Researchers wire up Grand Forks catfish
GRAND FORKS — Mark Pegg needed 10 catfish from the Grand Fork stretch of the Red River. And he'd budgeted two days to catch them.
Yeah, right. ...
Turns out he needed less than four hours.
A fish ecologist and instructor at the University of Nebraska-Lincoln, Pegg was working with UNL grad student Henry Hansen, undergraduate senior McKenzie Hauger and local catfish guide Brad Durick to catch, tag and implant radio-transmitters in 10 catfish near Grand Forks.
As part of a multi-partner study with North Dakota, Minnesota and Canadian fisheries managers, Pegg and his students also tagged and put transmitters in 10 catfish near Fargo and five catfish near Drayton, N.D.
As Durick had predicted, the cats cooperated near Grand Forks on this breezy mid-May morning, and Pegg and his students wrapped up their work a few minutes after noon. Considering they had to catch the catfish, surgically implant the radio-transmitter tags behind a pectoral fin in each of those fish and insert numbered Floy tags—as they're called—near the dorsal fins, that was fast work.
More than half of those channel cats were in the teens, weight-wise, and a handful flirted with 20 pounds.
Once again, the Red River was living up to its reputation as one of the best channel catfish fisheries on the planet.
"It's amazing," Pegg said of the Red. "It's pretty much spoiled us all for any other catfish, that's for sure."
Pegg has spent parts of the past few summers working on the Manitoba portion of the Red River as part of a project to learn more about channel catfish movements. The project, which launched in 2012, initially focused on tagging fish, and more than 15,000 channel catfish have been tagged since then.
The project in the past couple of years has expanded to surgically implanting the radio-transmitter tags. Manufactured by Vemco, a company specializing in telemetry equipment, the catfish transmitters cost about $300 each.
"We're using two techniques—we're using mark and recapture, where we put these Floy tags at the base of their dorsal fin. We're also doing surgeries and implanting these Vemco tags," said Hansen, a Mora, Minn., native and recent transfer from the University of Wisconsin-Stout. "It gives us two different scales for seeing movement all the way from Lake Winnipeg up to the Fargo area."
To track that movement, a network of receivers, or "listening stations," has been planted along the Red River from the source into Lake Winnipeg and several tributaries to pick up signals from the radio-tagged fish.
About 200 listening stations will be anchored throughout the basin, Pegg said. The listening stations along the U.S. portion of the river are spread out about every 20 miles.
"It's a fairly large amount of listening stations," Pegg said. "There's a similar network in the Great Lakes that has a few more listening stations, but this is the largest one we know of in inland fresh water, not counting the Great Lakes.
"Once a year, we'll go back to those listening stations, pull them up, put in a new battery and drop them back down."
The Nebraska contingent is handling most of the catfish work, Pegg says, while Canada's Department of Fisheries and Oceans is working to implant transmitters in walleyes, lake sturgeon and bigmouth buffalo, a species of concern in Manitoba.
Other partners in the project include the Minnesota Department of Natural Resources, North Dakota Game and Fish Department, Manitoba Sustainable Development and the International Joint Commission, which is funding some of the telemetry equipment.
Last year, a grant from Manitoba's Fisheries Enhancement Fund paid for about 70 transmitters, Pegg said. By summer's end, about 160 channel cats will have radio-transmitters throughout the Red River, Lake Winnipeg and the Winnipeg River, he said.
Pegg and his students also put transmitters in 12 bigmouth buffalo while working the U.S. portion of the river and will return later this year to catch and wire up eight more of the rough fish, he said.
"All told, I think the plan for this summer is about 450 transmitters," Pegg said. "Mostly walleye, and a few catfish."
On the move
Each radio tag has a unique frequency and beeps at the listening station when the fish swims by, Pegg said. The listening station then makes a timestamp of the encounter that's available when the data is downloaded.
"We'll know when they moved through and in some cases, which direction," he said.
Based on tag returns and data downloaded to this point in the study, the fish are "going all over the place," Pegg said.
"Most of our transmitter work has been done in Manitoba, but we've had a couple of fish tagged at the dam at Lockport—one swam out into Lake Winnipeg, went all the way up to the narrows (between the south and north basins), swam back around and went back."
Officially known as the St. Andrews Lock and Dam, the Lockport Dam in Manitoba is about 30 miles north of Winnipeg and the last dam on the Red River before Lake Winnipeg.
The brutish Red River cats aren't afraid to swim upstream in fast current, either.
"We've had several fish that have swam up here" to Grand Forks, Pegg said. "We know with the Floy tagging we get a lot of fish that come here to the Grand Forks area."
Durick alone has had nearly 40 catfish tagged in Manitoba come into his boat in the past couple of years.
"Any time we get high water they shoot through Drayton and even Lockport," Pegg said. "They move through the dams and head upstream."
Picture of precision
Implanting the radio tags in the catfish is a process that begins with sedating the fish using a technique called electroanesthesia, a fancy word for stunning the fish with a jolt of electricity.
The fish recover from the jolt after a few minutes.
From the initial incision to the final suture, the process took less than 5 minutes per fish. The gills are kept wet throughout the procedure to minimize stress.
"Catfish are notorious for expelling anything internal, so we actually have to do an extra step with these fish that we normally don't have to do with other species," Pegg said. "They'll actually insert two strings around the bone right behind the gill flap and tie the transmitter down to that."
The transmitters are designed to last five to six years depending on the "beeping frequency," Pegg said, so the project will continue at least another two to three years, when the first transmitters installed begin to die.
What happens beyond that will depend on funding, Pegg said. Over time, the catfish will absorb the transmitters.
During their time in Grand Forks, the 10th and final catfish had been wired for sound and released, and the crew was packing up when the last fishing rod with bait in the water buckled over in its holder.
Hauger picked up the rod and started reeling. Judging by the rod bend, the fish was no slouch.
In a turn of events that couldn't have been scripted any more perfectly, the big cat wore two double tags behind its dorsal fin.
"Any of the double-taggers were tagged in Manitoba," Pegg said. A look at the database later that night confirmed the catfish had been tagged in July 2014 near Sugar Island on the Red River north of Selkirk, Man.—most likely by previous Nebraska students who worked on the project.
"Been out there for awhile!" Pegg said.
The excitement of catching the fish wasn't lost on Hauger. Catching a 34-inch catfish is cause for excitement in and of itself, but when you're a research student who lands a catfish tagged nearly three years earlier some 300 river miles downstream, the catch takes on added significance.
"Someone's buying me beer tonight," she said.