Coldwater Fish Science in the Heart of the Driftless - 2025 Edition

This blog has given me a chance to share a bit about my "day job" and the activities of our Trout Unlimited chapter, the Coulee Region Chapter of Trout Unlimited. The annual coldwater fish science meeting our chapter co-hosts on the UW - La Crosse campus is maybe my favorite evening of the year and the marriage of the job that pays me and the one that does not - that of chapter president.

The evening is an opportunity for our students to showcase their efforts and share their research findings with a friendly audience. That audience is always bolstered by the power of extra credit. We turn out 50 or more students from Organismal Biology and Ecology courses that are there for extra points. But I get to read some of their write-ups and they really do enjoy the evenings and they get a chance to see what their fellow students are doing.

The crowd - always our largest of the year - is 18 to 80 years old. For over an hour, we learned about research the students and Wisconsin DNR fisheries biologists have been conducting.

WDNR Fisheries Biologists

The evening started with a talk by WDNR fisheries biologists in the La Crosse office. We have a great relationship with our local biologists and have two great biologists. Kirk Olson is the Senior Fisheries Biologist and Tommy Hill is a fisheries biologist in the La Crosse office. They presented their summer work which was a bit about trend sites - streams that are sampled each year - and their work in the Coon Creek watershed - this summer's targeted watershed.

Kirk Olson (left) and Tommy Hill (right) present their summer sampling data.

Tommy started out the evening by talking about they "whys and hows" behind the WDNR sampling. How trend sites are sampled each year - there are a at least three stream reaches per stream at 35 times the mean stream width in length or at least 150 meters. These trend sites are used assess changes to streams over time and to better understand year-to-year variability in trout populations and size structure across the region. The most recent report on these sites is from 2025. And he talked about their rotational watersheds approach, where they will sample every major watershed in their four county area about every seven years. This allows for a more in-depth analysis of conditions in each watershed and a chance to compare conditions at seven year intervals. Recent survey reports out of La Crosse are:

• West Fork Kickapoo

• Bear Creek (Upper Kickapoo River)

• Lower La Crosse River and Halfway Creek

• Southern Crawford County

• 2025 Wadable Streams Trout Population Report for La Crosse, Monroe, Crawford and Vernon Counties

• 2024 Wadable Streams Trout Population Report for La Crosse, Monroe, Crawford and Vernon Counties

• 2021-2023 Wadable Streams Trout Populations Report for La Crosse, Monroe, Crawford, and Vernon Counties

WDNR's Ryan Olson (left) and Tommy Hill (center - with backpack), demonstrating electrofishing during our summer River Navigation and Sampling Techniques summer course.

Kirk went on to talk about the data and wove in some interesting pieces of history. The Coon Creek watershed is one of the "troutiest" in the state and has an interesting history. Some of the first watershed-based work in the country occurred near Coon Valley in the Coon Creek watershed. I have written a number of posts about how Driftless Area trout streams are in MUCH better condition than they had been historically (visit the linked posts at the bottom of this post for more). Today, the streams of the upper Coon Creek watershed are home to some of the highest trout densities in the state and probably the world. Of particularly interest was a look at trout populations and size structure over time. Wild, self-sustaining trout are more common than they were historically (1950 to maybe the early 1990's) but down a bit from historic highs in the late-1990's to early 2000's. In most streams, these are stream-bred non-native Brown Trout, that may have followed a population trajectory similar to many invasive species where populations reach a maximum and then slowly level off to a more moderate density. Look for more information about the Coon Creek Watershed study when it is published. We will share it - as we always do - on the Coulee Region TU Facebook page.

Above are images of summer sampling with the Wisconsin DNR La Crosse fisheries crew.

Water Temperatures in the Coon Creek Watershed

Two undergraduate students, Audrey Sorensen and Emma Walkowiak, presented data from temperature loggers they placed in the Coon Creek watershed. These data will be an important part of the upcoming comprehensive watershed study. We cooperated with Kirk and Tommy, our local fisheries biologists, along with those in the WDNR Watershed program on the project. We placed about two dozen temperature loggers in the spring and retrieved (most of them) after the trout season had concluded.

Audrey (left) and Emma (right) presented data from temperature loggers that they placed in the watershed to support the WDNR comprehensive watershed for the Coon Creek Watershed.

Emma and Audrey presented last year as well - and about five or so other times, including at the Driftless Science Symposium, over the past year. They have become professionals at giving these talks. Last year, we put out temperature loggers across a larger geographic area; this year, they were concentrated in the Coon Creek Watershed. These loggers belonged to Coulee Region TU, the WDNR, and our research lab at the University of Wisconsin - La Crosse.

The slideshow above allows you to see a few of their slides. The map was created by the WDNR will be part of their comprehensive watershed report that will be published before the next field season. The other figures are of the variation in water temperatures - which we have found that low variability tends to show a stronger influence of groundwater - and a figure that they also created in R that shows the maximum monthly temperature of each stream reach.

Air temperature data from the Viroqua airport for the summer of 2025.

One interesting finding was that all but a couple of streams reached their summer maximum temperature on June 22nd. Last year's data showed much more variation in when each stream's summer maximum temperatures occurred. Looking at air temperatures above, it is quite obvious that the overnight temperatures in the mid- to high-70's did not allow streams to cool off overnight as they typically do.

Pammel Creek / ORA Trails Community Trail Farm Brook Trout Populations

Our lab group has "adopted" Pammel Creek on the Outdoor Recreation Alliance (ORA) Trail Community Trail Farm property along State Road / Highway 33 on the East side of La Crosse. This 250+ acre property will be transformed into a recreational and educational facility over the next number of years. There are plans in place to remove some of the sediment deposited along the stream banks and remove non-native riparian plants like buckthorn and honeysuckle. Being so close to the UW - La Crosse campus, many classes, students, and faculty have teamed up with ORA Trails to study this property and assist with its ecological restoration. Josh Hein, the project administrator, has been a wonderful partner in our lab's efforts and he will be the guest speaker at the Coulee Region TU banquet in February.

Sam Anderson (left) and Madison Wall (right) presented the lab group's research on Pammel Creek, a small Brook Trout stream on the outskirts of La Crosse.

We have been sampling Brook Trout redds (nests) these past two falls and we are starting to accumulate a dataset on the populations of Brook Trout and their lengths and weights. These data will serve as the "before" data to assess how restoration of the stream changes Brook Trout population parameters. Below are images from our lab's spring electrofishing training and sampling.

Sam Anderson, a sophomore at UW-L, and Madison Wall, a soon-to-be graduate of UW-L, presented the lab's data from Pammel Creek. About two dozen students - both undergraduate and graduate students - have been part of this research the last couple of years.

Brook Trout populations are above Driftless Area median values - meaning they are more common in Pammel Creek than they are "in your average Driftless stream". The average density has been around 2,000 fish per mile. And redd surveys are ongoing with the peak number of redds occurring in mid- to late-November (trout spawn later than many anglers tend to believe...).

This image is of our data analysis meeting before the presentation. Students and faculty are using RStudio to analyze the data and create figures for their presentation.

One finding of particular interest is that Brook Trout were nearly an inch longer in the fall of this year than they were in the fall of 2024. Was it due to a mild winter, a summer more conducive to growth, the improvements to a machinery crossing, or some other factor(s)? We don't know but we intend to continue to study the stream and have plans to snorkel it this spring to look for Brook Trout emerging from those redds. These emergence dates and densities, along with data from four temperature loggers that are in the stream, should provide us with more information about this wild, self-sustaining Brook Trout population.

Effects of Geology on Brook and Brown Trout Production and Biomass

The fourth talk of the evening was Kyle Kamm's presentation about research he is planning on conducting this spring and summer. Kyle is a first year Master's student that is advised by myself and Dr. David Schumann. His research is a collaborative project with the Wisconsin DNR - Kirk Olson is a committee member - and is an extension of a previous graduate student's research (Brandon Thill's thesis) that started our journey looking at how geology affects water temperatures, habitat, and trout population characteristics.

Kyle Kamm, a first year Master's student, presentation of his research plan for this spring and summer.

Kyle is in his first semester at UW-L and comes to us from UW - Stevens Point. Master's student's first semester are about getting to know their subject - so A LOT of reading - and planning for their research. Kyle has come up with a plan for this summer and shared it at the event in his first graduate school presentation. He has a lot to make sense of - understanding geology and how it affects water temperatures, quantity, and quality; fish sampling and how to estimate production and biomass, differences in the biology of Brook Trout and Brown Trout, and a number of other components to his research. Planning is paramount to a successful research project and Kyle is well on his way to a good and interesting project.

Those that regularly read my ramblings in this blog may recognize the topic of P:B ratios from a past blog post. Kyle's research will be our lab's first application of P:B ratios. He has worked with Kirk Olson of the WDNR to select study sites based on combinations of geology and trout assemblage type. One of the difficult parts of the planning process is always around the question of what is feasible? What Kyle has worked out is that he will sample three reaches in three different streams in each combination of geology and trout type (below).

• Sandstone geology & Brook Trout dominant

• Dolostone geology & Brook Trout dominant

• Dolostone geology & Brown Trout dominant

• Mixed geology & sympatric Brook and Brown Trout assemblages (though after his committee meeting this week, we may forego this to reduce the number of sites he needs to sample.)

One of Kyle's slides - images I took from when Brandon and I were out in the field during his study - show the differences in physical habitat in dolostone and sandstone geologies.

Those doing the math at home have already figured out that means 36 (3*3*4) sample reaches. These 36 reaches should encompass the variability within each of geology and assemblage types. And, almost as importantly, while it is an ambitious sampling regime, it is (hopefully) feasible in a relatively short amount of time - which will make the estimates of production and biomass comparable among samples.

Distribution of Mottled and Slimy Sculpin in the Kickapoo River Watershed

Changing the topic from trout to my favorite fish - sculpin; Evan Sirianni was the last speaker of the evening. Evan comes to us from UW - River Falls and the Hayward office of the WDNR. He is a second year Master's student at La Crosse. His project had him collecting fish and habitat data from 60 streams in the Kickapoo River watershed. His project has been funded by a grant from the TU - Driftless Area Restoration Effort and the National Fish Habitat Partnership.

Evan Sirianni is finishing up his Master's degree at UWL and did a great job presenting his research findings.

While Kyle is in the planning stages, Evan is working on wrapping up his research and is well into writing his thesis. Mottled Sculpin and Slimy Sculpin are both native to the Driftless Area. They are closely related species and telling them apart is for experts - like Evan (see below for a slide on how to tell them apart). Like most non-game fishes, we know less about them than we would like but finding funding for non-game species is always difficult. Below are some images from the Native Fish Coalition / UWL spring event to kick off Evan's research.

Evan's objectives were to better understand the distribution of these two native fishes and relate their presence or absence on environmental variables. He found sculpin to be present in a little less than 50% of the sites he sampled. Mottled Sculpin were in more streams, Slimy Sculpin were uncommon and thus more difficult to determine they "whys" behind where they were, or were not. Both species were present together in only one stream reach. A number of environmental variables such as dissolved oxygen, aquatic vegetation, current velocity, stream temperature,and others were related to the presence and absence of sculpin. I'll wait until Evan is done with his thesis before sharing too much of it and allow him to do that himself.

One of the most challenging parts of Evan's research is that much of what we see today is likely an artifact poor agricultural practices that occurred many decades ago. Sculpin are sensitive to sedimentation and to tie back to the first talk of the day, our area has a history of sedimentation unlike most anywhere in the world. I have to think that sculpin were once much more common and widely distributed in the Driftless Area. The WDNR is reintroducing them to part of their range and Evan's work should help select sites where they are most likely to be successfully restored.

The Wrap-up

As I said when I was closing out the evening, I'm a little biased but it is always one of my favorite evenings of the year. It is a great opportunity for students to share their research and for students to get to see what resource professionals with the WDNR do as part of their jobs. I'm always happy for the number of people - CRTU chapter members and students - that come and listen. And for the Wisconsin DNR La Crosse fisheries crew for their support for these projects and Kirk's willingness to serve as a committee member for our graduate students.

For those in the Madison area, I look forward to presenting some version of this at the April 14th Southern Wisconsin Chapter of Trout Unlimited meeting. And, as I had shared yesterday, this is the last blog post on this website. Thank you for reading one last time and keep and eye on the Coulee Region TU website for an update about some of these blogs seeing the light of day again. Who knows what the future will hold - both for these blog posts and these students.