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Scanning Shallow for Blue Catfish

Scanning Shallow for Blue Catfish

One thing a 40-pound freshwater fish cannot do is hide. Three feet long and wide-bodied, with a hard skull and big air bladder, blue cats are good sonar targets. Pushed up into water that barely covers their backs, large groups of blue catfish show up on side-scan sonar, allowing anglers to anchor and fish slowly warming mudflats

Warming water temperatures bring bait and predators to shallow water at the upper ends of reservoirs and river systems in spring. From February to May, climbing temperatures eventually push out walleyes, white bass, and black bass to deeper areas, but blue cats stay until their spawn starts in June.

Set the depth highlight feature on your mapping software to cover 2 to 10 feet (5 feet if the water is stained) and head for the largest flat in the vicinity. The only thing standing between you and fish becomes the patience to pinpoint their location and confidence in today’s sonar technology.

Kansas, the Middle Ground

The Kansas Department of Wildlife and Parks started developing blue cat fisheries in 1990 to build on the local catfish angling culture and the desire for trophy fishing opportunities. Milford Reservoir started the trend and has been a destination for a decade, but other reservoirs recently joined the ranks. The Catfish Chasers tournament series uses the length of its eight-stop schedule to explore these new waters and the quality of the fish. On April 21, 2018, the tour stopped at Perry Reservoir in Northeast Kansas.

“A few years ago, a tournament at Perry reservoir would be dominated by channel catfish,” says Catfish Chaser’s organizer David Studebaker. “Top places this year included teams that landed multiple legal (35 inches or greater) blue catfish and the final position came down to an extra kicker channel cat on the scale.”

I joined Studebaker and his tournament partner Craig Collings before the event to gauge the blue cat size in different parts of the reservoir. Meeting at the Rock Creek Marina and Resort, we used a cast net to catch fresh bait. 2-D sonar indicated small concentrations of fish around the marina’s covered docks where Studebaker gathered 10 large shad and a 6-pound bigmouth buffalo. While each throw of the 8-foot, 1.5-lb-per-foot net landed only a couple of baitfish, it was easier to work the 10-foot depths of the marina instead of targeting larger schools of shad 25 feet deep in the windy channel. Each shad went on ice in a cooler and the buffalo went into the livewell.

Perry’s three major creek arms have excellent habitat for blue catfish. The main creek arm has a mile-wide flat that averages 4 feet deep. The other creek arms have smaller flats that also attract larger fish. By the end of the weekend, all three would play a major part in the tournament results.

David Studebaker catches bait near a marina.

Checking out one of the smaller tributaries, David pointed out groups of carp, crappies, and blue catfish, using Structure Scan on his Lowrance HDS Carbon sonar unit. Even among the black triangles of standing timber, each species stood out. Crappies and white bass huddled together in large groups. Carp looked like catfish initially, but when we found the big blues the difference was obvious. Catfish were larger with huge shadows.

“The wide girth of these fish makes them easy to find, but generating a bite takes time,” Studebaker says. “Big fish feed on their own schedule and spend more time digesting than smaller fish. At other times of the year, big fish leave the area after feeding, but the relatively warm water (48°F to 50°F) is too comfortable to leave, so many of the groups are inactive.”

This situation leaves the best anglers focused on bite windows and monitoring fish activity throughout the day. After anchoring and casting the legal limit of nine cutbaits into the water, we sat in his Alumacraft and watched the tips of his Big Cat Fever rods. Within the hour we landed two fish right around the length limit.

Side-Scanning Precision

Humminbird released their initial Side Imaging sonar technology in 2002, with Lowrance Structure Scan and Garmin’s SideVü following shortly thereafter. The units feature two transducer crystals mounted to send a thin vertical beam right and left of the boat. Frequencies of 455 kHz and 800 kHz were standard until the release of 1,200-kHz (1.2-mHz) versions two years ago. The shallow water doesn’t demand the longer range of lower frequencies and the detail available at 1.2 mHz helps anglers positively identify target species. Compressed High Intensity Radar Pulse (CHIRP) technology further scans multiple frequencies before computer algorithms generate the best images.

Before this technology, 2-D sonar would not show fish in shallow water, so anglers had to drift to contact fish. Now, locating specific groups of big fish is possible, and even easy once the technology is trusted by the angler. Anchoring for fish is once again the best method.


Side-scan has always been useful in identifying brushpiles, rocks, vegetation, and schools of fish, while moving forward but, under anchor on a nondescript mudflat, the screen turns to generic static. Some anglers even turn off their sonar under anchor because they believe it affects fish movements and tendency to bite. The large size of blue cats presents a unique opportunity to use side-imaging for bait monitoring.

While double-anchored, the thin band of side-scan sonar creates an invisible net about 100 feet to each side of the boat. While fishing with Studebaker, I watched as toothpick-like streaks moved across the screen, giving us confidence to extend our stay. Smaller predators like a single walleye would barely make a mark, but again, blue catfish, with their wide shadow, cannot be mistaken. Eventually, bites closed the loop and confirmed the sonar information.

Capital Catfish

Similar in territory, the Potomac River mudflats from Washington, D.C. down to Mount Vernon and beyond operate much the same as heartland reservoirs. Fish stay in the deeper channels during the coldest months, but even the slightest nudge upward in water temperature moves cats to feed shallow. The main difference is that these tidal flats grow acres of grass.

This grass generally prevents targeting specific groups of fish on sonar, but there are other strategies that are just as effective involving depressions, grasslines, drop-offs, and bait. It helps that the area has been booming with catfish.


Captain Jason Kintner runs Capital Catfishing Guide Service and relies on efficiency to narrow down his search. “The current in a river is the largest concern,” he says. “Big fish find the smallest depressions for relief from consistent flow and daily tidal fluctuations. Search flats for changes in depth, grasslines, rocks, concrete, or any other minor break. Mark as many of these spots as possible and then spend time on them to gauge fish activity. Don’t be afraid to fish shallow. Baitfish activity is the best sign and can occur in less than a foot of water.”

Again, side-scanning technology helps in shallow areas by identifying harder-bottom depressions, cement, and rocks, which show up as large white spots on the screen. Double check the depth change with traditional 2-D sonar or keep an eye on the center section of the side-scan window for diverging lines. Outline the area with waypoints, quietly back off and anchor, then cast baits into and around the depression.

Kintner (and everyone in this article) uses slipsinker rigs exclusively for shallow catfish. Even in grass, floats have no use in the shallows and often push baits to the surface. An 8/0- to 10/0-circle (Eagle Claw L197), Kahle (Eagle Claw L141), or a combination of the two (Charlie Brown Octopus Circle) hook tied with a shock leader of 30- to 60-pound monofilament leads to a swivel, above which rides a 1- to 3-ounce sinker. All three anglers use Shimano Tekota reels with either 30-pound mono or 60-pound braid mainline. Braid is preferred for rocks, mono for areas with wood. Softer rod tips bend after tightening up to the sinker and help identify bites while also filtering out head shakes after hooking fish.

“Learning the river takes time and each spot has a tidal window twice a day,” Kintner says. “Moving water in the area spurs fish activity so use slack tides to search for new areas or take a lunch break.” Since the grass hides fish on sonar, Kintner anchors on a random spot to start. Active fish either find his baits quickly or he packs up hoping to run into a big group of fish at the next spot. “One day I pulled into a slight depression on a flat and landed five fish over 40 pounds in the next hour. If I had waited at my previous spot this wouldn’t have happened.”

For Kintner, an hour wait strikes the right balance. “Active big fish generally find baits in the first 30 minutes,” he says. “I stay an extra half hour to allow fish to cycle through and gauge the activity on the flat.” No action in an hour and he pulls anchor. If the flat has the right water conditions the move might be 100 yards to the next depression looking for a holed-up school of fish. At the end of a tide cycle the move is farther. Working four to six spots in a trip builds confidence in a section of river or pushes the guide to explore a different area the next day. After three to four days, key movements and locations of the fish emerge, increasing his success.

The blue catfish is an introduced species in the Potomac and considered invasive by some, and multiple groups are working together to balance the ecosystem of over 100 species of fish. Major changes include commercial harvest and water-quality improvements. Kintner has a unique take on the situation: “As a guide for trophy fish, I see and understand the importance of commercial fishermen removing smaller, table-fare fish for market and to keep the population in check. Virginia, Washington, D.C., and Maryland are all promoting the health benefits of blue catfish and restaurants are serving the fish on their menus.  Along with most other river systems, smaller fish (under 10 pounds) are the safest and healthiest to eat.” He says that the American shad population has exceeded goals for restoration, the grass growth has returned, and the largemouth bass spawn has been successful in the past two years. “It’s only a matter of time before the Potomac sees a big-money catfish tournament, similar to the bass tournaments regularly held in the area,” he says.

Lake Tawakoni

This 37,879-acre reservoir an hour east of Dallas includes three creek arms tailor-made for blue catfish. The large feeding areas allow more fish to grow and thrive, but also intimidate anglers due to sheer size. Before side-viewing sonar, anglers were forced to drift and search. Now they can pinpoint specific pods of giants.

Guide Michael Littlejohn sees the winter patterns end in late February. “As soon as big schools of threadfin and gizzard shad sense a warming trend they bolt for the shallow inlets and don’t return deep,” he says. One year he tracked the bait and it moved 15 miles from the dam to the inlets in a long weekend. From there, March cold fronts reduce bait and gamefish activity instead of forcing a retreat back to deeper water. By deep, Littlejohn means 5 feet or more.

Captain Michael Littlejohn thinks the Tawakoni lake record of 87.5 pounds caught in 2014 will be broken soon.

From March until the late June spawn, the large flats make finding big fish a challenge, but the experience is the same as in Kansas: use side-scanning sonar to locate one of the hundreds of herds of big fish, then work to see if they will bite. The first step is to track the wind direction to narrow down the potential location of bait. From there, Littlejohn cruises silted-in creek channels, explores downed timber, and pokes around standing hedgerows looking for fish. “Clients are surprised, but it sometimes takes one or two hours of idling to find a group of fish at Tawakoni,” he says. “I know fish are there, so I keep looking until I find them. When we locate a school, clients settle down and fish hard because the sonar returns are convincing.”

After finding fish, Littlejohn trusts his Minn-Kota Spot-Lock to keep the boat in place while quietly setting up a sturdy double anchor. “I would use Talons and other pole-style anchors but the wind on shallow Tawakoni flats can exceed their holding strength,” he says. “Practicing so that traditional anchors can be set in short order sets an advanced angler apart.”

Standard 8/0 circle-hook slipsinker rigs with fresh cut shad are set at various directions and distances from the boat. Littlejohn uses 8-foot Ugly Stik Catfish rods (USCACAT802MH) with Shimano Tekota reels. “Nibbles and flexing rod tips indicate channel cats in the area. Blue catfish bites, however, are impossible to miss. They bend rods deep and pull drags.”

Blue catfish are native to the rivers in Texas but the stocking program in 1989 created the fishery at Tawakoni. The lake record of 87.5 pounds was caught in 2014, and Littlejohn expects that to be broken again in the next couple of seasons. Now is the time to learn these techniques and apply them.

All three anglers search, then anchor. Drifting works, but precision searching works better. Set a timer for 2 hours and idle the largest flats on your lake looking for fish. While an article can point out the basics, practicing these details is what separates a couple-fish-a-day angler from consistent success.

*David Harrison lives in Lawrence, Kansas, and has previously contributed to the Catfish In-Sider Guide. Contacts: Guide Jason Kintner, ­, 812/201-3399, Guide Michael Littlejohn, ­, 903/441-3937.

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