condition at the time of capture.  The following day,  May 23rd, a fourth reproductive male pallid was captured just upstream of the male aggregation recorded the previous day.

CSRP researchers have previously documented loose aggregations of males in the Yellowstone River, North Dakota a few miles upstream of the confluence with the Missouri River (see previous post  Just One of the Guys).  These aggregations of males in the Yellowstone have occurred near suspected spawning locations.  Biologists are hoping to learn if male pallid sturgeon are selecting spawning locations early in the season before females with eggs arrive.  They want to know the factors that male sturgeon use to select spawning sites and whether or not females are selecting spawning sites using the same factors or if they are relying on the judgment of the males who have already arrived.  If biologists can determine which sex is selecting spawning sites, and what factors are preferred as “good” spawning habitat, then it is possible to determine how much spawning habitat is available and maybe predict spawning success.

CSRP Biologist Sabrina Davenport with a reproductive male pallid sturgeon. Two additional reproductive male pallid sturgeon were caught during the recapture effort near the confluence of the Platte and Missouri Rivers early in the spring of 2013.

Posted in Recapture |

A Rocky Start

If asked to describe the first few weeks of a baby pallid sturgeon’s life in the Missouri River, most biologists will tell you the embryos attach to a hard surface, develop, hatch, and enter the fast-flowing water to drift downstream.  Despite catching a very few free embryos over the last 10 years, no one has actually observed this phase of the sturgeon’s life cycle in the river.  Instead we’ve used scientific deduction and reasoning to come up with a plausible scenario of how a pallid sturgeon begins its life in the river.

Recently, however, laboratory observations of pallid behavior at these earliest stages, together with new data on post-hatch behaviors of other riverine sturgeons, have led to an alternative hypothesis to the hatch-and-drift paradigm.  Our flume studies of 2012 and 2013 have indicated that newly-hatched pallid sturgeon survive for only a few hours at water velocities > 0.10 m/s.  It isn’t until the sturgeon are 12 days old that they can survive at velocities of 0.23 m/s. 

How then can newly hatched pallid sturgeon survive velocities in the range of 1.5-3 m/s, typical of the Missouri River? Recently, scientists working on reproductive ecology of the white sturgeon have shown that free embryos hunker down in the interstices among rocks for a few days and develop fins and swimming muscles, before venturing into the drift.  Might this also be true for the pallid sturgeon?

To test this hypothesis, scientists at CERC are using outdoor artificial streams with two types of bottom substrate onto which the sticky, newly fertilized pallid eggs are ‘seeded’ (Figure 1).  In one stream, the small cobble substrate does not allow the pallids anywhere to hide after hatching so that they immediately drift upon hatching (Figure 2).  In a second stream, the eggs are adhered on and down inside a pile of larger rocks. Upon hatch, the embryos have more opportunity to maintain their position in among the boulders and emerge to drift after a few days of development.  Nets placed downstream of the rocks in both streams will catch the drifting free embryos.  If the pallids do delay their drift, then we would expect there to be a few days difference between the streams in the peak collection of free embryos in the nets.

 

Figure 1. Fertilized pallid sturgeon embryos are gently dispersed over the rock substrate. The PVC pipes are used to support a canopy of shade cloth to more closely mimic the muddy depths of the Missouri River.

Figure 2. Fertilized pallid sturgeon embryos are gently dispersed over the gravelrock 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 vulnerability of these tiny fragile larvae, and their urgent need to find a hospitable environment where they can feed and grow before their yolk is gone, strongly suggests this life stage could be a survival bottleneck for the population.    Although we will likely never be able to simulate in the laboratory the complex and extreme conditions in the Missouri River we must begin to think outside-the-box and creatively find ways to observe ecologically relevant pallid sturgeon early-life behavior.

By Diana Papoulias

Posted in Early life history |

Rain, Rain and More Rain

The 7-day precipitation forecast from the National Oceanic and Atmospheric Administration issued on May 27 showed local rainfall potential of approximately 5 inches for portions of north Missouri (figure 1).  Unfortunately, this forecast was relatively accurate and heavy rainfall swelled the Missouri River as the major storm moved through the mid-west.

Figure 1. The 7-day precipitation forecast from the National Oceanic and Atmospheric Administration issued on May 27.

Heavy rainfall during the last part of the week caused episodes of local flash-flooding and pushed the Missouri River over the National Weather Service floodstage of 23 feet at Jefferson City just before midnight on May 30, 2013.  Water levels finally crested at just over 30 feet on Sunday, June 2.  

 High flow presents several challenges and opportunities to researchers attempting to track pallid sturgeon in the Lower Missouri River.  First, we face the fundamental logistical challenge of finding boat ramps that are open, and if open, are not covered with mud and woody debris.  Flood waters can complicate the task of locating open boat ramps by causing road closures on low-lying roads, especially those in the floodplain approaching boat ramps (figure 2). 

Figure 2. Flood waters of the Missouri River and its tributaries cause road closures and prevent biologists from reaching boat ramps.

 Rising water can mobilize and carry large amounts of woody debris (figure 3), which severely complicates tracking, recapture and larval sampling efforts.  This woody debris isn’t just tree branches and limbs.  Entire large trees, roots and all, are frequently seen being swept downstream in the muddy current. 

 It can also be a challenge for crews to hear the telemetry transmitters of pallid sturgeon during flood flows because the debris and rushing water increases the noise in the telemetry signal, like static on a radio station.  Additionally, flood waters can increase habitat complexity by inundating sandbars and dikes, which can interrupt the transmitter signal (see previous blog entry “Sometimes It Takes Two”).  Although river conditions may occasionally prevent us from tracking these endangered sturgeon during high water, tags implanted inside fish will continue to record depth and temperature, and we will retrieve the data when the fish are recaptured later this year (see blog entry “Where Are You When I’m Not Looking”).

Figure 3. Large amount of woody debris are picked up and carried downstream by the rising waters of the Missouri River.

But the floodwaters also supply opportunities.  Some scientists have hypothesized that flood stages are instrumental in providing larval sturgeon access to near-shore and overbank areas.  High-water events present the opportunity to characterize habitats and drift in these areas.   In addition, high water helps habitat modeling studies that require sufficient depths that hydroacoustic boats can collect depth and velocity data over a broad range of habitats.

Posted in Flooding |

Pallid Sturgeon MIA

 When reproductive pallid sturgeon go missing during spring spawning season CSRP biologists become quickly concerned as every day at large means a decrease in the probability of relocation prior to spawning.  Because reproductive pallid sturgeon have been observed to move great distances (>10 miles per day), especially during spring spawning migrations, increased effort is required to search longer river segments when they go missing.  Pallid sturgeon may go undetected for a number of reasons but is typically one of the following three.  Pallid sturgeon may simply migrate outside of the estimated search radius, in which case subsequent searches covering more river miles may locate them.  Another possibility is that pallid sturgeon may move into habitats from which their acoustic signal does not resonate well or are not easily accessed by boat and therefore are not searched regularly.  In this case the pallid sturgeon might go undetected until it moves out of such habitats. Lastly, pallid sturgeon may migrate into relatively large tributaries that are not regularly searched.  Biologists believe that tributary confluences and the lower portions of tributaries may provide refuge, feeding opportunities, or reproductive requirements of the species in the highly modified Lower Missouri River.  This is exactly what biologists suspected when multiple days of searching the mainstem Missouri River failed to locate PLS11-004, a reproductive female previously found approximately 5 miles downstream of the Kansas River confluence in Kansas City, KS.  So up the Kansas River CSRP biologists went in search of PLS11-004, to river mile 15 to the Johnson County water intake weir.  Originally built in 1964, it has since seen its share of modifications and currently supplies roughly 10 billion gallons of water per year to Water District 1, or WaterOne, of Kansas.  CSRP biologists believed that if PLS11-004 had chosen the Kansas River, current river levels would not permit her to swim past the weir and she would certainly be in the lower 15 miles.  When it was all said and done PLS11-004 was located by another CSRP crew in the mainstem of the Missouri River approximately 15 miles upstream of the Kansas River, leaving biologist to wonder where she’d been and what she’d been up too.  In any case, her unpredictable behavior treated one CSRP crew to the sights and sounds of the Kansas River which they seldom frequent.

Johnson County water intake weir on the Kansas River.

 By Jake Faulkner

Posted in Telemetry tracking |

Across The River And Into The Trees

These weren’t just the last words of General Jackson in the Hemingway novel.  On Friday, April 12th, biologists located PLS11-004, a reproductive, female pallid sturgeon during her upstream migration, presumably to spawn.  In the morning PLS11-004 was observed crossing the river channel approximately one mile below the chute at Cranberry Bend (fig. 1).  This was exciting because she was heading upstream toward the chute, which is of particular interest to biologists.  The chute at Cranberry Bend, like many others along the Missouri River, is thought to enhance habitat diversity which may aid in the recovery of pallid sturgeon.  Pathways that fish take through chutes may also provide information to help in design fish-passage projects.  Documenting when and how pallid sturgeon use these habitats will help biologists to better understand the utility of such habitats to pallid sturgeon. 

 At approximately 2:40 that afternoon PLS11-004 reached the downstream entrance of the chute at Cranberry Bend, and found herself at a bit of a fork in the road, or in this case the river.  Both channels present different tradeoffs, but we can only speculate how PLS11-004 weighed the pros and cons at this intersection.  The next chirp of the hydrophone let biologists know she had forgone the mainstem and was on a path up through the chute.  With biologist hot on her trail, she spent the next three hours making her way through and around the numerous clumps of trees scattered throughout the chute (fig 2.).  In the end the trees did not appear to be used as a resting place, as Jackson envisioned, but none the less afforded something more suitable for PLS11-004 as she continued her migration upstream.  A few days later, USGS hydrologists mapped the velocities in the chute and mainstem in an attempt to quantify why she selected this path.

Figure 1. Point locations, and 24 hour time, showing the movement path of PLS11-004 as she negotiated the Missouri River from river mile 279 to 282 nearly Waverly, MO.

 

Figure 2. Although female pallid sturgeon PLS11-004 seemed to navigate the cluttered chute with ease, biologist, on the other hand, had to give careful consideration to their every move in their large river vessel. 

 

Posted in chute, Telemetry tracking |

The Gang of Eight

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.

Figure 1. Recent locations (as of May 6, 2013) for the eight reproductive pallid sturgeon being tracked by researchers.

Posted in Reproductive Female, Telemetry tracking |

The Other Sturgeon Species

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 are and 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 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 nose snout. It is commonly referred to as a “rubbernose” sturgeon.

 

Posted in Uncategorized |

Rising To The Challenge

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

Posted in Telemetry tracking |

Sometimes The Missouri River Is A Lonely Place

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

Posted in Reproductive Female |

Ice Ice Baby

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.

 

 

Posted in Telemetry tracking |