September 21, 2017
In many waters, the spring catfish spawning period appears to be a dividing line in catfishing. Prespawn spring catfish fishing can be spectacular, followed by a downturn during and shortly after the spawn, with good fishing again when the fish settle into their summer patterns. What do we know about the catfish spawn behavior that can help explain this seasonal progression? More importantly, what does the biology tell us that will help your catfish pursuits be successful?
The Biological Basics
As so commonly happens when I go to the biological literature to answer "how to catch 'em" or "why" questions, I come up with a few aces and a lot of spaces. The reason: Biologists seek information essential to effectively manage the fish or, in the case of catfish, to spawn and rear them in captivity on fish farms. Thus, from the anglers' perspective, biologists have some answers, but not all. This is certainly the case with the "big three," channels, blues, and flatheads. Indeed, much of what we know about the big three is tied to the important aquaculture industry for channel catfish, so this is where we start.
Feeding Temperatures — Catfish farmers say that catfish feed a little when the water temperature is in the 50°F range, but active feeding doesn't begin until the water hits the mid-60°F range. The success of early spring trotliners suggests wild catfish begin actively feeding at 55°F to 60°F. In northern rivers, where the fish are adapted to a cooler thermal regime, active feeding begins at even cooler temperatures.
Spawning Temperatures — In the wild, channel catfish have been observed spawning at water temperatures of 70°F to 85°F. Some fish culturists consider 80°F to be optimum, but others favor a slightly lower temperature. Based on observations from natural populations, the spawning temperature range appears slightly lower for blues — 70°F to 75°F, and 68°F to 75°F for flatheads. Some anglers disagree with the biologists' observations. Mississippi River guide James "Big Cat" Patterson agrees that the spawning ritual for channels and blues begins at about 70°F. While channels may start spawning at the lower end of the range, Patterson believes the blues don't really begin until the water reaches 80°F. Tennessee River guide Phil King agrees that spawning starts at about 70°F, but King looks for spawning peaks during the full moon in April, May, and June in a warm year, May through July or even August, if water warms slowly during a cool spring. Collectively, the information indicates spawning for blues, channels, and flatheads can be a drawn-out process, but 70°F is a very consistent start of the spawn.
Spawning Behavior — Channels, flatheads, and blues are "cavity spawners." Caverns in banks, hollow logs, washouts under logs or boulders, or deep crevices in riprap banks or logjams are used for their fiercely guarded nests. Aquaculturists sink milk cans, drainpipe, or wooden spawning boxes in the spawning ponds. "Noodlers" (hand-grabbers) are known to add spawning habitat, too.
The spawning ritual involves the male selecting a spawning cavity, then attracting and inducing a female to spawn. The female is then chased from the cavity, and the male tenaciously guards the developing eggs. The eggs hatch in 5 to 10 days, depending on water temperature. Do the males feed while guarding the clutch? They probably don't leave the nest when guarding eggs but, as any noodler can attest, they wrap their jaws around anything that intrudes the nest cavity.
Channel and blue catfish are nomadic. In large systems like the Mississippi or Missouri river, channel catfish migrate out of the tributaries (even when they're as large as the Wisconsin River) to overwinter in deep holes away from current. Springtime finds these fish migrating back upstream, some to the same area they occupied the previous summer. Observations on other rivers — the Buffalo River in Arkansas, the lower Colorado River in California, the Savannah River in Georgia, the Platte River in Nebraska, the Powder River in Wyoming, and the Red River in Manitoba — provide evidence for an upstream spawning migration. The fish move upstream, spawn, and then spend summer back downstream. There is also evidence that channel catfish leave reservoirs in the spring to spawn at upstream sites.
However, not all blue and channel catfish populations are migratory. Researchers found that in Kentucky Lake, the farthest downstream impoundment of the Tennessee River, blues and channels increased movement prior to the spawning season, but recapture provided no evidence for any long-distance migrations to spawning or wintering sites. In lakes, where there is no opportunity for an upstream spawning migration, sexually mature channel catfish have greater daily movement during the spawning season.
No studies have documented whether blue or channel catfish, like salmon, return to the specific site where they hatched (what biologists call the "natal" habitat) or, like walleye, return to spawning sites they used in previous years. The distance and direction blue and channel catfish move is variable among populations in different systems, but increased movement prior to the catfish spawn appears to be a common theme. Possibly, as suggested by the Kentucky researchers, blue and channel catfish move to find suitable spawning habitat. In Kentucky Lake, spawning habitat is abundant throughout the reservoir, so long-distance uni-directional movement may not be necessary. It may also be important to factor in wintering-site migrations. Catfish in warmer climates where water temperature stays in the 40°F range or above may not need deep, slackwater refuges to survive winter.
Do flatheads exhibit similar spawning movements? Several studies of flathead movement in large streams, rivers, and reservoirs indicate these fish are homebodies. They apparently select habitats that provide everything they need for spawning, feeding, and shelter. However, a recent radiotracking study indicates some individuals may be migratory.
Timing the Best Bite
What does the biological information tell us about when the prespawn-postspawn transition occurs? In general, consider 70°F to signal the beginning of spawning, 75°F to 78°F to signal the end. For anglers targeting prespawn cats, it looks like 60°F to 70°F is prime for blues, channels, and flatheads in southern and central U.S. waters. Anglers fishing for channel cats at the northern edge of their range can expect to enjoy good prespawn action when the water is 55°F to 70°F.
When the water temperature reaches 70°F varies across North America. Expect spawning to start in late March to April in the southwestern states and along the Gulf Coast, April to May in southern states, May to June in central states, and as late as July or August at northern latitudes.
These, of course, are generalizations. Nothing beats personal familiarity with seasonal temperature cycles where you fish, but a few general rules may help you forecast the spawn.
If you fish rivers, consider the source of the water. Rivers with flows dominated by snow and ice-melt are slow to warm. In my home state of Mississippi, the Mississippi River water temperatures in March through May are much colder than those in our local streams. In March, the water flowing under the Mississippi River bridge at Memphis may have come from melting snow or ice in Minnesota or West Virginia 10 to 15 days earlier.
On the other hand, rivers with broad floodplains or where flow is detained by dams may warm more quickly. Expect shallow waters to warm faster than deep waters. Temperature cycles, and thus the timing of the spawn, may be stable in natural lakes, with slight year-to-year variation related to air temperature, rainfall, and the number of sunny days. Expect seasonal temperature cycles to be much more variable in reservoirs. Since reservoirs are really impounded rivers, the source of the water and retention time (how fast the water flows through the reservoir) affects warming. Expect water to warm more slowly in reservoirs with short retention time and during rainy spring seasons.
Does the spawn mean the cats won't bite? The biologists' knowledge of spawning doesn't account for a major shut-down in feeding. It appears that not all catfish in any river or lake spawn at the same time; even if they did, only the male is holed up and out of circulation.
Movement patterns may tell you where to look for cats during the prespawn through postspawn part of their annual cycle. Before the spawn, look for upstream movement by blues and channels, especially in cold climates, where the fish may have overwintered in deep slackwater holes in the deeper parent river. A good summer fishing location may be just that — a good place to catch cats in the summer. The fish may not be there during the prespawn or the spawn.
By the same reasoning, a spot where you caught fish in the prespawn may not be where they spawn or where they settle into their summer patterns, if your catfish population tends to make substantial seasonal migrations. The biological information suggests that areas that provide good spawning habitat will concentrate fish when the water is 70°F to 80°F.
Flatheads may be a different story. Although new information suggests that some flatheads move into tributaries during the spawning season, many flatheads appear to remain in a relatively small area.
An Emerging Pattern
It's clear from both the biological information and the collective wisdom of experienced cat anglers that prespawn is a period of greatly increased movement, whether a uni-directional trek away from a wintering area, or a directional or random search for spawning habitat. Couple that with fish restoring energy reserves depleted over the winter and building up energy stores for the ensuing spawn, and that means a lot of active hunters with big appetites.
I have been amazed repeatedly at how effective trotlines are on the lower Mississippi River floodplain during the spring rise. Although common sense suggests fish are hard to catch when they spread out over tens of thousands of acres of water, trotlines fished on the floodplain catch fish; and those fished in chutes, cuts, and ditches can be impressively heavy. While far from a proven fact, the high movement activity during prespawn may have a lot to do with good fishing.
Either way, water temperature determines the start of feeding, the time of increased movement, and the onset of spawning. Temperature is the key to predicting catfish behavior and better catches.
Flatheads on The Move
Studies of flatheads, whether the fish are in streams or large rivers, consistently agree that most individuals confine their activity to reaches less than several miles long. However, a recent study provides evidence that some flathead populations may, like blues and channels, be highly mobile.
University of Missouri researchers radio-tracked adult flatheads in tributaries of the Mississippi (Cuivre River) and Missouri (Grand River) rivers. At 50°F, the fish left overwintering sites for spawning locations; average distance moved during the April to July prespawn period was 12 and 33 miles in the two tributaries. After spawning, some fish remained in the tributaries; others returned to the Mississippi or Missouri. Weekly movement averaged less than a quarter mile per week during August and September. Movement increased again in October when the fish headed for wintering sites.
The flatheads fell into three groups. One group entered the tributaries to spawn and then returned to the big rivers. A second group entered the tributaries to spawn, remained in the tributary during the summer-fall period, then returned to the big rivers to overwinter. The third group moved between wintering, spawning, and summer-fall areas, remaining in the tributary year round.
The Missouri study strongly refutes numerous observations from tag-recapture and radio-tracking studies that indicate adult flatheads move little. Possibly the drastically different movement behaviors of the Grand and Cuivre river fish may be related to the fact that the fish were initially collected in the lower reaches of these tributaries during the prespawn. In other words, the researchers may have unintentionally selected for migratory individuals. Even so, the Missouri study provides powerful evidence for migratory flathead catfish.