I Spy our First Sturgeon

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.

Stationary receivers mounted in concrete anchors ready to be deployed.
Stationary receivers mounted in concrete anchors ready to be deployed.

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.

The white dots are our first detection of pings by from a tagged Lake Sturgeon by one of our stationary receivers!
The white dots are our first detection of pings by from a tagged Lake Sturgeon by one of our stationary receivers!