Tracking Northern Pike in Green Bay

Posted on May 7, 2012 by admin

CFL grad student, Dan Oele, is trying to see if pike return to their “birthplace” to spawn or if any ol’ tributary will do. Watch (or read) below for a peak into his research.

GREEN BAY — It’s the second day of April and Dan Oele is cruising the tributaries of Green Bay on the hunt for northern pike.

“I always come down here to see if I can see any fish staging to come up but it doesn’t really look like it.”

Dan Oele checks a hoop net for pike

This would normally be a good time to spot adult pike as they head inland from Lake Michigan for the shallow wetlands, streams and even road culverts where they spawn. But, this year, Oele’s not spotting many pike in the tea-colored water. For many of the fish, the spawning run is already done.

“It’s a pretty wild spring.,” Oele says. “The warm temperatures really bumped up all the fish migrations, the spring migrants. From walleye, sturgeon, suckers, northern pike are at least four weeks ahead of schedule and its all water temperature related. That really hot spell in mid-March started things really early.”

Oele is a graduate student in Pete McIntyre’s lab at the Center for Limnology at the University of Wisconsin-Madison. He’s working on a masters’ degree thesis exploring the nature of pike migrations.

“The core question,” he says, “is ‘Are northern pike returning to the same areas they were born in to spawn every year?’ That is, do they show natal site fidelity? And the way we’re answering that question is through otolith microchemistry.”

Joseph Brooks displays two otoliths taken from a northern pike

Otoliths, tiny disks of calcium carbonate often called “ear stones,” sit near a fish’s brain and help it detect sounds and vibrations, as well as orient itself in its 3-D underwater world. For researchers, otoliths are indispensible recorders of a fish’s life history. Not only do they have growth rings, much like trees, but they take in trace elements of the surrounding habitat as they grow. Since the water chemistry of an inland stream is different from a Great Lake, these changes show up in all fish, including the pike Oele studies.

“So a young fish is born in a tributary, stays there for a little while, migrates back out to Green Bay or Lake Michigan to grow up and mature. And when it’s mature enough to spawn going back into a tributary, we can detect those subtle changes in the otolith chemistry.”

Oele and Brooks record data on a pike taken from one of their nets

In several tributaries around Green Bay, Oele has set up hoop nets that allow pike to swim upstream to spawn and then corral them as they head back downstream. On this particular day, only one net turns up a pike. Oele and his field assistant, Joe Brooks, remove the pike from the net and take a series of size and weight measurements as well as scale samples and fin clippings. They then remove the otoliths.
Oele needs to catch ten fish in each of his nets to have enough evidence to take back to the lab. Once there, he can analyze the chemical make-up of each otolith to try to reveal if pike should join the ranks of fish like salmonids and suckers that return to their birthplace to spawn or, if pike simply head inland in the spring and use any suitable habitat to lay their eggs.

“Apart from being a really cool science experiment,” Oele says, “this has some really strong management implications. And that is, if pike are going back to the same areas to spawn, if you’re going to create a new wetland or habitat for pike to spawn, you’re going to have to seed it somehow with young fish that will imprint on that water body and in that way they’ll find it. And, if the opposite is true, and these fish are just cruising the coast of Green Bay and waiting for the water temperatures to get warm and clue in on that, you can reasonably expect to build a pristine wetland habitat and just leave it be and the fish will find it on their own.”

The answer to his question, Oele says, might one day help fisheries managers better protect future populations of one of Wisconsin’s biggest, and most popular, sport fish.

Oele displays the lone catch of the day. The unseasonably warm March weather drove an extremely early spawning season this year

 

Posted in Ecological Processes, Fish, Fishing, Boating & Water Recreation, Graduate Student Research, Hasler Lab, Uncategorized | Tagged , , , , , , , , , , , | Leave a comment

CFL’s Susan Knight Wins UW “Excellence Award”

Posted on April 30, 2012 by admin

Susan Knight (ctr), accepts her award from Chancellor Ward (rt) and Carroll Heideman (lt)

Last Thursday, UW Chancellor David Ward hosted a reception for the winners of the 2012 Academic Staff Excellence Awards. Susan Knight, Trout Lake Station’s interim director and outreach specialist, was one of the eight award winners invited. Susan won the Robert and Carroll Heideman Award for Excellence in Public Service and Outreach and the CFL couldn’t be prouder of her.

Susan Knight shows visitors to Trout Lake Station's 2011 Open House how to ID milfoil

CFL director, Steve Carpenter, calls Susan the “friendly and highly informative face,” of both the CFL and UW-Madison in northern Wisconsin. Susan works hard to both keep Trout Lake Station humming along, as well as educate residents and schoolkids about limnology. Her passion is aquatic plants and, via formal workshops, school programs, or at CFL open houses, she’s making sure fans of Wisconsin’s freshwater ecosystems know their aquatic macrophytes one demonstration at a time. When she’s not fulfilling the Wisconsin Idea and engaging residents in learning about their freshwater surroundings, Susan is busy working on her research in northern Wisconsin lakes.

Congrats, Susan, on a well-deserved award!

Posted in Awards & Milestones, CFL In The News, Trout Lake Station | Tagged , , , , | Leave a comment

Smallmouth Bass: One Hazard of Fieldwork in Wisconsin Lakes

Posted on April 25, 2012 by admin

Center for Limnology grad student, Gretchen Hansen, took this video from a past summer’s field season up in Vilas County. While we’ll honor the tradition of fishermen not sharing their favorite spots, it’s safe to say smallmouth bass are doing quite well in this particular lake.  Watch as one bass gets aggressive while Gretchen tries to collect rusty crayfish for her research. She says opportunistic bass would often grab her “samples” before she got a handle on them. Not this time, though!

Posted in Ecological Processes, Fish, Graduate Student Research, Invasive Species, Trout Lake Station | Tagged , , , , , , , , , , , , , , | 1 Comment

Madison Lakes Have an Early “Spring Cleaning”

Posted on April 18, 2012 by admin

The view along the Mendota shoreline shows the lake in its Spring "clear water" phase Photo: Adam Hinterthuer

If you head down to the shore of Lake Mendota today, you’ll notice you can see right down to the bottom. In fact, the current Secchi reading is seven meters, meaning you can get a clear view of Lake Mendota’s depths more than 20 feet down.

At first glance, it might seem that there’s just not much going on down there, but Lake Mendota is actually teeming with life and right in the middle of an algae bloom.

So what gives on the clear water?

The secret to our currently crystal-clear lake is a tiny zooplankton called Daphnia pulicaria.

While conditions are ideal for some species of algae, like fast-growing diatoms, to thrive, the current cool, highly-oxygenated water is also perfect for Daphnia pulicaria, which are voracious grazers of these kinds of algae.

Daphnia pulicaria Photo: The Wilson Lab at Auburn University

According to CFL research specialist, Ted Bier,  this kind of algae means good eats for daphnia and, right now, “they’re gobbling it up as fast as it’s growing.”

Bier says that, in its current state, the lake’s food web is humming right along. Nutrients in the water are consumed by the algae, which are then eaten by Daphnia that then become food for fish, efficiently passing nutrients right up the chain.

But, Bier says, there’s no way to know how long it’ll last. “Two years ago clear water only lasted 36 hours,” he says, thanks to a big rainstorm followed by baking temperatures. “Last year it was two weeks. We’ve had it last as long as two months.”

From left to right: water samples from March 15, April 1 and April 15 show the spring daphnia pulicaria population bloom in Lake Mendota Photo: Adam Hinterthuer

The current clear-water state is happening a bit earlier than average. Bier’s been taking samples each spring for ten years and the first big lake clearing is usually sometime around mid May.

Thanks to this year’s early lake warming and the last couple of weeks of cool, windy, dry weather – conditions are perfect for the annual early algae bloom and subsequent daphnia pulicaria feast. But, if we have a week of high temperatures or a big rain event that flushes a lot of nutrients into the lakes, a different kind of algae, called blue green or cyanobacteria, will begin to take over and we can kiss the clear water phase goodbye. Daphnia just don’t graze on blue green algae with the same relish and head to cooler, deeper waters once the lake warms.

Whatever window of clear water we do get this year, we can thank a little tiny zooplankton that’s a crucial component to our lakes’ water quality and is currently teeming right before our eyes – even if we can’t quite see it.

 

Posted in Ecological Processes, Global Change & Long-Term Ecology, Hasler Lab, Water Quality, Hydrology & Nutrients | Tagged , , , , , | 3 Comments

Freshwater Futures – LTER Short Film Series

Posted on April 16, 2012 by admin

Check out this new trailer for a series of short films chronicling the research being done as part of the National Science Foundation’s Long-Term Ecological Research program (LTER). You may recognize some shots of Center for Limnology equipment, as we conduct the Northern Temperate Lakes LTER research right here in Wisconsin!

The video was made by a non-profit called Freshwaters Illustrated. Their mission is to promote aquatic awareness through video, photography and film. Beautiful stuff!

 

Posted in Ecological Processes, Global Change & Long-Term Ecology, Water Quality, Hydrology & Nutrients | Tagged , , , , , , | 1 Comment

We Have Liftoff on the Crystal Mixing Project

Posted on April 6, 2012 by admin

A group gathers next to a deflated GELI on the shore of Crystal Lake to hear about the mixing experiment

Over the last three years a group of CFL students, professors and staff have worked on an experiment near Trout Lake Station that, they hope, will eradicate rainbow smelt and restore populations of native fish, like yellow perch, bluegill and largemouth to Crystal Lake. The experiment is finally ready to go.

As the early melt in March sent fishermen and boaters scrambling for their gear, members of the Crystal Lake Mixing project, also hurried to get their equipment in place.

“We flipped the switch [on Wednesday],” says Jordan Read, “and plan to leave it running. So far it’s looking good and things are moving along pretty well.”

PhD candidate, Jordan Read, explains how GELIs will mix the lake

Read, a PhD candidate in civil and environmental engineering at the University of Wisconsin-Madison, is one of the lead researchers on the project. Along with his colleagues, he’s built what looks like an armada of trampolines in the middle of Crystal Lake. They’re called “gradual entrainment lake inverters,” or GELI’s for short, and they’re hooked up to a bank of air compressors on the shore that, when controlled by a central computer, will send GELIs rising to the surface of Crystal Lake and sinking to the bottom throughout the summer.

You can read more and get real-time Crystal Lake data here.

The GELIs were designed to mix the entire water column and prevent Crystal Lake from stratifying this summer. That would keep the cold bottom layer of water from forming and, hopefully, make the lake too warm for the cold-water smelt to survive. The mixing won’t hurt native fish, since they’re all warm-water species.

Rainbow smelt are originally from saltwater habitats. They were brought to Michigan as forage fish for stocked salmon populations and soon escaped into the Great Lakes. Smelt became a popular table fish for some fishermen and researchers think they entered inland Wisconsin lakes via illegal stocking or in nets that hadn’t been properly cleaned.

Zach Lawson describes how the invasive smelt disrupt Crystal Lake's native fish populations

With an estimated smelt population of over 200,000 fish, a sudden die off could be quite obvious. If the experiment is successful, says Zach Lawson, a research assistant at Trout Lake Station, one sign may be dead smelt washing up on the beach.

“It’s a pretty common concern of people,” he says. “But you have to keep in mind that we are out there every morning before 9 am starting work, monitoring and maintaining GELI’s , and sampling. We’re out there every day, so we should be there to see anything that happens.”

And, Lawson says, it would be a short-term problem. A team of students and staff at Trout Lake Station are “on call” all summer to take care of any problems.

In other words, summer undergraduates should have shovels at the ready and wait for the call of – “Clean up on Crystal Beach!”

Watch the video of the creation of the Crystal Mixing project below:

 

 

Posted in Ecological Processes, Fish, Invasive Species, Trout Lake Station | Tagged , , , , , , , | Leave a comment

The Summer of ’59: Chasing White Bass Across Mendota

Posted on March 27, 2012 by admin

The pier is in. The ice is off. Fish migrations are already underway. And that means that the “open water” field season at the Center for Limnology is about to begin. Before I start filling this blog up with engaging posts about our exciting research, though, I thought I’d take a moment to look back at field seasons gone by.

Tom Mohs Photo courtesy of Placon Corp.

The following Q & A is with Tom Mohs, a Madisonian who has done quite well for himself in the field of plastic packaging. The UW-Madison mechanical engineering grad founded Placon Corp. in 1966. The company is still going strong and Tom serves as chairman of the board. But, for one memorable summer in 1959, Tom Mohs took a break from mechanical engineering and dipped a toe into another field – limnology. I’ll let him take it from here:

What brought you to the CFL as an undergraduate?

At the time, I was a student in the school of engineering studying mechanical engineering and I learned about the opening from my brother, Fred Mohs, who had worked for the limnology lab the previous two years. Back then the lab was where Hoofers, the little red building, is now. And I should add that Dr. Hasler (namesake of our lab and one of the founding fathers of the CFL) was a very good friend of my father’s. And we’d gone on a number of outings with the Haslers on some occasions in university boats. I believe that my Dad and Dr. Hasler even jointly owned a boat at one time.

So, what did you do all summer?

Researchers on a modified pontoon boat in Lake Mendota

One of the research projects Horrall (MS ’56, PhD ’61) was working on involved using a purse seine. At the crack of dawn or slightly before dawn, we were stationed between Picnic Point and Second Point and we’d find a school of white bass that was feeding on the surface. I would drive the barge, if you want to call it that, and somebody in a smaller outboard boat would go around the school and encircle it with the purse seine.

We’d bring the fish in and, generally, we’d get about 150 white bass each time. We’d put them in tanks and I’d drive the barge over to the other side of the lake over near Governor’s Island and, while we were heading over there, the fish were tagged on their dorsal fins and then we’d release them. Horrall was looking at whether the schools would stay together and how long it took them to get back to their original location. It was a lot of work and we did it about once a week.

What did Horrall find?

To the best of my knowledge, it wasn’t very successful. I think about only two fish were retrieved and one of those was dead!

Researchers demonstrating fish tagging with white bass

Were you involved in any other projects?

We also had a fike net over near Governor Island and we’d net fish and a few soft shell turtles and we’d log what fish were caught and then release them. So that was something we’d do a couple days a week. Other than that I don’t remember. I know I did a lot of repairing of nets!

I assume you enjoyed yourself, though?

It was a great job. I grew up on the (Madison) lakes and boating was my passion even then and it was something I really enjoyed. Driving the barge with the two engines, I felt that I could control it as well as any ship captain. I loved bringing it in and docking it perfectly with one engine going forward and the other backward.

Did the experience make you reconsider your chosen field?

I wasn’t swayed in the least! But my decision to go from West High School in Madison to mechanical engineering (at the UW) was about as automatic as going from 3rd grade to 4th grade. I was very mechanically inclined.

Okay, so not even a nibble on the career change question. Are there any fond recollections at least?

What I didn’t mention is when we gathered the 150 or so white bass, along at the same time we generally caught about an equal number of jumbo perch which had to be sacrificed because we wanted to get the bass into the nets without too much trauma. So the jumbo perch were, of course, filleted and we had a nice cookout at the end of the summer on Picnic Point. Had we been able to release them we would’ve, but they were caught in the net by the gills and it simply wasn’t practical.

Other than that it was just a marvelous congenial atmosphere. Ross was just a wonderful person to be with and it was a lot of fun.

Posted in CFL History, Fish, Hasler Lab, Q&A | Tagged , , , , , , | 1 Comment

Ice Off, Dock In

Posted on March 21, 2012 by admin

CFL's Unofficial "Dock Installation Crew" 2012. Photo: Adam Hinterthuer

Yesterday afternoon, eight brave souls decided to abandon their desks and help CFL facility manager, Dave Harring, put the Hasler Lab dock out into Lake Mendota. It was an unusual sight for March 20th to say the least – 80 degree weather, crew boats gliding past us on the water – but it appears field season is starting early this year for all CFL researchers who prefer the open water. Harring says this is easily the “earliest we’ve ever put the dock in. Usually I’m scrambling [to get the dock in] when students start wanting to use it for labs and sampling sometime in April.” (Also of note yesterday – Trout Lake Station was witnessing its earliest ice off in history)

The mechanics of installing the dock still elude definition, but I’ll try to elaborate with the slideshow below:

(If you’re having trouble seeing the captions, try watching from the CFL YouTube channel)

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And….We Have Ice-Off

Posted on March 13, 2012 by admin

While it wasn’t a record-setting early date for Lake Mendota to return to its more, um, liquid state this year, the official March 10th “ice-off” date is right in line with the long term trend that’s moving Mendota’s typical melt date from early April (as was the norm 100 years ago) to early March over the last couple of decades. You can check out the historical graph here, thanks to our North Temperate Lakes Long Term Ecological Research data. You can also hit “play” on the video below from some cool time-lapse footage from Saturday’s big melt. (Courtesy of the UW-Madison Department of Atmospheric and Oceanic Sciences and their rooftop camera!)

 

 

Posted in Uncategorized | 2 Comments

Sorry, Mendota, Trout Lake Has the “Good” Ice

Posted on March 8, 2012 by admin

Ice thickness on Lake Mendota was 17 centimeters on Feb. 29th. Photo: Adam Hinterthuer

Last week, I ventured out on the ice of Lake Mendota as Ted Bier, senior research specialist for the North Temperate Lakes Long Term Ecological Research study (LTER), drilled through the ice to take samples in the open water below. Bier mentioned that the ice, at 17 centimeters thick, was thinner than usual, but I still felt pretty good about the ice under my feet.

 

This block of ice was cut out of Trout Lake on March 7th. Photo: Adam Hinterthuer

Turns out that THIS is what “good” winter ice looks like. Even though it was 10 degrees Celsius (50 F) and raining out on my drive up north to outside of Minocqua, Wisconsin, turns out there’s plenty of ice left on the lakes. CFL staff cut this block out of Trout Lake today that’s somewhere in the ballpark of 50 centimeters thick. The ice will be part of an activity to kick off the LTER Schoolyard program. Trout Lake is another LTER sampling site and, tomorrow, we’ll welcome 40 middle school students from across the region to get out on the ice to take secchi depths, light readings, plankton tows and other forms of winter limnological research.

 

Ice from Trout Lake (left) and Trout Bog (right) Photo: Adam Hinterthuer

First, though, they’ll explore why and how ice forms and learn why the block of ice on the left (Trout Lake) looks so different from the block of ice on the right (Trout Bog).

Stay tuned for answers on that and details on what we find beneath the ice way up north. Until then, I’ll keep marveling at the clarity of “good ice.” No offense to Lake Mendota, but I’ll feel a lot more secure standing around on Trout tomorrow!

Ice block cut from Trout Lake, March 7th. Photo: Adam Hinterthuer

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