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.
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.
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:
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.