{"id":13489,"date":"2026-04-02T09:02:27","date_gmt":"2026-04-02T14:02:27","guid":{"rendered":"https:\/\/www.wisconsin.edu\/all-in-wisconsin\/?post_type=campus_story&p=13489"},"modified":"2026-04-02T09:02:27","modified_gmt":"2026-04-02T14:02:27","slug":"frozen-findings-uwl-biology-graduate-studies-fish-winter-behavior-to-inform-habitat-decisions","status":"publish","type":"campus_story","link":"https:\/\/www.wisconsin.edu\/all-in-wisconsin\/story\/frozen-findings-uwl-biology-graduate-studies-fish-winter-behavior-to-inform-habitat-decisions\/","title":{"rendered":"Frozen findings: UWL biology graduate studies fish winter behavior to inform habitat decisions"},"content":{"rendered":"\n
\"Screenshot:<\/a>
UWL Alumnus Ben Patschull, ’20 & ’25, a water resource management specialist with the Wisconsin DNR, captured videos of different fish species moving around in their winter habitat in the backwaters of the Mississippi River. In this video, a bowfin swims into view. Video courtesy of Patschull.<\/em><\/figcaption><\/figure>\n\n\n\n

On a frigid February day, Alumnus Ben Patschull steps across the frozen backwaters of the Mississippi River, his ice cleats scraping against a sheet of ice that forms a roof over a hidden world below. <\/p>\n\n\n\n

Beneath the surface, more than 140 species of fish inhabit the Upper Mississippi River. For Patschull, the river isn\u2019t just their home. <\/p>\n\n\n\n

“I grew up in La Crosse and fishing all of these spots, so that was a big inspiration for me to do this work,\u201d he says, lifting his auger out of a freshly drilled hole in the ice.  <\/p>\n\n\n\n

Patschull earned both his bachelor\u2019s and master\u2019s degrees in biology <\/a>from UWL. Now a water resources management specialist with the Wisconsin Department of Natural Resources (DNR), he studies fish habitat in the Upper Mississippi River \u2014 with a particular focus on what happens during winter, one of the least understood seasons in freshwater ecology. <\/p>\n\n\n\n

A winter refuge<\/h3>\n\n\n\n

Research conducted in the 1990s showed that species such as bluegill and largemouth bass often seek out slow-moving backwaters in winter. These areas typically remain slightly warmer \u2014 often just above 2 degrees Celsius \u2014 compared to the faster-flowing main channel, which can hover near 0 degrees. <\/p>\n\n\n\n

\u201cColder water in the main channel, combined with flow, can stress or even damage fish,\u201d Patschull explains. \u201cThe backwater is warmer and maintains adequate dissolved oxygen levels. We call it a thermal refuge \u2014 pockets where fish can survive over the winter.\u201d <\/p>\n\n\n\n

That makes backwater habitat critical for some species. But the Upper Mississippi River is home to more than 140 fish species, and for most of them, scientists don\u2019t know what habitats they use in winter \u2014 or how they respond to changing water conditions. <\/p>\n\n\n\n

Building a better way to see<\/h3>\n\n\n\n

To fill that gap, Patschull developed an innovative under-ice camera system \u2014 one he largely built himself. <\/p>\n\n\n\n

His setup includes a welded metal frame that stabilizes a 360-degree underwater camera beneath the ice. The camera connects to recording equipment adapted from consumer electronics, allowing him to monitor fish activity in real time from above the ice. A small screen rests near the hole, occasionally lighting up as a fish glides past. <\/p>\n\n\n\n

The goal is to document which species use backwater habitats in winter, estimate fish density and measure water quality variables such as dissolved oxygen and filamentous algae levels. In high concentrations, certain algae can alter oxygen availability and create lethal conditions for sensitive species. <\/p>\n\n\n\n

On this February day, Patschull is alone on the ice. <\/p>\n\n\n\n

\u201cI think that has a lot to do with people not wanting to go outside in the cold,\u201d he says with a smile. <\/p>\n\n\n\n

But winter, he argues, is exactly when scientists need to be there. <\/p>\n\n\n\n

From graduate research to management tool<\/h3>\n\n\n\n
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