Fish Fry Day Redux: Video of Smallmouth Bass Begging for Samples

While you’d be right in accusing us of “mailing it in” in this week’s version of the “Fishes of Wisconsin” challenge, we’ll make it up to you by presenting not one, but two cool underwater videos of smallmouth bass doing their thing!

Smallmouth bass. Photo: Marilyn Larsen
Smallmouth bass. Photo: Marilyn Larsen

First up, some smallies in an undisclosed lake in northern Wisconsin keep trying to steal former CFL grad student, Gretchen Hansen‘s, research right out of her hand. This video is several years old, but Hansen was surveying rusty crayfish populations in several Vilas County lakes and, well, let’s just say a lot of the rusties never made it to the collecting bags!

Then we head south to Lake Mendota and listen as our former undergrad intern, Emily Hilts, narrates a snorkeling adventure as she caught several smallmouth bass preparing nests for the spawning season. Also note the, um, different hue in our more southern lake’s “clear water phase!”

Until next week, enjoy Fish Fry Day, when Wisconsin restaurants and the CFL blog put fish on the menu!

Field Samples: How Fish Find Their Niche

Field Samples is a Q&A with aquatic researchers. Today the incomparable John Magnuson talks about research on how fish find their niche. John will give a public lecture today at noon in the Water Science & Engineering Lab as part of the Center for Limnology’s weekly Wednesday seminar

Who are you, where are you from, and how did you get here?    

John Magnuson. Photo courtesy: Clean Lakes Alliance
John Magnuson. Photo courtesy: Clean Lakes Alliance

I am John J. Magnuson, born in Illinois, schooled in Illinois, Minnesota, and the University of British Columbia, Canada. I came to UW-Madison as a faculty member in Zoology with an office in the Limnology Laboratory. My position before coming to Wisconsin was as a blue water fishery oceanographer in the Central Pacific stationed on Oahu.

Pretend we just boarded an elevator and you only have one-minute to tell us about what it is you’re presenting on at seminar.  

What determines where fishes are distributed? Their physiology and behavior allows them to choose places to be in a lake or stream based on water temperature, dissolved oxygen, food abundance, and other features. I will focus on what we call their “niche” in a complex of environmental features. Across Wisconsin and the world fishes move through a systems of lakes and streams that resembles what we can think of as islands isolated or somewhat isolated from other waters. Invasions and local extinctions occur in these islands that determine which fishes form the community of waters across the landscape.

Why should someone not in the field of freshwater sciences care about your work?

I was drawn to these question by curiosity and my life experiences. Being a sea-going ocean scientist in the Pacific conditioned me to later look at lakes as “islands” here in Wisconsin. The information is useful to fishery scientists, conservation biologists and agencies making decisions about fishes and conservation.

What question did you answer or do you hope to answer? What other questions might your work lead scientists to ask?  

How do fish locate a place to live in a complex environment? This includes human modifications to that environment, such as a heated effluent from a power generation facility or dams along a once connected river. Second, in what ways are fish communities in lakes and streams determined by the same process that determine the land dwelling species that live on oceanic islands? As our world climate warms and changes, how will the new environmental features of lakes and drainage systems influence fishes?

What do you love about your work? What do you love not-so-much?      

I am an emeritus professor and have the chance to do science for the same reasons I entered the field of fish and fisheries ecology. I enjoy learning,  discovery, problem solving, being out in nature, working with students and helping students and the public learn about the world around them.  

Tell me about one funny, memorable, exciting or awesome moment from your work either in the field or in the lab.

For me this is a challenge because I have been doing science for some 60 years. Picking one memorable moment is practically not possible! But to comply here is a short story:

After studying the thermal niche of fishes in the laboratory (in other words, what temperatures they preferred to hang out in), we began to ask whether the laboratory results [were reflected in] their distributions in the field. We started locally with Lake Monona and the thermal outfall from MG&E (the warm water returned to the lake via a power plant in downtown Madison). We then looked a Lake Michigan and how fishes were distributed on the bottom as the thermocline’s boundary swept back and forth at mid-depths. We then were attracted to the north wall of the Gulf Stream on the continental shelf off of Cape Hatteras in the Atlantic. The meanders of the stream, like a flag in the wind, swept north and south along the shelf [changing the water temperature wherever it meandered]. At each step to larger more complex and open waters, I was excited that we could predict the thermal niche of fishes based on what we’d learned from lab experiments. Fishes in the thermal plume in Lake Monona, the dynamic thermocline in Lake Michigan and, finally, the meanders of the north wall of the Gulf Stream in the Atlantic were all trying to stay in their ideal thermal niches.

Where do you hope to go from here either with this work, or, literally, after your time at Hasler Lab?

I hope to stay active at the Center as long as I can make contributions and not become a burden!

Continue reading “Field Samples: How Fish Find Their Niche”

Art Hasler, Bluntnose Minnows and How Salmon Get Back Home

Happy Fish Fry Day! It’s the day that, like restaurants across Wisconsin, we put fish on our menu. Today’s main course – bluntnose minnows.

Bluntnose minnow on "Fishes of Wisconsin" poster. Photo: Marilyn Larsen
Bluntnose minnow on “Fishes of Wisconsin” poster. Photo: Marilyn Larsen

As we tackle the “Fishes of Wisconsin” challenge, striving to write a post for each of the 183 species of fish found in Wisconsin, one might expect to stumble across a species that, well, just isn’t all that interesting.

I’m happy to report that the bluntnose minnow is NOT that species. In fact, it’s the second species of minnow in as many weeks with connections to an iconic historical figure in our field of study.

Bluntnose minnow.
Bluntnose minnow.

Sure we could tell you that ol’ Pimephales notatus is very likely the most common freshwater fish in the eastern half of North America. We could divulge what it eats and what eats it. Or discuss the new look it gets during the breeding season. But the important thing here is to know that, like many fish, the bluntnose minnow follows its nose.

And that nose played a pivotal role in Art Hasler’s discovery of how salmon return to their natal streams to spawn.

Flash back to the spring of 1945. World War II is over and Art Hasler, a well-established limnologist from the University of Wisconsin-Madison, is serving his country, cataloging the damage done to research stations and laboratories and other scientific edifices as a member of the U.S. Air Force’s Strategic Bombing Survey. Continue reading “Art Hasler, Bluntnose Minnows and How Salmon Get Back Home”

Celebrating World Wetlands Day 3 Ways

Tomorrow is World Wetlands Day, a celebration of the importance (and warning of the fragility) of some of Earth’s most beautiful ecosystems.

The tidal marshes of the Blackwater National Wildlife Refuge, Maryland. Photo: A. Hinterthuer
The tidal marshes of the Blackwater National Wildlife Refuge, Maryland. Photo: A. Hinterthuer

Wetlands, the transitional ecosystem from an aquatic environment to terra firma, provide an incredible array of services to their surrounding landscapes – they filter sediment and pollutants out of the water, they absorb overflow and prevent floods, they provide critical habitat for crabs, fish, waterfowl and a host of other wildlife.

Yet, since the settlement of the United States, we’ve lost more than 50% of our wetlands – draining land for agriculture, paving it for cities, or putting it underwater with dams. With that loss, we’ve seen declines in fisheries and water quality and a rise in flooding and erosion.

Today we’re offering three stories on wetlands to celebrate World Wetlands Day on Februrary 2nd. (Okay, two stories and one slideshow!). We hope you don’t mind getting your feet a little wet!  Continue reading “Celebrating World Wetlands Day 3 Ways”

Winter Redux: What Do Fish Do Under the Ice?

This weekend saw temperatures in the 20s, the sun shining and scores of anglers sitting over holes in the ice of Madison lakes. So we thought we’d revisit a post from this time last year – what life is like for the fish in winter.
These guys can't wait for ice-off so they can start sneakin' Photo: Fargo-Moorhead Dive News
These guys can’t wait for ice-off. Photo: Fargo-Moorhead Dive News

[Originally posted Jan. 30, 2015] – While we’ve been spared (so far) by any sort of climate shenanigans like a polar vortex this winter, our lakes have had a nice thick cover of ice on for a month or more. And lots of people ask variations of the question – what’s life like for fishes under the ice?

Well, the short answer is “Not much different than the rest of the year.” They eat and breathe and try to avoid becoming lunch.But there are some interesting elements to winter life, so we asked CFL grad student, Alex Latzka to help explain. (NOTE: Alex is now a post doctoral research at McGill University)

Up on land, while everything from bears to bats to turtles to raccoons is all curled up, cozy and hibernating, fishes have no such luxury. They have to keep moving enough to pass water over their gills and continue to breathe. But, still, Latzka says, everything slows way down.

“Most forage fishes (like bluegill, or other species that serve as prey for bigger fish) have to stay really still and not expend a lot of energy,” Latzka says. “So they are hanging out in structure, or weed beds, where there’s cover and some food.”

Alex Latzka holds up an impressive pike pulled form the ice of an “undisclosed” Madison lake. Dan Oele assists.

Predators, like northern pike, are then hanging out near the weed beds waiting for something to venture out. Still, Latzka says, “They’re not eating a lot.” Cool water fish like pike and bluegill lose weight in winter, since they can’t find enough food to make up for the “metabolic cost,” or calories they’re burning just staying alive.

In fact, according to the book, “Ecology of Teleost Fishes,” by Robert J. Wootton, in some instances, fish like bluegill won’t eat all winter long, relying on fat stores they accumulated in the fall to get by.

Burbot. Image: New York DNR
Burbot. Image: New York DNR

On the opposite end of that spectrum, cold-water species of fishes thrive in these conditions. While a pike looks a little worse for wear in spring, species like burbot come out of the experience fat and happy. We don’t have burbot in Lake Mendota, but we once had lake trout and cisco, other cold water species that loved long winters, since they weren’t confined to their summer hangout in the coldest, deepest parts of the lake.

And that brings us to another winter issue for fish under the ice – oxygen. With the “lid” on the lake, precious little oxygen enters the water column and  fish are left to survive on what got mixed into the lake in the fall. That’s one reason they slow down so much – being all active and burning through their oxygen reserve is a bad idea.

Oxygen is particularly limited at the bottom of the lake, where microbes are decomposing all of the organic matter that settled out during more productive months. Thanks to the overabundance of nutrients driving all of that growth (and algal blooms) during the summer and fall, Lake Mendota has a LOT of organic matter resting on the bottom and those microbes use up a ton of oxygen breaking it down. The end result can be either hypoxic “low-oxygen” or anoxic “no-oxygen” conditions at the bottom of the lake.

These so-called “dead zones” can also form in summer and are a big reason why you don’t see lake trout or cisco in Lake Mendota anymore – those fishes couldn’t survive when the only remaining parts of the lake with cold-water habitat kept running out of  oxygen every summer.

This is as much excitement as this pike (and Alex Latzka and Jereme Gaeta) will have all winter! Photo: A. Hinterthuer

One final thing about life under the ice that Latzka finds fascinating, is that, in winter, a lake’s habitats get a lot less diverse. “In warmer months, the temperature can vary all over the lake,” he says. Water is nice and warm at the surface, still quite cold down deep, and all sorts of temperature in between those two extremes.

Every species can spread out in search of their optimal temperature comfort zone.

But in winter the entire lake is, more or less, the same temperature. Usually 3 or 4 degrees Celsius. And that leads to behavior you won’t see quite so dramatically in summer.

“If you find warm water inlets,” Latzka says, “and let me qualify by saying ‘Be careful walking on ice near warm water inlets!’ But, where you have pulses of warm water, a lot of species of fish are going to want to be in it, because those levels of temperature change, just a couple of degrees, effects how active they’re going to be, how much they can eat and they’ll grow better in those conditions.”

So there you have it – the not-quite-exciting story of life under ice for our fishes. They mostly stay still, hang out in the same spot and, like a lot of us, wait for spring and open water to get back in action.

Fishes of Wisconsin: Louis Agassiz & the Mississippi Silvery Minnow

Last year we launched an overly ambitious project here on the blog – post each week about one of the 183 species on the epic “FIshes of Wisconsin” poster. That proved easier said than done, but we’re back and ready to tackle more of the 13-foot-long behemoth.

Panorama is a must for a poster this epic. Kandis Elliot's "Fishes of Wisconsin" poster.
Panorama is a must for a poster this epic. Kandis Elliot’s “Fishes of Wisconsin” poster.

This week, a few interesting tidbits about the Mississippi silvery minnow (Hybognathus nuchalis). 

Photo: Marilyn Larsen
Photo: Marilyn Larsen

The Mississippi silvery minnow, like most (but not all) minnows is a small, silver-colored fish found in large schools. This particular minnow prefers the slack water habitat or pools and backwaters  along medium to large rivers and streams. It’s range stretches all along its namesake river from Wisconsin to the Mississippi delta, although it doesn’t stray too far east or west of the Mississippi (except for a population in Texas). Continue reading “Fishes of Wisconsin: Louis Agassiz & the Mississippi Silvery Minnow”

Video: Limnology 101 – Lake Stratification

CFL graduate student, Colin Smith, produced and narrated this first video in our new “Limnology 101” series. Here he explains why lakes separate into warm, upper layers and cold, bottom layers.  Check it out!

Stay tuned for more “Limnology 101,” as we explain some of the basic physical and biological principles of the study of our inland waters.

Note: The video is of the “demonstration only” variety. Some content may not be 100% scientifically accurate, but is still a good example of the basic principles of density and stratification. 

The Bold Prediction on Lake Michigan’s Sport Fishery That, Unfortunately, Was Proven Right

by Steve Carpenter

Every moment, our brains make predictions of what we will next encounter in our lives based on our lifetime of experiences. As our experiences are updated, our brain adjusts and accounts for the new information in its next predictions. The discovery that brains engage in co-evolving cycles of predictions and actions is one of the great accomplishments of neuroscience.

Jim Kitchell's land-mark paper on the Lake Michigan and Lake Huron fisheries accurately predicted tough times for salmon and lake trout. Photo: Detroit Free Press
Jim Kitchell’s land-mark paper on the Lake Michigan and Lake Huron fisheries accurately predicted tough times for salmon and lake trout. Photo: Detroit Free Press

In a microcosm, it represents the way science is made. Scientists routinely make predictions to evaluate ideas. Usually those predictions are wrong and, through these mistakes, we make the ideas better.

Occasionally, however, a scientist is confident enough to make a public prediction and hits the nail on the head. Center for Limnology director emeritus, Jim Kitchell and his colleagues, Don Stewart and Larry Crowder, made such a prediction in 1981, and now their paper is honored as a Fisheries Classic by the American Fisheries Society. Continue reading “The Bold Prediction on Lake Michigan’s Sport Fishery That, Unfortunately, Was Proven Right”

Science on Tap Adds New Short-Format Series to Its Video Archives

IMG_1998On the first frigid Wednesday night of February, 2013, Science on Tap-Minocqua held  its first event at the Minocqua Brewing Company in northern Wisconsin. On February 3rd, we’ll mark the 3-year anniversary with a talk by Trina McMahon on the “Microbes All Around Us.”

We’re celebrating the anniversary with a new series of short-format “highlight” videos. If you can’t make it to Minocqua or tune in online, and if you don’t have time to watch a full-length recap, we’ve got you covered! Our new 5 to 10 minute videos will highlight the primary points of each talk. It’s not the same as being there, but it is a great way to get up-to-speed on a whole lot of amazing science going on in Wisconsin!

You can find the videos on the Trout Lake Station YouTube channel. Our first is a recap of Jonathan Patz’s talk from last October. Patz, who shared the Nobel Prize as a co-author of the IPCC reports and is currently director of the Global Health Initiative at the University of Wisconsin-Madison, spoke about how the world’s response to climate change may prove to be the biggest public health “win” of this generation (video below). Stay tuned for  Stan Temple’s talk on why using cutting-edge science to resurrect extinct species may not be a great idea and Patricia McConnell on the science of dog behavior!


Awards, Judges Set for “Our Waters, Our Future” Writing Contest

MADISON — Two of Wisconsin’s literary leaders will help decide the winner of the Our Waters, Our Future writing contest. Peter Annin, journalist and author of Great Lakes Water Wars, and Fabu, as Madison’s third poet laureate is professionally known, have agreed to help select the top stories that imagine a positive future for water and people in south-central Wisconsin.

What is your vision for the future of Madison's lakes? Image:
What is your vision for the future of Madison’s lakes? Image:

The contest encourages Wisconsinites to envision a desirable future and participate in building that future through storytelling. Representatives from Madison Magazine, which will publish the winning story, will also be part of the judges’ panel.

Peter Annin. Photo: Northland College
Peter Annin. Photo: Northland College

“We are leaving the century of oil and entering the century of water, which means water will become the most important natural resource in the world by 2100. Communication—especially writing—can play a key role in helping people understand just how important water is becoming on a regional, national and international level,” says Annin, who is also the co-director of the Mary Griggs Burke Center for Freshwater Innovation at Northland College.

Originally from the southern United States, Fabu draws on her connection with the Mississippi River, which she says has “watered [her] both historically and creatively.”


“I felt at home in Wisconsin when I saw the Mississippi River in La Crosse. It has been a pleasant discovery learning about the various waters in Wisconsin. Our Waters, Our Future speaks to the importance of this resource, and I am excited to read what writers say about this topic,” says Fabu, who served as Madison’s poet laureate from 2008 to 2012.

Several local businesses specializing in outdoor recreation have offered their support of the contest as awards sponsors for the winner and top finalists, including Fontana Sports Specialists, Brittingham & Wingra Boats, Rutabaga Sports and REI. Local artist John Miller, whose work often features water, will also create an illustration for the winning story.

The contest seeks short stories that are solutions-oriented and, while fictional, are also scientifically plausible. Stories should take place in the year 2070 and in the region around the Yahara Watershed and/or the affiliated counties of Dane, Rock and Columbia.

Despite this regional focus, the contest is open to all Wisconsin residents and students 18 years or older. Since the region contains the state’s capital and flagship university, thousands of acres of productive farmland and valuable water resources, including the Yahara river and lakes, the issues it faces have statewide significance.

The deadline to submit stories is February 1, 2016. Complete contest details can be found at

The contest is a collaborative effort by the University of Wisconsin-Madison’s Water Sustainability and Climate project and Center for Limnology, Madison Magazine, Sustain Dane and the Wisconsin Academy and Sciences, Arts & Letters.


CONTACTS: Peter Annin,, 715-682-1360; Fabu,, 608-235-4745; Jenny Seifert,, 608-512-6259