Any catfish angler who has spent time on a river knows there are current seams. Most realize these seams are where catfish often move to find bait. Seams are usually located where the shallower shoulder of a river breaks into the main channel. The main channel has most of the water velocity, and the higher area closer to the bank tends to be a little slower. This is the definition of a current seam. Often, all many anglers know about them is that they exist, and that catfish are usually around them.
Where the seams form on this drop-off usually creates an area of little to no current. We often call this a current tunnel. It’s basically a highway for fish moving in rivers during migrations and travel. Once you learn what they look like, how they change the velocity of the current and how they relate to other elements of structure, then you can figure out how fish use them based on different flows and river conditions. With this knowledge, you can be very productive fishing these constantly evolving and changing catfish haunts during the pre-spawn period.
DETERMINE ON VS. OFF CURRENT
The first step is identifying where the main current seam is. Knowing and understanding where that break is should be easy to see on the surface of the water. It looks like a narrow line that boils and runs the edge of the river.
If you are having trouble determining its location, take a look with your depth-finder. You’ll see a fairly dramatic drop-off from the shallower edge to the main channel. This will solidify where the seam is located.
Once you find the seam, start watching the surface of the water and how the seam turns in the river. You’ll see that the current is different on the bank side versus the middle in various areas. You’ll also notice that on an outside bend, the water above the seam to the bank looks to run the same speed as the main current. This is true, as the power of the water is pushing to the bank before it turns the corner. This is why there are typically holes located on outside bends. This is what’s known as “on” current.
If you look at the same corner but to the inside, you’ll see that as the main channel goes by the bend, the water will slow down. In some cases, where it breaks away from the bend, it will form a “V” on the water. The water coming off that “V” is slower running—down to half the speed of the main current. This is called “off” current.
One easy way to see how you are situated in on versus off currents when you are below a river bend is to look upstream from where you plan to anchor in the river. You can normally see the seams and where they are pointing from the bend upstream of your location.
HOW SEAMS RELATE TO STRUCTURE
As catfish anglers, we all know that catfish relate to elements of structure. They use these as current breaks to rest and also to ambush unsuspecting prey that might swim by.
Rivers are not formed in straight lines with perfect seams. They have elements of structure within their normal structure. Examples are rocks, snags, holes and hard-bottom ledges that interrupt the flow of the river along the seams. Some of these might divert the flow of the river over time, while others create a hiccup in the flow.
Usually, looking at the surface you see a boil or flat spot right on the seam you are inspecting. This is an indicator that there is some element under the water. If you have modern electronics, turn on your side imaging and you’ll be able to see exactly what that structure is.
CONDITIONS AND CATFISH MOVEMENT
Channel catfish are much more susceptible to conditional changes such as cold fronts and water-level fluctuation than many anglers think. It only takes a small change in conditions to make catfish move on or off the current seam.
Even a small cold front can change fish patterns, causing them to move from the main current, the on current, to the off side. Barometric pressure from day to day can also inform what is happening. If the barometer is slightly falling, fish should be on current. If it has just bottomed out and is rising, they should be off.
Of course, changing water temperature is also a factor. During pre-spawn, channel cats are looking for warming water. If water temperature is rising, they’ll feed more aggressively. If there’s a front that spurs a couple of cold days, cooling the water, catfish will get sluggish and move off current.
CATCH CATS ON THE SEAMS
It should be noted here that in many cases on- versus off-current bites can be a matter of the side of the boat from which you cast. Fish almost never venture too far from the seam in normal conditions, but they do utilize one side or the other.
Generally, to fish these seams, anchor your boat just on the top side of the seam, cast half of your lines at a 45-degree angle to the on side of the current and allow the baits to settle or even roll back a bit to the seam. Cast the other half of your lines to the off-current side, keeping them on top of the shelf.
Determining which side of the current fish are using shouldn’t take long. Once you’re confident of this determination, anchor on either side of the seam or cast more lines into the most productive seam to increase success. Once a pattern has been established for the day, you can search the river you are fishing for similar areas and often utilize the same part of the seam over and over throughout the day. Fish the pattern rather than spots to stay more consistent.
All of this is to say that there are many things happening along current seams, and even more technicality required for deciphering the seam you want to use. Although it all seems complex, after some time you’ll find this to be a fairly simple and effective way of locating and catching channel catfish in river systems.
A SUREFIRE SETUP
A successful setup for fishing current seams is pretty simple. A medium or medium-heavy rod and a fairly stout reel with about 30-pound line, along with a simple Carolina rig, is perfect. Make sure your snells are not too long. Ten to 15 inches from sinker to hook is sufficient.
The amount of weight you use is critical to success. Flow will determine how much you need to make the rigs stay where you want them—in the strike zone. A no-roll sinker, with its in-line flat design, helps tremendously to keep your bait where you want it. This design also helps prevent snags, as the bait is pulled into place by the current when setting up.
When choosing your sinker weight, it’s best to lean toward the heavy side to ensure the bait stays right where you want it. It is critical to have a heavy enough weight for the off-current side to prevent line drag from carrying the bait into the current. Catfish are typically not afraid of sinkers, as long as they can move it, so a heavier weight than necessary is OK.