Area lakes begin transition from summer to fall
Surface water temperatures in the Bemidji area are getting close to the 70-degree mark, which is the point when fall patterns start to take hold of the lakes.
The change from summer to fall fishing patterns begins gradually and builds steam as water temperatures fall though the 60s.
Walleyes head in two different directions as fall begins, depending on the type of lake.
Shallow lakes don't have a thermocline during the summer because the entire water column is turned-over periodically by strong winds, which keeps water temperatures and oxygen levels more constant from the surface to the bottom of the lake.
Some parts of shallow lakes may get too warm during the hottest part of the summer and the fish will leave the area and head towards the deepest parts of the lake seeking cooler water.
Deep lakes stratify by temperature during the summer, with the thermocline separating the warmer surface water from the colder water on the bottom. Only the warmer surface water is mixed by the wind, so oxygen levels in the lower portions of the lake decline as the summer progresses.
Water below the thermocline in deep lakes may start to run out of oxygen during the summer and the fish are forced into the portion of the lake above the thermocline.
Some large lakes like Leech Lake and Lake of the Woods have elements of both types of lakes, with large shallow bays and deep bays acting as separate parts of the same lake.
When shallow lakes begin to cool in the fall, walleyes and other heat-sensitive species quickly head back into shallow water where they no longer have to avoid the heat.
Walleyes in most deep lakes are limited to staying above the thermocline during the summer and will head towards deeper water when the thermocline starts to disappear as the surface water cools and becomes closer in temperature to water below the thermocline.
Lakes with a good shallow walleye bite in the fall include portions of Leech Lake and Lake of the Woods, Upper Red Lake and Lake Winnibigoshish.
Lakes with a good deep walleye bite in the fall include Bemidji, Cass, Pikes Bay, portions of Leech Lake, Plantagenet and most of the smaller walleye lakes in the Bemidji area.
The transition from summer to fall takes time and the momentum builds as the lake water cools. It is common for the summer patterns to hold for a period of time while the early-fall patterns develop.
Perch also move into the shallows in the fall, with good action in lakes like Winnibigoshish, Cass, Pikes Bay, Bemidji and Leech Lake.
Perch populations cycle through the lakes, with one or two age classes usually representing most of the "keepers" each year. When a lake has a gap between age classes it can take a year or two for the next age class of perch to grow and be of harvestable size.
Leech Lake had a boom of perch, crappies and sunfish several years ago when the walleye numbers were down, similar to what happened in Red Lake in the mid-1990s when the lake produced one huge age class of crappies.
The panfish in Leech Lake have now grown and anglers are taking advantage of the panfish boom by harvesting not only good numbers of big perch, but also increased numbers of large sunfish and crappies.
Walleye anglers in the Bemidji area are still using bottom-bouncers and spinners or trolling crankbaits to locate active walleyes. The best bite is still in the mornings and evenings or when wind or cloud cover breaks up the amount of sunlight entering the lakes.
Walleyes and most other species will begin to feed more aggressively during the day as the water temperatures cool into the 60s.
Most fish struggle to get enough to eat and cope with the heat during the summer but things get easier in the fall and fish have a good opportunity to feed more heavily and put on some fat before winter arrives.
Paul A. Nelson runs the Bemidji Area Lakes Guide Service. He can be e-mailed at firstname.lastname@example.org.