by Riley Steinbrenner
“Just a little bit more!” UW-Madison undergrad, Ishita Aghi, yelled from the front end of the electrofishing boat as Matt Chotlos, another UW undergrad, slowly backed up the only diesel fleet truck on station until the hitch met the boat’s trailer.
With three box headlights, a guard rail and two sets of five electrodes that dangled from the bow, the electrofishing boat was intimidating. Although lifeless sitting by the station’s garage, it demanded the most attention out of the other smaller motor boats that line the lot.
I checked my watch: just a little past 7 o’clock. The mid-July summer evening still provided enough sun for the bass-walleye crew to prep for their first electrofishing outing this month.
“It takes us about an hour to get ready,” Ishita explained to me as Matt and CFL graduate student Vince Butitta—visiting the station from Madison with UW undergrad Liddy Ginther—anchored the boat to the truck. “We usually leave station around 8.”
In front of the House of Lords, which stores all the equipment that research teams use for their field work, Holly Embke and Martin Perales—Center for Limnology grad students and head honchos of the bass-walleye crew—stood behind a second fleet truck loaded with buckets, nets and bins spewing plastic tubes while triple checking their list for the six-hour night excursion—which would start at 10pm.
Tonight, the crew was heading out to do their monthly electrofishing sampling on McDermott Lake. Not wanting to pass up on the opportunity to cross off the first item on my TLS bucket list, I joined the 43-minute parade of fleet trucks down Highways 51, 47 and 182 until we reached the experimental lake in Iron County.
The bass-walleye crew are working on a whole-lake experiment in Iron County to observe if reducing bass and sunfish populations has an effect on walleye populations.
Before they start changing fish populations in McDermott Lake, however, a baseline of the lake’s ecosystem—as well as that of Sandy Beach, their control lake—must be established.
Think of it like taking a pre-test and post-test for a math class. Before taking the class, your teacher makes you take a pre-test to establish your baseline knowledge in algebra. At the end of the school year, you take a post-test to see how your knowledge of algebra has changed—hopefully for the better.
For the bass-walleye crew, establishing the baseline means that they’ll be collecting data on all the fish trapped from several locations around their two study lakes.
Since different types of fish are susceptible to different trapping methods, just one trapping method would not be sufficient in getting a “snapshot” of the lake’s ecosystem. Therefore, they’re electrofishing, mini-Fyke netting, seine netting and clover trapping at predetermined locations around their two study lakes once a month.
The data they collect include the type of fish species and quantity of species, as well as length and weight of each fish per site. For some fish important to piecing together the lakes’ food web interactions, they will be collecting diets and flesh samples.
After they finish the experiment next summer, they will collect the same data at the same locations in both lakes using the same trapping methods. This will allow Holly and Martin to see exactly how the ecosystem changed. More importantly, they hope to answer the question: How did the population of walleye change after removing a main competitor, largemouth bass?
BEEEP. BEEEEP. BEEEEP.
“I’m…uuhhh…a little nervous,” Liddy confessed over the less-than-harmonious background vocals of Martin’s truck launching the electrofishing boat into McDermott.
“It’s ok, it’s my first time too!” I replied, comforted that someone sharing this adventure was in the same boat — literally and figuratively.
“Who’s coming along? You two and Vince?” Martin’s silhouette asked Liddy and me, standing on the now-docked electrofishing boat that looked like it came out of a Transformers movie.
“Don’t tell Martin I spilled his Red Bull,” Vince whispered before we lined up to squeeze in between the boat’s guardrails.
By the time we made it out on the lake it was half past 9, and the cotton candy pink and blue clouds had lost their saturation in front of the drowning sun, which Liddy and I had mistaken a house aglow on the shoreline for.
“How do people here feel about you experimenting with their lake?” I ask Martin as we stalk around the lake in this monster of a boat.
“Those guys like us,” Martin said, pointing to the jack-o-lantern house. “Overall, it’s been well-received. We had public input on choosing the [experimental and control] lakes.”
The process for choosing the lakes took about six months, but, since the Northern Temperate Lakes Region has suffered a decline in walleye populations for a while, there’s a lot of public support for anything that may help answer what’s going on.
“Ok, it’s about to get loud here,” Martin told us as he flipped the switch on the generator sitting next to him, powering up the electrodes attached to the boat.
“Once we start going, you guys are going to step on those yellow mats,” he explained to Liddy as she and Vince assumed position at the bow of the boat with rubber-gloved hands wielding a seven-foot net. “They’re pressure-activated, so as long as you stay on there, it’s live.”
Needless to say, “it” was the metal snakes of electricity swimming in the water.
“The electricity radiates from the electrodes,” Vince explained, “And it extends all the way back about a third of the boat. So, keep your hands in.”
Electrofishing temporarily paralyzes fish who swim near the “live” electrodes, causing them to float to the surface for easy retrieval. Once dumped into the livewell—a compartment in the boat to hold an angler’s catch—the fish regains movement, unharmed. This process only works, however, if the lake has good conductivity, and in turn just the right amount of voltage is applied.
Taking a spot in the back, I watched as Vince gave Liddy a quick run through of the pick-up fish operation.
“When I get a fish I swing the net over the side and dump it into the livewell,” he said, pointing to the mini pool of aerated lake water, lit by a flashlight duct-taped to its opened cover. “You’ll figure out your own scooping technique pretty quickly.”
“It’s 9:50,” Martin said from the control station as he prepared to monitor the boat’s speed and voltage of electricity created by the electrodes. “We can start now.”
After recording the location and timestamp, he consulted the Google Earth map of McDermott Lake, outlined with disjointed red lines to mark predetermined transects, or locations, where the team would sample.
“We’ll do the first transect for ten minutes, then return the fish to Holly, Matt and Ishita on shore for measurements. Just be sure to catch all the fish you can.”
And just like that, it began. Like the opening scene of a Broadway play, the three box headlights put the murky water in front of us on spotlight as we cruised along the lake’s littoral zone—just off of the shoreline—making the lily pads look as if they glowed in the dark.
Both Vince and Liddy searched the waters below them, their headlamps bobbing back and forth. Back and forth.
“See anything?” Martin yelled over the rumbling generator from the stern.
“Not yet!” Vince yelled back, gripping the net. Meanwhile, Liddy’s eyes were glued to the surface.
I look around to see, well, nothing. By now, we were in total darkness, expect for the boat’s headlights that guided us along. Every property on the lakefront had gone to bed, even jack-o-lantern house.
“Now they’re comin’ up!” I heard right before dodging the end of a retrieval net. Vince swung it over the guardrail, plopping a stunned northern pike into the livewell.
After that first pike, the only thing Vince and Liddy didn’t catch was a break.
As the pair continued, their nets weaved back and forth between the water and livewell like giant sewing needles, slowly filling the livewell with zombie fish that came back to life after a few seconds of paralysis.
Checking his timer, Martin waited until the seconds climbed to 59 after the ninth minute. One second later, he cut the generator. Game over.
“Alright, time to head back,” he said.
“So, it’s ten minutes of electrofishing?” I asked.
“Yeah, that’s the amount of time we sample for all eight transects around this lake and Sandy Beach, just to keep it consistent.”
Back at shore, a tall silhouette bearing a headlamp approached our boat with another bucket.
“Catch a lot?” Matt asked as Martin handed him a fresh McDermott transect number one sample, his headlamp catching the silhouettes of the now very lively fish swimming around in the bucket.
“Oh, don’t forget this one!” Vince said, reaching down outside the livewell to pick up a juvenile sunfish gone rogue, and plopped it in with the rest before Matt took the sample back for taking measurements of each fish—length, weight, species and, occasionally, tissue samples and diets, before releasing them back into the water.
Going out for round two, I sat in-between the two yellow mats with Vince to my left and Liddy to my right, positioning my camera through the guardrails. Best seat on the boat!
When we reached the second transect, Martin switched on the generator.
“You guys ready?” he asked rhetorically. By now, Vince and Liddy were pros.
With the headlights from the bow beaming and nets flying, it was a whole new world seeing this happen from the platform.
Soon after we started cruising, the fish started to surface. Round Two had begun, and for Vince and Liddy, there were no time-outs. That’s the interesting part about electrofishing, the objective is to get as many fish as you can pull in without stopping, or else it would cause inconsistency in the data. And with about five to ten fish floating up to the surface at the same time, I understood why two people were needed.
During the adrenaline of this reverse game of “whack-a-mole,” time seemed to go by much faster, and soon enough their time was up.
“I’m starting to like this!” Liddy said with a smile as we turned towards the livewell to cash in their winnings.
Yellow perch. Pumpkinseeds. Bluegill. Not too shabby!
Heading back, Liddy continued to transfer the earnings to the bucket, while Vince rid of the macrophyte-hitchhikers in the livewell.
After we reached shore, Matt and Martin swapped buckets, switching the one full of samples with an empty one. Deciding it would be a good time to check out what Matt, Ishita and Holly were up to, I climbed up and over the guardrail and headed over to their makeshift lab of scales, rulers, nets and aerated tubs of lake water. It was just past 11pm.
Taking a break before the next transect, Martin, Vince and Liddy also made their way over to the table, which smoked with mosquito repellant.
Holly was prepping to take a gastric lavage, which is a fancy term for emptying the contents of an organism’s stomach to observe its diet—yum! Doing this, she said, gives a “snapshot” of what the fish has eaten in that moment.
Holding the bottle of water, Holly squeezed it into the fish’s mouth and it proceeded to puke up a stream of lake water. If witnessing a fish throw-up isn’t worthy enough of adding an eighth wonder of the world, I don’t know what is.
Next, Martin settled the walleye into a shallow, plastic basin. Grabbing a tool similar to a scalpel, he plunged it into the fish’s scales to get a tissue sample.
Tissue samples are another piece of data Holly and Martin collect from certain fish. By analyzing the tissue at a molecular level back in the lab, they will be able to see if the fish’s diet consisted of benthic—bottom-feeder—organisms or pelagic—open-water—organisms. This is important information to gather, along with the diets, as it will help Holly and Martin understand where the fish in McDermott Lake get their food.
Unlike diet samples, however, tissue samples create a more long-term view of what the fish consumes. This will help them create an accurate map of the overall food-web interactions in this ecosystem by determining which fish belong at which trophic level.
Think of creating a food web from these samples like putting together Russian nesting dolls. One doll is a bug, and inside that is algae—that’s the baseline of the food web, since your samples tell you the bug ate the algae. And then you have a doll that’s an herbivore—a plant-eating organism—but it has to be at least two dolls bigger than the fly because the herbivore can’t eat a fly, and the puzzle continues.
“Essentially, we’re trying to find out who fits in where and what they’re doing,” Holly said.
After retrieving the tissue, Holly stored the sample and reached for a tube of liquid bandage to dress the walleye’s wound. Like two surgeons in the operating room, Holly handed the bottle off to Martin. He focused his headlamp on the fish’s scales and steadied his hand to seal the spot on the walleye’s back.
Once approved for release, Matt lifted the world’s best patient from its basin and sent it back home with a rad story of its second chance at life—better than a lollipop.
For the boat crew, break time was over. Martin, Vince and Liddy climbed back aboard SS E-Fish for round three of shock and awe.
As we saw them off, the electrodes dragged their metal fingers against the boat launch, not wanting to leave but having no choice as it slipped away into the darkness.
I now sat in the slightly drier, mosquito-infested lab of Holly, Matt and Ishita—that is, the incline of the boat launch ten feet from the shoreline. Luckily, no one was planning on rollin’ up with their pontoon for at least the next eight hours.
“Oh shoot,” Matt let out. I look closer to see his hands cupping down at different spots on the table sporadically like a fish out of water—which is exactly what was underneath his hands before passing it off to Holly.
“6.7,” she said as Ishita recorded its weight in grams.
Matt grabbed a mini net and reeled in a new fish from the aerated tub bubbling on the ground next to him.
“Yellow perch. 140 millimeters,” while Ishita recorded the length, Matt passed it off to Holly, who carefully perched it on the scale.
After a several more minutes of weighing and measuring, Holly, Matt and Ishita finished recording data from the second-transect sample.
I check my watch, secretly excited to utilize the “light” button to actually read the time—11:59pm. After getting my fill of shock and awe, it was time to head by to station.
“So…how do I get back?” I ask the group.
“You go down this road out of the parking lot and take a right onto 182. At the end of that road take a left onto 47. Then a right and you’ll be on 51,” explained Ishita.
“…Ok—thanks!” I replied, not very confident in my ability to remember what way goes with which road in the middle of the night and make it to Trout Lake Station.
But, 43 minutes later, I did.