Air temperature can be a guide to human behavior. As temperatures fall in autumn and early winter, outdoor activity slows dramatically. If outdoor activity ceased altogether, one might say air temperature was a controlling factor in behavior.

It’s not. It’s simply a guideline that points out how most people respond to conditions. Some, for instance, spend more time outdoors in winter than in summer, highlighting individual differences and preferences.

The same is true with fish. Water temperature is a guide that helps us understand how most fish react most of the time, but it’s not an absolute controlling factor. Take panfish in spring. When the ice breaks up in northern states, the water temperature can be as high as 50°F in shallow, dark-bottomed bays with lots of sun exposure. Many of the panfish in any given body of water will be there, feeding—but not all of them. Some stay deeper longer in spring. Those fish tend to spawn later on main-lake spots.

Using temperature as a guide is wise, but thinking of it as a determining factor in fish behavior can be misleading, even when it always seems to work. Fish may move out of so-called comfort zones and stay out. One bluegill may react differently than another to the same temperatures. But we can predict what most panfish do most of the time by using temperature as a guide. So consider the following as general guidelines, not a list of edicts.

Differences North & South

Temperature profile is one of the main differences between northern and southern panfish location in spring. In Minnesota, a shallow bay with good sun exposure generally freezes in November and won’t reach 50°F again until late April or early May. In Florida, a shallow bay on a good panfish lake might never get cooler than 50°F all winter. In Minnesota, when the water hits 50°F in spring, the panfish throw a big party and eat themselves sick. When the temperature drops to 50°F on a Florida lake, the panfish might shut their mouths and refuse to eat again for days.

That’s a drastic contrast, but consider this: Traveling 50 miles north or south usually crosses a substantial climate line anywhere between Canada and Alabama. The panfish in lakes just north of you might shut down during a cold front that hardly affects the lakes near you. The fish of every lake carry with them the genetic reactions to the weather of their own micro environments over tens of thousands of years. That lake 50 miles north? The panfish in it might look the same as those outside your door, but they might react differently to similar conditions. A lake is like a library, each with its own unique genetic lineage.

Micro climates exist that consistently make certain areas on a lake colder than other areas of the same lake—springs, shade, depth, current, and water clarity. Panfish living in an area that’s colder don’t necessarily leave to find warmer water. Forage can become an overriding factor. The fish that do leave deep water to find warmer, shallower water probably aren’t triggered by temperature at all. Panfish sometimes move from water that has been a consistent 39°F for months. The trigger could be length of daylight. Increased sunlight penetration through the degrading ice? Ennui? We don’t always know precisely what triggers panfish to move from winter to spring habitats.

If water temperatures have been under 50°F for a time, that particular point on the thermometer becomes important. As waters broach that temperature, panfish turn on. It’s a good time to be on the water. In Tennessee, where water temperatures typically hover in the low-40°F range all winter, 50°F water temperatures might first occur in early or mid-March. But even shallow bays in Wisconsin or New York might not reach 50°F until May.

Early Spring Movements

When the ice goes off northern lakes, some panfish may have been shallow for weeks or months. Water temperature in the main lake typically is around 40°F the day after the ice breaks up. During winter, panfish in northern natural lakes tend to spend most of the winter deep, on 20- to 40-foot flats. In many lakes, panfish arrive in shallow spots during last-ice (late March, early April). Ice fishing late in the season can produce big crappies and bluegills in reedbeds no deeper than 5 feet in some lakes. But in others, panfish won’t arrive until ice leaves the shallows altogether.

If the main lake is 41°F at ice-out, shallow bays can sometimes register as high as 48°F to 52°F, especially after a few days of sunlight. Dave Genz, longtime contributor to In-Fisherman on panfish subjects, follows the sun in spring. “The biggest panfish move shallow first, usually during the first calm, sunny days after ice-out,” he says. “It’s always a big-fish pattern. Sunny days warm the shallow bays, and the lake’s biggest panfish tend to be the first to arrive. Even when ice still covers the main lake, the biggest fish arrive first in bays that have thawed. I’m not a big temperature-gauge guy, but calm, sunny days in early spring are my cues to hit the water. Several days like that always precipitate hot panfish bites in early spring. The first places to check for bluegills, crappies, and perch are bays with wood like stumps, fallen trees, and brush, which seem to absorb additional solar energy. A creek flowing in, bringing warmer water, is another good sign.”

Thermal zones that warm quickest in spring are prime attractions at most latitudes. In states where lakes never ice up, 50°F is still a key temperature. Bob Holmes, an accomplished bluegill guide in Tennessee, says, “...50°F is like an awakening. The water’s been colder than that for months, and it triggers a major feeding spell.”

Holmes spends most of his guiding days on Reelfoot, a natural lake formed by an ancient earthquake. It’s a large but relatively shallow lake, with some holes approaching 20 feet. “Some crappies use those deep areas in winter, but others use shallow, dark-bottom bays, and flats thick with timber. Maximum depth is about 3.5 feet. The dark bottom and wood absorb solar energy, and we can sometimes catch crappies all day, every day, in areas like this during January and February.”

Northern crappies rarely occupy such shallow areas during winter, except in flowages, backwaters, and other riverine environments.

When surface temperatures hit 50°F in shallow bays and coves, especially when temperatures have been colder than that for some time, magic happens in the panfish world. The fish bite like they’ve been starved for weeks, which, in fact, they have been, in some cases. Some panfish remain deep or suspended in the main lake or in the back third of major creek arms in reservoirs in the South, but they tend to bite well. In the North, the most active panfish are shallow at 50°F, using coves and shallow south-facing bays with brushy shorelines.

Since at this point, bluegills and crappies won’t spawn for a month or six weeks, the main attraction could be forage density, as opposed to warmer water. Several species of panfish might occupy the same bays or spots, because small minnows concentrate in these shallow bays, too, and the warming water encourages insect hatches in shallow, soft-bottom areas. It doesn’t have to be a cove or bay; big shallow flats draw them, too, when water temperatures broach 50°F.

When conditions dip back below 50°F during the day due to a cold front, the bite changes dramatically. Bluegills may move out to the base of drop-offs outside these bays, while crappies move back over open water and suspend, in a complete reversal of the shallow migration.

In states like Arkansas, Tennessee, and North Carolina, reservoir crappies in winter tend to congregate near the intersection of the main river channel and a creek channel. They occupy the front third of major creek arms, suspending over 30- to 50-foot depths or holding on breaklines in that range from November through early March. Fishing can be good at this time. “Crappies start moving out of those wintering holes at about 50°F,” according to In-Fisherman co-founder, Al Lindner. “The first thing they do is rise. Straight up. They suspend for a short time, then begin moving toward the creek arm. Not all of them go at once. Little pods of crappies rise and slowly begin to migrate, 10 to 20 feet under the surface. Later another pod follows, so fish are spread out over a large area.

“Crappies stay or stop where they’re at during bad weather,” he says. “They gather for a time and stage at the creek mouth at the head of the creek arm. Huge concentrations sometimes occur, suspended over the area around the intersection of the creek arm and the main river channel. Then they spread out and migrate to the back third of creek arms, as water temperatures approach 60°F. At 60°F, most crappies begin making the transition to shallow brushpiles and wood along shorelines where they later spawn, when water temperatures reach the high 60°F to 70°F range.” Of course, some crappies spawn later on main-reservoir shorelines, because it takes longer for that bigger, deeper body of water to warm.

In northern lakes, much the same happens at all key temperature points Lindner mentions. At about 50°F, large groups of bluegills and crappies gather in shallow bays, though some stay deep in the main lake (Mother Nature putting eggs in various baskets). This is not a spawning movement or “staging” in the classic sense. It’s a foraging movement. Somewhere above 60°F, actual staging begins, and often, many panfish leave the areas they inhabit at ice-out, moving toward traditional spawning areas. Bluegills seek out sandy shorelines and old lily-pad beds, while crappies head for reedbeds or emerging weeds. Both species begin spawning in water temperatures approaching 70°F.

At any given juncture during these spring migrations at any given latitude, cold fronts and falling water temperatures slow the progression or even reverse the migration pattern. In Canada or Arkansas, or any point in between, panfish often retreat from shallow spots into deeper water after a severe cold front.