Path of least resistance?

The black circles and red dashed line indicate the upstream migration pathway of reproductive female, Code 56, in the Yellowstone River on June 4, 2011. The inset image is a cross-section of the river’s depth and velocity in the side channel across the specified telemetry location (black line). The fastest water is indicated by red, and the slowest water is indicated by the purple end of the spectrum.

USGS hydrologists and biologists joined with biologists from Montana Fish, Wildlife, and Parks to radio track pallid sturgeon as they navigated the Yellowstone River during late May and Early June.  Following one fish over the course of a day with telemetry allowed them to map the fish’s pathway as it migrated upstream (see previous post about tracking in the Yellowstone River).   Using an acoustic Doppler current profiler (ADCP) to measure the depth and velocity of the river at recorded telemetry locations, they obtained detailed information about the habitats and energetic requirements of the pallid sturgeon’s migration.

The black circles and red dashed line indicate the upstream migration pathway of reproductive male, Code 19, in the Yellowstone River on June 8, 2011. The inset image is a cross-section of the river’s depth and velocity across the specified telemetry location (black line). The fastest water is indicated by red, and the slowest water is indicated by the purple end of the spectrum.

This year pallid sturgeon in the Yellowstone River have had more options during migration -the high water this spring is providing access to side channels and overtopped sandbars unavailable in most years.  The female, Code 56, swam from one side channel, directly across the main channel and straight into another side channel.  The male, Code 19, crossed the channel four times and went through one very small side channel.  Why did they select side channels in their pathway?  And does the pathway have a relation to the morphology of the river?  These are questions we hope to be able to address because of the hydrologic conditions this year.

Completed with contributions by Brandon McElroy