Popular media coverage of Lake Sturgeon characterizes them as an ancient fish, and few adjectives could be more apropos. Yes, they are ancient on geological time spans. The fossil record confirms there have been sturgeon like fish swimming somewhere on the planet for 250 million years. However, the characterization as “ancient” works on multiple levels. In terms of an individual’s life history, sturgeon can live to be ancient. By counting rings on fin spines or ear bones scientists have determined that Sturgeon can live to over 150 years old (Pflieger 1997). A final connection I will offer to sturgeon being old is a little more metaphoric and —“gasp”— anthropomorphic. We are beginning to learn that our tagged Lake Sturgeon, like your parents or grandparents that go to dinner at Denny’s every Tuesday evening at 4:30pm and order nothing but the 55+ grilled cheese and soup, (cut diagonally!!), are often creatures of habit. When it comes to where they go and when, Sturgeon can be downright curmudgeonly, obdurate, and immutable.
Case in point, there are fish like Aldo and Cosmopolis that wander about the lower Missouri Basin and then reliably show up in the Gasconade in the spring. There is Moe, which last summer was the lonely soul who braved the soupy bathwater of the lower Gasconade River by himself, returning this summer to its steamy waters. There is Edward, who is the only fish that really seems to like a particular shallow, wood-strewn reach in the lower Osage. He showed up right on time in the early summer just as he did last year. Julio, Liam, the list goes on. Fancy statistical analysis of site fidelity and homing in our Lake Sturgeon will come once we have collected a couple more years of movement data, but the anecdotal evidence is racking up that some sturgeon may be predictable. When you are guessing, correctly, which tag is about to ping as you round the river bend it probably is not a leap to imagine something more than random is occurring. A recent paper showed similar behavior in Lake Sturgeon in the St. Clair system that connects Lakes Huron and Erie. The population of Sturgeon broke out into four movement patterns that were more or less consistent across years (Kessel et al. 2018).
Just like long-lived people, perhaps long-lived fish when making decisions — such as where are good places to find food, where are good places to rest — defer to experience. However, when our environment is changes faster than the population is turning over, what is a sturgeon to do? When the price of the 55+ grilled cheese and soup special raises 30 cents to adjust for inflation you had better believe we are going to hear some grumbling. This is a big ecological question and one that takes decades to address, but it is one worth thinking about. For the sake of our long-lived species and the long-term health of aquatic ecosystems, there is no time like the present to begin.
Kessel, S., D. Hondorp, C. Holbrook, J. Boase, J. Chiotti, M. Thoomas, T. Wills, E. Rosman, R. Drouin, and C. Krueger. 2018. Divergent migration within Lake Sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor. Journal of Animal Ecology 87:259-273.
Pflieger, W. L. 1997. The fishes of Missouri, 2nd edition. Missouri Department of Conservation, Jefferson City, Missouri.
Swimmers, take your mark… Lake Sturgeon in the Osage and Gasconade Rivers are on the starting blocks waiting to embark on their spring upstream migrations. A few fish in the Gasconade, may have already jumped the gun. On February 27th, a warm rain had the Gasconade out of its banks, and that was just enough to convince a few over eager sturgeon it was time to move. Three fish moved began moving upstream as the water rose and traveled at least 9 miles from near the confluence with the Missouri River past Fredericksburg. Even in the Osage River Lake Sturgeon were stacking up in the heads of pools just upstream of their winter haunts seemingly antsy to get underway. Except the problem was that a few days later air temperatures and flows began to plummet with water temperatures dipping back under 50 degrees Fahrenheit. The fish responded by, pausing in the lower river. In many populations the first to arrive on the spawning grounds are the males. The females tend to hang back and arrive a few days later. The optimal spawning temperatures are from 52-60 F.
During the cold spell, we switched to setting gill nets to capture and tag a few more staging Lake Sturgeon in the Gasconade. By the end of the week we had tagged 8 Lake Sturgeon bringing our total to 27 in the Gasconade and 93 overall. On the last day, we captured one of the plumpest Lakers we had ever seen. During surgery, developing eggs began bursting through the incision; eggs that that hopefully will be deposited on a rocky shoal sometime later this spring. Females only spawn ever 4-7 years. The year before the spawn the eggs will be yellow turning from gray to black by the next spring. The eggs told the story. She was almost ready. The eggs had a dark bullseye, the germinal vesicle which during development moves to the pole of the egg. Farmers who raise sturgeon for caviar production have often looked at the germinal vesicle to judge egg stage. It would still take a little time before they were ripe. Following fish like this throughout the spring migration will give us an idea where, if at all, the Lake Sturgeon are attempting to spawn. We are expecting some rain next week, and a slow warming could this be the time?
Like the sturgeon, myself and most of my friends and coworkers are ready for spring as well. Going fishing when most of the ponds are too chilly to get a bite, starting to think about checking our favorite spot for morels. Our female sturgeon was a reminder to be patient. Spring will be here soon, and before we know it giving way to the oppressive heat of Missouri summer.
Bruch, R. M., and F. P. Binkowski. 2002. Spawning behavior of Lake Sturgeon (Acipenser fulvescens). Journal of Applied Ichthyology 18:570-579.
My last post was a desperate plea to my tagged sturgeon. “Come and see me, I miss you!” I lamented, and guess what, the guilt trip worked! Last week we spent three days gill netting Lake Sturgeon on the Gasconade River and captured 8 individuals. Six were new, but two were fish we had tagged last fall. Our first recaptures!
All jokes aside, as with every field trip, we learned something new. For instance, the fact that our first and only recaptures occurred on the Gasconade River provides more evidence that the Gasconade River is home to fewer Lake Sturgeon than the Osage River. The much smaller Gasconade may simply lack the space to support as many Lake Sturgeon as the Osage, or there may be other habitat factors that make the Osage River more desirable for sturgeon. Now that we have tagged almost 20 Lake Sturgeon in the Gasconade, we have a sufficient sample size to start comparing their movement and habitat selection to the 56 Lake Sturgeon that we tagged in the Osage. This comparison can help us learn how Lake Sturgeon respond to flow manipulations in the regulated Osage River by using the free flowing Gasconade River as a control.
This also provided a good opportunity to check and see how our fish were recovering from surgery. The first recaptured fish was the only fish we had captured on a trotline in the Gasconade River this past fall. The second fish was also tagged last fall but was captured both times using a gill net. The incision sites on both fish seemed to be healing well with no external signs of infection present.
If this blog is really a mysterious communication channel to Missouri River Lake Sturgeon, I’ll put it in writing that all of you should spawn this spring. And make sure you are as conspicuous as possible about it too. Lots of splashing on the rocks please.
With rows of sharp scutes lining their body, Lake Sturgeon are a little rough around the edges, literally, but I can’t help but love them anyway. I also am afraid I am beginning to develop a common pathology of among scientists where constant thought your study species, leads to concern about their well being. In the final stage of this condition, the scientist adopts a protectionist role. Let’s call it Mother Hen Syndrome. Each time I release a tagged sturgeon, I feel like the over anxious mother sending their child off on the bus on the first day of kindergarten. Will they be okay? Will the other sturgeon ostracize them for their stitches on their abdomen?
Complicating matters is the fact that, my tagged sturgeon have been giving me the cold shoulder. My running total of tagged Lake Sturgeon is 79 individuals in the Osage and Gasconade rivers. Over the more the 5,000 setline hook nights it took to capture these 79 sturgeon how many recaptures have I had? If you guessed zero, you would be correct. Again I think of the mom who sends their kids off to college, “you never call!!”
To a population ecologist, there are a couple explanations for low recaptures of marked organisms. First, there is a “trap effect” where the capture process causes an organism to avoid sampling gear in the future and therefore is less likely to be recaptured. And secondly, you have only managed to tag a small proportion of the population and thus are more likely to capture unmarked individuals than marked ones. I don’t have an answer to explain the lack of recaptures I’ve seen and haven’t found conclusive evidence in the literature as well. I did come across a 2004 report from the Michigan Department of Natural Resources that reports below expectation recapture rates for fish captured in trawls, suggesting a behavioral avoidance of trawls. Although they didn’t notice as striking of a pattern for setline recaptures, it is certainly possible that a Lake Sturgeon might avoid the offering of a juicy earthworm after having been poked by a 8/0 hook once. Using side-scan sonar, the report’s authors estimated that between 5,000 and 29,000 sturgeon use 1 square mile of habitat in the St. Clair River Delta. In our time on the river we have noticed lots of large bottom dwelling fish on sidescan sonar returns in areas where tagged lake sturgeon are hanging out. With the abundance of large fish species present in the Missouri River basin including Blue and Flathead Catfish or Paddlefish, it can be hard to know if large fish on sonar are definitely Sturgeon. I was reminded of the difficulty in estimating population size as I read the famous quote a colleague had pasted in his email signature “Managing fish is like managing trees, except they are invisible and they move.” The exact same applies to counting them.
Population estimates are beyond the scope of my project which is focused on habitat use and movement of Lake Sturgeon. Some day perhaps another graduate student will devise an ingenious study to answer these very questions in order to better assess the status of Lake Sturgeon in the Missouri River basin. And to all of the biologists out there, please share if you know of any studies addressing this or have anecdotal observations from your own sampling for Lake Sturgeon.
To end on a positive note, all signs point to the fact that my Sturgeon are thriving. They are behaving like a sturgeon should moving, hanging out in predictable habitats. A few weeks ago I even received an email from a biologist who had been contacted by an angler who had accidentally caught one of my tagged sturgeon while Sauger fishing. Updates like these are always soothing, nonetheless, their avoidance still gnaws at me a little bit. I miss my babies. Why the cold shoulder?
Thomas, M. V., and R. C. Haas. 2004. Abundance, Age Structure, and Spatial Distribution of Lake Sturgeon Acipenser fulvescens in the St. Clair System. State of Michigan Department of Natural Resources Report No. 2076.
Reminders of Missouri’s connections to agriculture are everywhere. Drive the I-70 corridor across the heart of Missouri and the dominant vista corn and cows punctuated by an occasional billboard. To and from our field sites on the Osage River, the views are much the same. Here denuded hilltops, are grazed low by roving herds of black Angus. Yet I still somehow expect fisheries fieldwork to be an escape from the land of livestock. Sure there are the occasional small pasture creeks we work in, used by cows as personal watering trough, swimming pool, and toilet. More often though field sites are set in rugged river hills and creek draws that have been allowed to grow up in bristling stands of oak and hickory. So you can imagine my surprise when sampling for Lake Sturgeon this year, up from the watery depths we pulled a spotted cow and a hulking hog. These weren’t literal cows and hogs but rather curious specimens of one of Missouri’s largest fish, the Blue Catfish (Ictalurus furcatus).
Let’s start with the cow. The bovine Blue Cat pictured below was produced by a genetic mutation (or mootation if you appreciate a good pun). They call this color morph piebald. At first, I probably was not appropriately appreciative of this catch. In addition to his years studying fish, my coworker Brandon, a self described river rat who grew up along the banks of the Missouri river running trotlines for catfish, was amazed. I don’t need a geneticist to tell me about incidence rates of this abnormality, when Brandon says it was the first he’d ever seen, I’ll believe him that it was special.
But that wasn’t our last encounter with curious catfish in 2017. Just this past month, a hog appeared in our nets. Struggling to catch Lake Sturgeon to tag for our research in the Gasconade River on trotlines, we decided to try different gear in the nearby Missouri River. We deployed large mesh gill nets in fishy looking spots and then returned the next morning to see what we had caught. As we began pulling in our first gill net it became clear we had caught something huge. Vince and Brandon pulled on lead line with all of their might, but it wouldn’t budge. Rather than snaring a monster Lake Sturgeon, it became clear that a giant sunken Cottonwood washed off an eroding bank had become ensnared in our net. This inauspicious start was compounded by the embarrassment of Vince’s presence who happens to be one of the chief biologists in our state agency’s research division. I was hoping the second net would produce a Lake Sturgeon to make Vince’s trip worth his while and to make us look a little more competent and worthy of his agencies research funding.
We motored down the wide muddy channel to a backwater opening behind an rock channel dike. The chilly autumn air spurred me to switch places with Brandon at the front of the boat, who having struggled pulling on the cottonwood, had sweated through his 5 layers of fleece clothing. As Vince and I began pulling in the net we found some fish. We plopped a few 10-15 lb Blue and Flathead catfish into the holding tank as we drew in the monofilament panels. About halfway through, I began feeling another weight. I was beginning to lament that we’d caught another Cottonwood, when the weight began to shake subtly as a fish thrashed around. We slowly raised the wiggling weight until it finally broke surface. “Oh my!” we collectively exclaimed, our voices elevated excitedly to pitches seldom reached by full grown men. Boat-side was the gaping maw of the largest catfish either of us had ever seen.
At first we had no idea how to even bring this fish into the boat. I quickly realized that my decision to stick my fingers in its mouth were ill advised. Its bite force was like a vice grip and its tooth patches a combination of the sticky side of a velcro strip and sand paper, quickly chafing layers of skin. We did a three-count and together, hauled the leviathan over the gunwale. In gill nets fish usually get their head stock in one of the square mesh panels, but the catfish was mainly stuck due to its pectoral spines. Dulled with age, this is one feature of catfish that is more fearsome when they are small. This fish had long outgrown the need for razor sharped barbed spines to defend itself from predators. Its proportions simply didn’t make sense. The flesh ceased to be fish-like. I imagined trying to clean such a fish, the thick meaty slabs would look more like pork loins than fillets. Like many catfish if you listened closely enough you could hear the fish grunting just like it had hooves and curly tail. When it came time for photos before the fish was released, I thought back to my trip to the gym earlier that week. How much had I curled? Not anywhere close to 92 lbs. Somehow, I conjured enough strength to hold the fish for a momentary photo before clumsily dropping it back in the tank on the boat.
Underlying this story of the giant catfish, is the Missouri River’s rapidly recovering population of big blues. The Missouri has become known as a trophy fishery that has produced multiple record catfish in recent years and regularly hosts big catfishing tournaments. Large Catfish used to be rare sight for anglers and biologists in the Missouri River. Many factors were responsible for the decline including habitat alteration and overharvest. Large sunken trees which provided fish cover, were removed to aid in steamboat travel (Hesse 1987). Additionally, dikes and training structures built to tame river channel for flood control and barge travel had eliminated important shallow habitats that supported Blue Catfish and their prey. Although many of the habitat issues remain unresolved, in 1992 several Midwestern states, including Missouri instituted a ban on the commercial harvest of Blue Catfish. This allowed catfish more time in the feedlots to fatten up for anglers. At smaller sizes, Blue Cats bulk up on whatever they can fit in their mouths. Sometimes even resorting to filling their guts with clams and vegetation. In Virginia, I once held a Blue Catfish that rattled like a maraca when shaken due to all of the the clam shells jangling inside its stomach. As they mature catfish develop a penchant for fish. Gizzard shad, Silver carp, Goldeye, Mooneye, whatever is abundant and easy to catch. Left alone to gorge, catfish can live to be 20 years or more in Missouri but not all old fish reach such large sizes. The 92 lber was an exceptional grower, and although we can’t give a precise age is probably over 15 years old (Graham 1999).
It is to early to pin all of these successes on the regulation change. The Missouri Department of Conservation and multiple graduate students at Mizzou are conducting Blue Catfish research to better understand the population dynamics. However anecdotal evidence from angler observations and a recent state record fish weighing 130lbs, a whopping 40 lbs more than our catch, was caught in the Missouri River in 2011, show that big fish still swim in the Show-Me-State. For more information on Missouri’s monster fish see the following two articles recently published in local media:
Last Tuesday our research crew (Brandon, Bailey, and I) made a trip down to MDC’s Lost Valley Hatchery. Our goal was to assist with the fall stocking effort of Lake Sturgeon in Missouri. When we walked through the open garage doors into the main production room we found ourselves on the floor of a veritable fish assembly line. Biologists worked at stations each completing a simple task with efficiency that would have made Henry Ford proud. The purpose of this assembly line wasn’t to build cars or electronics to stock in showrooms and on store shelves, but to tag baby Lake Sturgeon to stock in the Osage and Gasconade rivers.
On the cuteness scale baby Lake Sturgeon rank somewhere between the Puppy Bowl and a tiny sloth taking a nap. Their long spade-shaped snouts turned ever so slightly upward at the tip. Their camo colored exterior specifically evolved to help them blend into the rocky bottoms of the streams they are born in to. Their five rows of sharp scutes discourage most hungry bass and catfish from trying to gobble them up. And there were 12 runways chock full of the things.
Like the migratory adults these fingerlings were already quite the travelers and you couldn’t blame them for being a little homesick. They started out as eggs obtained from adults in the Yellow River way up in Wisconsin. They were shipped down to Missouri where hatchery staff provided them with plenty of tender loving care to ease the transitions feeding them bloodworms, maintaining clean water and preventing disease.
The main job of the volunteer crews was to make sure Lake Sturgeon received two tags. At the first workstation biologists reached down into the water grab a sturgeon. Then using a scalpel they would scrape off the 9th spine or scute on the fish’s right side. The process was quick and relatively painless for the fish. Think of it like getting your nails trimmed. The marked fish was tossed into another tank to await transport to station #2.
At workstation #2, each Lake Sturgeon received a coded wire tag. When one worker had the needle in position another pushed a button on a machine to inject a 2 mm surgical steel tag into the fish’s back. This little piece of wire can be detected with a metal detecting wand, like the ones security folks use sometimes at airports. The positioning of this wire, more specifically what scute it is located under, will tell biologists what year it was stocked if they should encounter it in the future. This information can be used to estimate growth and survival in the population. The Sturgeon are tagged twice in case one of the marks is marks is obscured over time (sturgeon can lose other scutes or the coded wire tag may fall out).
At the end of the day, while a hungry crew gorged on grilled burgers and hotdogs, hatchery staff scooped up the Sturgeon in nets and hoisted them into the tank on a hatchery truck. A couple hours later they would be shot out of a hose and be swimming free.
The outpouring of volunteers who showed up to see off the 5,000-6,000 fingerling Lake Sturgeon epitomizes how Lake Sturgeon recovery is a team effort. My work on movement and habitat selection by Lake Sturgeon being just one tiny component. Led and organized by our “foreman”, MDC Lake Sturgeon recovery biologist Travis Moore, we can continue to make progress in bringing this species back from the brink of extinction in the state. Even if it is just reporting and releasing Lake Sturgeon you catch, or practicing good land use practices that keep our water clean, like on the assembly line, each of us can have a small, but crucial, role to play.
The natural history of the Osage River is epitomized by one concept: movement. The battle for the soul of the river has been based on whether it should be a thoroughfare of navigation, a vast pool for recreation, or a corridor for migration. Navigation and recreation, those are human uses, and to attain them you need engineers and tons of rock, concrete, and steel placed strategically to tame the river. Migration, on the other hand, is for the fishes. It was the default state of the river before Anglo-Americans displaced the Osage Indians and settled the river valley. Looking back at the early history of the Osage River and its management we can better understand the current state of the ecosystem and how one mode of movement won out.
When it comes to fish passage in rivers, dams can either be walls or hurdles. Walls, keep things out and are completely impassible in the upstream direction. These are the high-wall dams that are built for hydropower or flood control. The ones that impound large reservoirs lined with houses, docks, and businesses. Hurdles, are impediments but are not necessarily impassible to fish. It may take a little more effort or time waiting for the right conditions, but strong swimming fish can get past them. The Osage is, at least from a Sturgeon or Paddlefish’s perspective, is cursed with both.
Building Hurdles for Navigation
Everyone from Merriwether Lewis to the Osage Indians had realized that the Osage was a poor river for commercial navigation. The blithe optimism of engineers and their philosophy of “river improvement,” meant that reshaping the Osage into a conduit for barge travel from Bonnots Mill to the Kansas Border was worth a try. The first, and save for numerous rock dikes and training structures scattered around the river, the last major attempt at accomplishing this was Lock and Dam #1. Lock and Dam#1 was is currently located just upstream of the confluence of the Osage and Maries rivers around 12.1 miles upstream of the Missouri River. NO. 1 was built in 1895 to create slack-water navigation channels in the Osage River by raising the water level upstream to allow barges to ascend an estimated 98 rocky riffles in the river. The Army Corps of Engineers quoted a cost of $187,244 but by the time all was said and done, the cost had ballooned to $417,500. Common trade items mentioned in the report were things like nails, salt, lumber and pork. A great share of this was lumber which is often easier to simply float down an unobstructed, swift-flowing river. Plans for a series of locks and dams to make the river more navigable were discontinued by the 1920’sIn 1951 L&D 1, no longer useful for much of anything was sold along with the surrounding land and buildings for a meager $10,000.
Building Walls for Recreation
In the 1920’s investors began thinking about the construction of large reservoirs that would put an end to the dream of an Osage navigable by people and fish. By 1904 congress had officially classified the river above Warsaw as unnavigable, paving the way for hydroelectric development. In 1931, Union Electric built Bagnell Dam and Lake of the Ozarks. The privately owned dam which is maintained today by Amren UE generates hydroelectric power. Bagnell Dam inundated 84 square miles of river valley including the whole town of Linn Creek, MO. In 1979, a second dam was constructed by the Army Corps of Engineers for flood control further upstream to create Truman Lake.
After a slow start, Lake of the Ozarks has become a tourist and vacation hotspot in the Midwest. The Osage left behind a legacy of steamboat travel and towering bluffs over churning waters and embracing a future of luxury yachts, waterskiing, and Netflix dramas starring Jason Bateman. Recreation has firmly supplanted, navigation, and migration as king of the Osage.
Implications for Lake Sturgeon
Lock and Dam #1 is a hurdle for many fish species including Lake Sturgeon and Paddlefish on seasonal migrations. Neither species can bypass Bagnell or Truman Dam. Non-self sustaining populations of Paddlefish are stocked throughout the watershed including in Lake of the Ozarks and Truman Reservoir. Lake Sturgeon were believed to have been extirpated from the Osage upstream of Bagnell until a resident captured a photo of a Lake Sturgeon swimming near their dock in Lake of the Ozarks in 2017. Whether this fish was introduced by anglers or is a part of a remnant population that survived after impoundment is not known.
A big theme of my research is to determine what effect the hurdles and walls have on Lake Sturgeon and their recovery in Missouri. Through tracking their movements over the next 4 years we will have a better idea of how they behave in response to unnatural flow patterns and barriers. For instance, we have designed our tracking schedules and stationary receiver deployment locations to be able to identify roughly the time at which a Lake Sturgeon passes Lock and Dam #1. We can relate that to water levels which may allow us to make flow recommendations to improve passage success during key times of the year such as during spring migrations.
No one really knows how far Lake Sturgeon historically swam upstream the Osage in their quest to spawn. Their close relative, the Paddlefish which pre-impoundment had one of its largest populations in the world in the Osage River, required gravelly shoals upstream of the Truman Dam. This has left the Paddlefish utterly dependent on artificial stocking to sustain populations. Our fingers are crossed that Lake Sturgeon are less picky and will still be able to spawn on one of the many shallow rocky areas that still exist downstream of Bagnell Dam.
Recently things have been pretty quiet around the Lock and Dam. We have had few passages since late spring. However, during a fairly low flow level an intrepid young sturgeon named Sidney made the leap downstream over the dam. I say leap, because that was exactly what it must have been. The fish would have encountered a fairly large drop whether it passed through the lock chamber or over the dam itself. What cued Sidney in this downstream movement? We don’t know? Opportunities to pass back up will be rare during the typically lower flows of fall and winter. If we presume the sturgeon knows this and is ditching the upper river for the time being, perhaps it is significant.
You have to wonder if like a phantom limb, today’s sturgeon can still sense the tinglings of the severed upstream habitats. Will Lake Sturgeon congregate below these barriers on their spring migrations, or will they improvise and find new places to spawn. Perhaps today’s adult Lake Sturgeon population, most of which were Wisconsin Lake Winnebago strain fish, have no memory of those historic spawning grounds and make do with what they have in the lower river. The hurdles and walls in the Osage aren’t going anywhere anytime soon and hopefully t these barriers to movement won’t prove to be major barriers to conservation success.
Much of the historical information in this article was gathered from Leland & Crystal Payton’s outstanding and beautifully published book on Osage River History titled: Damming the Osage, the conflicted story of Lake of the Ozarks and Truman Reservoir.
Human personality traits are often presented as dichotomies. You can get online, take a short test, and within minutes know if you are an extrovert or an introvert, a thinker or a feeler, a judger or a perceiver, and the list goes on. After about two months of tracking we are learning that Lake Sturgeon can be divided into two major categories: the movers and the stayers.
Some sturgeon just can’t seem to sit still for long. Adventurous sturgeon like Richard, Joe, Sigurd. Sigurd, named after one of my favorite nature writers and explorer of Canadian glacial lakes Sigurd Olson, was tagged back in 2015 by the Missouri Department of Conservation. Sigurd moved further upstream than any of our Sturgeon and came within a few miles of bumping his snout into Bagnell Dam in June. Over the past two months, Sigurd has moved at least 81.8 miles. And since it was tagged the total is at least twice that distance. Richard and Joe were Sturgeon we tagged this year. They quickly recovered from the tag implantation procedure and made significant upstream and downstream runs totaling at least 103 and 82 miles respectively. What is driving the restlessness in these fish remains unknown, but it may be related to characteristics of the individuals — our most mobile Sturgeon have been 20-30 lb males— and environmental conditions — sustained high flow releases from Bagnell Dam to combat upstream flooding gave way to lower summertime flows by mid June and as a result our big movers have transitioned back downstream to a few key pools.
We tagged plenty of homebodies too. Fish like Joe, Richard, and the ironically named Miles have found good homes and are content to stay there. These fish have remained within a 0.5 mile stretch of river since tracking began. We might worry that they were dead if it were not for subtle upstream movements between tracking periods.
The seasons also likely have an impact on Lake Sturgeon movement patterns. Most fish seem to be moving less as water temperatures rise to potentially stressful levels. Other papers have been published suggesting that water temperatures over 28 C are stressful for Lake Sturgeon. Our research may be able to highlight temperature or flow characteristics that Lake Sturgeon select for during these stressful periods. Perhaps by knowing a little bit about an individual Lake Sturgeon and the environmental conditions we will be able to predict its answer the proverbial question that separates the movers from the stayers: Should I stay or should I go?
The wind ripped out of the south ushering in record warm temperatures. Thermometers were creeping into the 70’s in mid February. The maples had been duped by faux arrival of spring, their branches teemed with red buds along the banks. Under the translucent brownish turquoise water, things were much calmer. The Osage although very low was still pumping 2000 cubic feet of water per second downstream. When this mass of water met the mighty Missouri River less than a mile downstream, it backed up like too many sports fans funneled through the turnstiles at a stadium. This turned the river into a placid backwater. Despite this apparent quiet under the surface, things were beginning getting noisy, we just couldn’t tell yet.
Earlier that morning we set out four of our stationary acoustic receivers and a telemetry tag in a straight line each separated by 100 m. The tag sends out sound signals or “pings” every 12 seconds. The receivers are essentially underwater microphones that record the pings.The goal of this mini experiment was to determine over what distance the stationary receivers were able to detect pings from the tag. If the furthest receiver, 400 m away, could detect most of the pings then theoretically it should be able to catch the pings from any tagged sturgeon that swims up the 300 m wide Osage River when we deploy the receivers for for real. Brandon and I were stretched out on the boat, trying our best to kill time, letting the technology do the work for us. We had four hours to kill while we waited for the receivers to listen for pings.
When the clock finally struck 3:30 we hastily retrieved our gear. Brandon guided the blue F-250 up the winding roads along the loess river hills. I began downloading the data to our field tablet. Luckily, all four receivers seemed to be picking up at least 80% of the tag transmissions which means that the likelihood of a receiver missing at tagged Sturgeon swimming by should be relatively low.
And as proof of our theory, we happened to detect our first tagged Lake Sturgeon by accident! Fish number 26025 is a Lake Sturgeon that was tagged by Missouri Department of Conservation Biologist Travis Moore last Spring. This fish was a big boy too, measuring 48 inches long and weight 32 pounds. Could it be starting its migration up the Osage in search of spawning habitat? Only time will tell. The battery in this fish’s tag should last another couple of years allowing us to collect information on where it moves and what habitat it prefers.
I’ve finally emerged from a long blogging hiatus. This emergence coincides with an emergence from my troglodytic existence in the basement of ABNR Building on Mizzou’s campus. Troglodytic or cave dwelling, is not an exaggeration of how I have spent the winter. Unaccustomed to the brightness of the outside world, my first day in the field left me with a cherry-red face and moderate eye strain.
Soon the first warm days of the season will also rouse the Lake Sturgeon in Missouri’s rivers out of their winter sluggishness. As they begin to move they will likely be rather hungry as well. Hungry enough, we hope, to readily gobble a gob of nightcrawlers on our trotlines. After which we can surgically implant acoustic telemetry tags to track their movements over the next 4 years. But all of this work is for later posts. There are many preparatory activities that need to be made for the field season.
The goals of the first forays into the field were to assess the potential study area which includes the larger tributaries to the Missouri River that we expect Lake Sturgeon to swim up during the spring in search of spawning habitat. My main focus is on the Osage and the Gasconade, but Lake Sturgeon are unpredictable, the Chariton, Grand, Lamine, and Moreau rivers might entice a wayward Sturgeon as well. This leaves me and my trusty side-kick Brandon with 100’s of miles to patrol for the fish we tag, which unless we can find a house boat that can navigate these rivers, is an unrealistic goal.
However, there is another way around this. We can deploy “eyes” or rather “ears” to patrol these rivers for tagged Sturgeon 24-7. These ears are Vemco stationary receivers. These receivers have microphones built in that can detect the sound “pings” emitted by the tags implanted in our Lake Sturgeon. For example, we may tag a sturgeon in the Osage River. If this fish decides to swim up the Grand River within say 500 m of a stationary receiver, the receiver will log the fish’s tag number for us to download later.
The biggest issue with the stationary receivers is choosing the best place to set them to 1. prevent damage or loss during floods and 2. to prevent loss via theft (not sure why anyone would want one of these). One secure place researchers have used in the past are bridge piers, with permission from the Department of Transportation of Course. The river channel is the highway for migrating sturgeon and swimming upstream means they must pass under these bridges where we can observe their presence with stationary receivers during times we aren’t able to manually track them.
A good bridge pier for a stationary receiver is one that is in deep water, and has low flow velocity. Swift flow can create extra noise that interferes with the receiver’s microphone.
In addition to looking at bridges which isn’t terribly exciting, I also got a first look at some of my study sites. Some were more scenic than others. And some cool wildlife along the way.