Fishing Man Made Structures for Catfish
June 04, 2014
Big River Habitat
Big rivers are far different today than they were when the first settlers arrived. Flood plains that once stretched miles on both sides of these great waterways have been severed by levees that line the banks for thousands of miles. Dams on the upper Missouri and Mississippi rivers, and the entire length of the Ohio, now control the ebb and flow of water levels.
Most dramatic of all are the changes to the river channel. The naturally shifting course of the river, which once changed dramatically from one year to the next, now is controlled (as much as possible) by the Army Corps of Engineers. The Corps' fingerprints are visible everywhere on big rivers, in the form of structures built to maintain a navigable channel for barges.
Big rivers still harbor big cats, though. Some biologists, in fact, believe that some river sections like the middle and lower Ohio may support more big cats today than before the dams were built. Lock and dam structures transformed relatively shallow river stretches into a series of deeper pools, increasing the quantity and quality of catfish habitat.
The challenge big river anglers face — the same challenge Moyer, Eckholm, and I encountered on the Mississippi River below Alton — is to understand how catfish relate to these manmade structures. Truth is, fishing a bridge pillar the size of a house isn't so different from fishing a snag or a boulder on a smaller stream. The scale is larger, but so is the top-end size of the fish.
Manmade structures like wing dams are particularly important on channelized rivers like the lower Mississippi and Missouri. Snags and brush — the primary habitat on smaller rivers — are routinely removed from big rivers, and oxbows, side channels, and sloughs are sealed from the main river. A deep, swift, and turbid barge highway results, with wing dams as the primary catfish habitat.
A study of the use of wing dams by catfish on the Missouri River, conducted by the Missouri Department of Conservation, revealed that active flatheads prefer to hold along the edge where fast and slow currents meet. The most distinct current edges on wing dams occur at the tip of the dam, where fast water from the main channel pours over the slack water behind the dike, and behind low spots atop the dam.
Channel cats prefer similar feeding stations, but in rivers containing flatheads and blue cats, smaller channels are forced into less opportune areas. Most of the channel cats sampled in the Missouri River, for example, were found near snags and riprap along the eroded mud banks in front of wing dams. Blue cats were evenly split between snags and the tips of wing dams.
Biologists caught few fish in the deep slack water behind wing dams, but speculate that could be the result of inefficient sampling gear rather than habitat preference. In our experience, inactive cats tend to favor the deep scour holes behind wing dams during normal water levels from late spring through early fall. In colder water, though, active fish also favor these slack-water holding areas.
Most of the blue cats Moyer and company caught on the Missouri River before Eckholm and I hit the scene were holding at the head of the scour hole at the tip of the wing dam. Moyer used a three-way rig with 6- to 12-inch dropper line anchored by a 6- to 8-ounce bank sinker. The leader was about two to three feet long, and terminated in a 10/0 Gamakatsu Octopus hook.
Fresh cutbait usually is a better choice than frozen bait, but large gizzard shad and goldeye were difficult to find. Fortunately, Moyer had brought several pounds of skipjack herring fillets from Tennessee, which were nearly as effective as fresh bait. The "Basic Systems" column in this issue provides more information about three-way rigs, while "Baitman's Corner" illustrates Moyer's method for catching and preparing skipjack herring.
We didn't fish the tailrace below Alton Dam during our three-day visit, but it probably would have been a good option. Tailrace areas hold some catfish all year, but the population peaks during spring and early summer when the upstream migration of prespawn catfish is blocked by dams.
On major rivers like the Ohio and the upper Mississippi, lock and dam structures segment the stream into pools from about 10 to 90 miles long. In the tailraces below these dams, cats consume baitfish killed or injured when they pass over the dam or through the lock. They also feed on skipjack herring, shad, and other species that school in the upper level of the water column.
In long river stretches, fresh waves of fish continue to reach tailraces for several weeks, sustaining the bite as resident fish are harvested. The best tailraces lie at the heads of long pools, particularly if large tributaries and major current breaks don't divert a portion of the catfish population. Blue cats, though, usually bypass holding areas that attract large numbers of channel cats and flatheads.
All catfish species favor well-oxygenated water with a steady supply of living or dead baitfish, but cats seldom hold in fast current. Instead, they seek edges formed by currents moving in different directions, or where current flows of different speeds and volumes merge. The edges form tunnels near the bottom — areas of relative calm in otherwise turbulent water.
Catfish move easily through these tunnels, searching for baitfish or other food items washing through the tailrace. The best current tunnels usually are found where flows of different volumes meet below the dam. If a pillar separates two dam gates, one running water and one closed, the pillar creates a current edge where a large volume of water from the open gate runs over a lesser volume moving in the same direction.
Current tunnels, though, usually don't coincide with the visible current edge on the surface. Surface currents move much faster than water near the bottom. This allows the faster flow to run farther over the slower flow on the surface than on the bottom. The best way to identify the location of a current tunnel is to feel for it with your rig, which will hold easily in slack water, but be pushed downstream by the main current.
Once the water temperature approaches 70ËšF, cats become more interested in spawning. Some fish remain in tailrace areas, but their numbers dwindle as they move toward areas with better spawning habitat. After more than a month of predation, baitfish numbers also have been reduced, and the survivors are warier and more elusive.
Some cats spawn in riprap near the dam, but most move downstream toward slower water with more cover. In the upper Mississippi River, some cats enter backwater areas like oxbows, sloughs, and side channels that contain piles of fallen trees and undercut banks. Other fish spawn in the main river on riprap banks that provide suitable crevices for nesting.
John Pitlo, a research biologist with the Iowa Department of Natural Resources, has been netting cats on the upper Mississippi River for more than a decade to determine the effect of minimum-length regulations for commercially harvested cats. His research has revealed distinct differences in the spawning habitat preferences of flatheads and channel cats.
Before cats begin to spawn, flatheads and channel cats often are caught in the same nets. After spawning commences, though, the range of each species seldom overlaps. Channel cats prefer root wads and logjams strewn along undercut clay banks. Old muskrat and beaver holes are popular spawning sites, too, especially if they're located behind snags or other current breaks.
Flatheads, on the other hand, prefer old riprap walls built during the early 1900s, before the current lock and dam structures were built. The tops of the walls are about four feet beneath the surface at normal water levels, tapering at a 45-degree angle down to 8 to 12 feet of water. Female flatheads lay clutches of eggs in crevices at the base of these walls.
The Spawn Period may last a month or more in some rivers, but Pitlo believes that flatheads and channel cats that are weeks away from spawning are attracted to major spawning sites after the first wave of fish begin to spawn. Prespawn cats probably respond to the pheromones produced by spawning catfish. This attraction is so strong that Pitlo sometimes uses ripe female cats as bait to attract catfish to his hoopnets.
Barge mooring stations, bridge pillars, and other massive concrete structures also attract and hold big river cats. One of the best spots Moyer and I fished during our filming expedition on the Mississippi River was a massive concrete foundation supporting a crane, presumably used to load or unload barges. Current washing against the base of the structure gouged a deep hole on an otherwise featureless flat.
Same's true of bridge pillars, though bridges usually are constructed over hard bottom areas that provide a better foundation. The current isn't able to carve a depression in rock so easily as it does in sand and silt, but the pillars still break the current; and blues, channels, and flatheads often can be caught in the eddy formed behind these structures. The largest pillars create the largest eddies, and often hold the biggest cats.
Not all concrete structures are visible from the surface, though. Old demolished dams are a favorite target for Frank Van Winkle, a veteran catfish angler who plies the Ohio River near Cincinnati. The tops of these structures lie 20 feet or more beneath the surface, but still function as a current break for catfish. Van Winkle says cats, particularly flatheads, spawn in the rocky crevices at the base of the dam and may remain in the area throughout the warmwater season.
Most of the manmade structures on big rivers hold cats sometime during the year. Larger permanent structures usually feature larger scour holes — especially if they're exposed to the main river current — and large holes often hold big cats. Spend more time looking and evaluating options until you get a sense of what's available in a long stretch of river.
Our trip ended successfully, by the way, and the results can be seen on our latest catfish video, Catfish: Predators On The Prowl. During our last night we caught several blue cats to 40 pounds and a flathead that probably weighed 35. Not a bad trip, especially when few local anglers were catching any fish, except for our friend Charlie Thomas, who caught and released a monstrous blue cat that had to weigh 75 pounds, less than 100 yards from where Moyer and I were anchored. "Just goes to show you," Moyer said, smiling, "it's sometimes better to be lucky than good."
Big rivers are dangerous. Turbulence below navigation dams and wing dams are particularly hazardous. If you have any doubt whether anchoring is safe, donÊ¼t anchor. No catfish is worth risking your life.
When fishing the main channel — especially after dark — keep an eye out for barges, too. Like a loaded truck on the highway, tugboats donÊ¼t respond quickly enough to dodge small boats.
Use a quick-release anchor system consisting of a large float on the end of the rope, so you can move fast if necessary. Veteran river anglers also recommend having a sharp knife handy to cut yourself free just in case.