We haven’t posted to the blog much recently because USGS and Nebraska Game and Parks (NGPC) crews have been busy, strung out from Missouri to South Dakota trying to keep tabs on wayward sturgeon.
Downstream in the state of Missouri we have been tracking one reproductive male who took off on a 45-mile sprint last week. He stopped for a couple of days at an L-dike (an L-shaped pile of rocks used to control the flow of the river), in Miami, Missouri. A spawning site? We’re not sure, and unfortunately male behaviors are unpredictable. Meanwhile, two reproductive females have been listless until this week when water temperatures approached 17°C (63°F); now they are heading upstream, but not at the same rate, and not together.
Upstream near Plattsmouth, Nebraska, four reproductive females have gone missing (temporarily, for sure), possibly headed up the Platte River. The Platte is wide, shallow, and full of shifting sandbars that make fish tracking especially difficult, but we’ve sent a shallow-draft boat up the Platte to see if they appear.
Further upstream, our colleagues with NGPC have tracked a reproductive female that traveled 60 miles upstream from Ponca, Nebraska through very cold water in the mainstem Missouri River nearly to Yankton, South Dakota. Just shy of Yankton she hesitated, milled around a bit, and then took a hard right turn up the James River, (known locally as the “Jim”) which is almost at flood stage and 4-6o C warmer than the Missouri. After making a 4 mile dash up the Jim and hanging out for at least 12 hours, she returned to the Missouri River, completeing her Jim River trip in a weekend. Her migration pattern was suggestive and the temperature was nearly optimal at 18°C (64°F). Did she spawn? USGS and NGPC crews are presently trying to recapture her, sampling for pallid sturgeon larvae drifting down the Jim, and assessing habitat at the apex of her journey. More on this fish next week.
And even further north, USGS and Montana Fish, Wildlife, and Parks crews are just beginning to locate potential fish to track this season in the lower Yellowstone and upper Missouri Rivers. This important collaboration will provide critical information on pallid sturgeon reproduction in river systems with very different hydrology and channel form compared to the Lower Missouri.
These fish lead us every which way. Notwithstanding our frustration with their antics, we know that there is useful information encoded in their behaviors – where they spawn, when they spawn, and under what hydrologic conditions. Every time they do something unexpected, we gain useful information for breaking that code.
– By Robb Jacobson