Keeping Pace During Early Season

By the time spring has come and gone, flatheads have transformed from a phase of almost complete inactivity to becoming metabolic superheroes. The changeover isn’t as quick as Clark Kent in a phone booth; it happens with environmental conditions shifting through the season at nature’s pace. Still, there’s a lot happening in a relatively short time, making this the most unsettled season for flatheads. It also starts out slow and often frustrating for anglers, but ends with some of the best fishing of the year.

Flatheads pass through several phases from late winter through the Spring Coldwater Period on to Prespawn. During early phases in particular, they almost seemingly disappear before showing up for a good prespawn bite. But along the way, they’re just living the life, responding to environmental cues that push their biological buttons for survival and reproduction. Along with that are physiological and behavioral responses that dictate where they are, what they’re doing, how aggressively they’re feeding, and where they’re going. Sounds simple enough. Know what cues them and make predictions about location and presentation.

But even the best fishery science available and our catfishing experiences don’t give us a formula that tells us all there is to know. There are just too many variables and processes happening. And, no two rivers are exactly alike. Even in a single water, conditions can be quite different from one spring to the next.

But what we do know today is making early-season flatheading more like a fair game of hide and seek than a magic act. Discoveries from scientific studies and experiences of top anglers are developing into something like an unfinished roadmap, but with no single road showing a guaranteed connection between you and flathead town, though one route in particular—water temperature—looks like a good one to follow.

Cold-Blooded Control

Temperature is a life-controlling factor for cold-blooded animals like the flathead catfish. Temperature regulates metabolism—physiological processes—and affects behavior such as activity and feeding. Metabolism slows in cold water and speeds up in warm water. Temperature alone doesn’t tell us everything about what flatheads are doing, but it offers some basic clues to various stages of behavior that flatheads cycle through during the early season.

To follow the thought process through, step back to winter, when flatheads are experiencing the coldest water of the year. In more northerly areas of their range, flatheads congregate in wintering sites. These spots tend to be deeper holes, although they’re not always the deepest holes in a river stretch. Good holes feature rough bottoms with larger rocks or wood, which serve to reduce flow near bottom and provide current refuge for cold cats. In a long river stretch with several dozen possible wintering spots, there might be only a few holes that have the features to attract the bulk of the population.

This was the case in a Minnesota DNR study on the Minnesota River. Biologists sampling flatheads from river pools in December reported that flatheads wintered in select holes. Some of the sampled fish had sediment deposits on their dorsal surfaces, suggesting that they remained still enough on bottom for silt to settle on them. In a different tagging study in the St. Joseph River in Michigan, flatheads also didn’t move while they were at wintering sites. Whether the overwintering-hole scenario plays out in far southern waters isn’t known, but another tracking study showed it to be the case in rivers as far south as Missouri.