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?
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.