'Like opening a Christmas present,' survey reveals insights into Red River fish populations

Dec. 2—GRAND FORKS — Populations of channel catfish, walleyes and saugers are doing well on the U.S. portion of the Red River, based on the results of a riverwide assessment the Minnesota Department of Natural Resources conducted this past summer.

The DNR samples fish populations in the Red River every five years, dividing the survey into four reaches: Reach 1 near Wahpeton-Breckenridge, Reach 2 near Fargo, Reach 3 near Grand Forks downstream from Riverside Dam and Reach 4 from Drayton, N.D., to the Canadian border.

Crews from area DNR fisheries offices in Fergus Falls, Detroit Lakes and Baudette divvy up the workload, with Fergus Falls handling Reach 1, Detroit Lakes working Reach 2 and a crew from Baudette sampling fish in Reaches 3 and 4.

The assessment, which dates back to 1990, originally was scheduled for 2020, but the DNR postponed the survey until 2022 because of the COVID-19 pandemic.

For catfish — the target species for most anglers fishing the Red River and the primary focus of the survey — catch rates were considerably higher than the number sampled during previous surveys, said Nick Kludt, Red River fisheries specialist for the DNR based in Detroit Lakes.

In the Grand Forks stretch, for example, crews sampled an average of 8.3 channel cats using a measure called "Catch Per Unit of Effort" — or CPUE — compared with 2.0 during the previous survey in 2015. In the Wahpeton stretch, the CPUE was 153.3, compared with 40.3 in 2015.

High water and faster flows during the survey likely played a role in the catch rates, Kludt said. Faster current tends to trigger channel catfish to move upstream — for whatever reason.

"Those fish were up and moving, so they were more vulnerable to our gear," Kludt said. "Environmental conditions were just really conducive to sampling them this year."

As part of the survey, crews set 30 trap nets in the upper two reaches of the river, while a combination of 30 trap nets and 18 trotlines — each with 25 baited hooks — is used to sample the two downstream reaches.

Trotlines are the most effective gear for catching larger catfish, while trap nets catch a bit of everything.

The comparatively higher catch rates in the two upstream reaches are consistent with previous surveys, Kludt says. The river is narrower, and while catfish catches are higher, the fish are smaller, on average, than cats sampled farther downstream.

"It kind of fits with the grand ecological theory of rivers," Kludt said. "But there's also the little ghost in the data that we're more efficient at sampling smaller fish in the upper river than we are in the lower river.

"That being said, as a percentage of the population, we do see more bigger fish as you head toward Canada."

Crews this year sampled 27 different species along the U.S. portion of the Red, Kludt says, not including minnows or other species too small for the sampling gear to catch.

"I can honestly tell you that pulling trap nets is probably one of my favorite activities, just because it's a bit like opening a Christmas present in terms of the anticipation of, 'Well, what did we get this time?' " Kludt said. "And it's really pretty enjoyable. But then on the back end, crunching the data is also really interesting, because then it's kind of fleshing out the picture of 'What does it all mean? How does it fit into the story of the river as you've sampled it?' "

The abundance of fish in some of the trap nets was actually problematic, at times, "from a getting the net out of the water standpoint," Kludt says.

"The sheer weight of a net with 675 channel cats in it — you can have three crew (members) in a boat, and that is still an absolute bearcat to try and get into the boat," he said. "So, that was quite interesting."

Another takeaway from this year's survey, Kludt says, is that catfish production and year-classes — the number of fish recruited to the population from a particular year's hatch — are holding steady.

"We have pretty consistent year-classes through time, and that trend is definitely continuing, based on this year's data," he said.

High water delayed the start of this year's survey, which began the second week in June near Wahpeton and wrapped up the second week in July near the Canadian border. Catfish appeared to be spawning during the Grand Forks portion of the survey, Kludt says. Catch rates were high, but the average size was down.

Anglers fishing the Grand Forks stretch of river during the same time had similar observations, he says. Then, a significant rainfall that resulted in "a big slug of water moving through the system" dropped water temperatures and put the fish back in pre-spawn mode.

That triggered bigger cats to go on a feeding frenzy, and the Scheels Boundary Battle Catfish Tournament in late June saw the heaviest weights in tournament history, Kludt says — by far. Teams could weigh in three catfish daily — two larger than 24 inches and one "slot fish" less than 24 inches.

"If you look at the average of the top 10 bags for the previous two tournaments in '20 and '21, it was 63.3 and 62.1 pounds," he said. "In 2022, it was 70.8, so the fish flipped a switch and it was definitely on."

Catfish growth rates on the Red River also are consistent with previous surveys, Kludt says. Catfish on the Red grow slow and don't reach sexual maturity until about age 10, at which time they're about 20 inches long.

On the upside, harvest pressure is light, and catfish in the Red are long-lived.

"A lot of the fish that are caught and harvested are sexually immature fish," Kludt said. "And if you have really high fishing pressure, that obviously can create quite a problem. But given that our harvest pressure remains fairly low on the Red River, that really insulates the population from that potential problem."

The North Dakota Game and Fish Department funded a creel survey this past summer on the Red, but results won't be available until later this winter, said Todd Caspers, northeast district fisheries biologist for Game and Fish in Devils Lake.

"We still see very strong size-class numbers for those large trophy catfish that people are going for, in a lot of cases, based on the creel data in the lower river," Kludt said, referring to downstream portions of the Red. "However, there's still a good chance of you tying into one of those fish in the Fargo and Wahpeton area, as well. The only thing you're going to have to contend with is there are a lot more (smaller) fish that you're going to have to wade through. So, your catch rate is probably going to be higher."

Kludt sums up Red River catfish populations like this:

"Our size structure remains strong, our reproduction is consistent and growth remains steady," he said. "We have a strong population, and in all respects, it continues to be strong."

Walleyes in the Red River don't get the notoriety of channel catfish, and while they might be a secondary species, the population is doing quite well, Kludt says. The number of walleyes sampled was about five times higher than the previous survey in 2015, he says.

Walleyes in the Red averaged 15 inches long in the summer survey, Kludt said, but there's always a chance at catching a trophy-size fish.

The bulk of the fishing pressure for walleyes in the Red occurs in the spring and fall.

"The big takeaway for me is that we had a nice abundance" of walleyes, Kludt said. "We see evidence of consistent year-class production within our walleye population, with a real strong peak in our length frequency data right around that 15-inch mark.

"And it does appear, based on preliminary looks at the data, that we probably have another year-class following that one up that will support our (walleye) fishery into the next few years, as this one kind of naturally declines with natural mortality and fishing pressure."

Saugers — a smaller cousin to the walleye — were down slightly, Kludt says, but remained "pretty consistent" when compared with 2015.

"We were down a little this year, but nothing that is outside the realm of sampling variability," Kludt said. "We have a really good sauger resource out there. And we have a lot of sauger in that 12- to 16-inch range right now. That's another resource that, again, you see people kind of incidentally getting them, but I don't know many guys that are out there actually targeting sauger."

Among other species sampled, freshwater drum and quillback — a sucker species — also were abundant, Kludt says.

"Everything went well, everything went safely, and it's nice to see the fishery in good shape," he said.