Labor Day weekend was one of the hottest weekends of the summer in the Bemidji area. Then, like someone flipped an invisible switch, fall-like temperatures arrived in the Bemidji area just in time for September.
Surface water temperatures inched their way back above the 70-degree mark again last weekend, which is likely the last time that will happen this summer.
The extended forecast for the Bemidji area is predicting highs in the 60s and lows in the 40s, with the possibility of frost looming on the backside of any cold fronts that pass through the area.
The fall cooldown will almost immediately begin to kill off algae in the lakes, which are very fragile and extremely sensitive to cold temperatures.
Each morning in the fall there will be a thin layer of dead algae on the surface of the lakes. The cooler the night, the more dead algae there will be on the surface of the water.
The dead algae get mixed into the water by the waves and will eventually settle to the bottom of the lake, where they will begin to decompose.
The remains of the dead algae will accumulate on the bottom of the lakes until they rise back to the surface late in the fall, when the lakes turn-over.
The fall cooldown will also have an impact on fish location as the water temperatures begin to drop.
The shallows along the shoreline are the first part of the lakes to cool in the fall.
The young-of-the-year of many species live in the shallows all summer, but they will move out into deeper water as the algae dies and the lake water begins to cool.
Clouds of baitfish will begin to suspend off the sides of structure and anglers can key in on the areas with the most baitfish, where there should be predators taking advantage of the concentration of food in a healthy lake.
Anglers should be able to see the clouds of baitfish on sonar, or they may see the water in the lakes dimpling on the surface as they spook the schools of baitfish as their boat passes over them.
Loons and other diving birds feed on the same things the gamefish are feeding on, which can tip off anglers to the locations of baitfish and the approximate depth anglers should be fishing.
Anglers can find walleyes moving in the opposite directions in the fall, depending on the type of lake.
Shallow lakes without a thermocline will have walleyes moving toward shore, while deep lakes with a thermocline will have walleyes moving toward deeper water as the lakes begin to cool.
Many anglers will make the switch from live baits rigs to jigs and minnows in the fall, partly because leeches are no longer readily available and many anglers only fish night crawlers on multi-hook spinner rigs during the summer.
Most of the natural forage in the lakes is larger in the fall, so anglers can feel comfortable using larger baits for walleyes and other gamefish late in the season.
Anglers need to match the bait with the presentation. Large minnows are more difficult to fish on a jig, unless anglers are using a stinger hook to help catch some of the short hits.
Live baits rigs work well for larger minnows, because anglers can match the size of the hook to the size of the bait and are able to feed the minnows to the fish longer than they could using a jig.
Anglers fishing for pike, muskies and bass can also use larger baits in the fall with good results.
Muskie anglers often switch from spinner baits and surface lures to jerk baits in the fall, to more closely match the large perch, suckers and tulibees the muskies are feeding on late in the season.
Panfish are also active in the fall, with crappies moving into structure and feeding more frequently during the day. Perch will be feeding on flats covered with chara or rocks and bluegills will be feeding on the edges of heavy weed growth.
Paul A. Nelson runs the Bemidji Area Lakes Guide Service. He can be contacted by calling 218-759-2235.