February 17, 2017
A cold front is a cold front to most folks, but to anglers in the springtime a cold front is a "blasted cold front" that impacts crappie. fishing. That's because the easiest crappie fishing of the year suddenly turns tough when a cold front sweeps through.
Conventional wisdom has it that cold fronts move crappie toward deeper water, making them harder to find and catch. If that's true, how far do they move, how deep do they move, and how long do they stay "moved"? Searching for answers to those questions opens the door to a world where crappie move much more than many anglers realize.
A CRAPPIE WORLD-VIEW
There is a vague but common view that crappie are, for the most part, stay-at-home fish. Their saucer-shaped bodies don't appear to be built for speed nor for long-distance travel. They look like the sort of fish that pretty much live their entire lives in one bay of a large lake, or within a single backwater of a major river. Research by a major university with radio-tagged crappie in large reservoirs in that state, funded by the state fisheries division and through the Sport Fish Restoration Program, suggests otherwise.
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"I was surprised how mobile the radio-tagged fish were in our study," said Dr. Glenn Parsons, professor of biology at the university conducting the study. "Some of them moved the complete length of the reservoirs over a period of only a few days, and they made those movements repeatedly during our study, especially pre-spawn. We assume they were following baitfish, feeding aggressively before the spawn."
Battery life limited the length of the study to late winter through early summer, but during that critical time the radio-tagged crappie moved extensively, not only horizontally but also vertically, especially during the spawn. While researchers assumed the crappie that moved into water shallower than 5 feet once water temperatures warmed to the upper 50-degree range were probably spawning, they could only guess the motivations behind movements to deeper water.
"Some of the fish moved up or down 8, 10 maybe 12 feet and stayed at those different depths for varying amounts of time," said Parsons. "What we don't know is why they made those moves. Was it because the weather had changed and they were looking for a particular temperature of water, or simply because they were chasing baitfish? Whatever the reason, it surprised me how mobile the crappie were, depth-wise."
Once water temperatures climbed into the lower 50s and the spawn began in earnest, tagged crappie in Parsons' study exhibited somewhat predictable behavior. The crappie generically moved into shallow-water bays or arms with hard bottoms, most often with some sort of brushy habitat or flooded vegetation. But they still refused to stay put.
"One fish in particular moved into a creek mouth maybe the length of 10 football fields, turned around and went out like it was leaving, then turned around at the mouth and went way, way up into the creek, and made these major moves several times over a period of three or four days in mid-April, which is spawning time in that reservoir," said Parsons. "It was like it was searching for something — a certain temperature of water, a certain depth, a certain kind of habitat, or maybe a certain combination of all those things. The thing that impressed me was that that fish, and the other fish in our research, didn't just move into spawning areas and stay 'til either the spawn was finished or a weather front moved them out. They seemed to be very mobile, both horizontally and vertically."
Archival radio tags that recorded depths multiple times during the day and night during the research suggested that some of the vertical movement may have been related to sunlight penetration of the lake's water.
"We didn't see it all the time, but we noticed that they'd often move deeper as the sun rose higher in the sky," said Parsons. "They tended to be shallower when it was dark. There was an inverse relationship between light penetration and depth."
DIFFERENCE IS BLACK AND WHITE
The depth frequented by crappie during the spawn was also a factor in a study done by Paul Rister, a district biologist. The research was done to explain changes in catch rates of white and black crappie after systemic changes improved the research lake's water clarity. When the lake's waters were more turbid, white crappie made up the predominant catch. When water clarity improved, the overall crappie harvest declined, and black crappie dominated creel surveys.
"It had traditionally been a white crappie lake with black crappie being less common in creel surveys," said Rister. "It flip-flopped after the clarity improvement."
Subsequent tracking of radio-tagged white and black crappie during their spawn revealed that while both species moved deeper after the passage of cold fronts, the changes in overall catch rates were related to how each species dealt with their "exposure" in shallow water during the spawn.
"There are behavioral differences between white and black crappie," said Rister. "In general, black crappie are comfortable in clearer water. They move shallow sooner, in relation to the spawn, and stay shallow longer after the spawn. White crappie favor water that's a little more turbid, and apparently aren't comfortable in the clearer water that's in the spawning areas now."
Improved water clarity apparently encouraged "spookier" white crappie in the lake to move quickly in and out of shallow-water spawning areas, or to spawn deeper, and so catch rates for whites during the spawn decreased. Because black crappie are more comfortable in clear water, they arrived earlier and lingered longer in shallow spawning areas, and so anglers were able to report increased catches of blacks.
THE TAKE HOME
If we accept that crappie as a species are more horizontally and vertically mobile than expected, and that white crappie behave differently than black crappie, what can we do to improve our fishing prospects during the golden week or two of the spring spawn, even if our region is hammered by cold fronts?
There is no doubt that cold fronts move spawning crappie to deeper water. Consensus is that they slide out to the first significant change in depth. The trick is to find that transition zone.
"After a cold front, don't run in and start fishing as shallow as you caught fish yesterday," said Rister. "If they've moved deeper you'll boat over them and spook them. Start fishing deeper and work your way shallow to find out where they dropped down to."
During the bluebird skies after a cold front, fish deeper. Maybe even do your fishing after dark. Remember the inverse relationship between crappie depth and sunlight intensity.
"They were surprisingly shallow after dark," said Parsons. "Most of our tagged fish moved deeper as the sun rose in the sky."
Because white crappie tend to spawn a little deeper than black crappie (depending on water clarity), movement after a cold front will be toward proportionally deeper water for whites than for blacks. Knowing which species dominates in a lake can allow anglers to adjust their searches for post-cold front crappie.
Considering the surprising mobility of crappie during the spawn, focus on fishing over travel routes associated with spawning areas. Radio-tagged crappie consistently followed creek channels, old roadbeds, and other discrete bottom structure as they moved between shallow and deeper water. Travel routes are choke points that concentrate fish.
Research proves that crappie are much more mobile than suspected, and that some of that movement during the spawn is triggered by changes in water temperature and light penetration related to cold fronts. Or, as crappie anglers call them, those "blasted cold fronts."