Fish are searching for new food sources
The weather turned hot in the Bemidji area as soon as the calendar turned to July. July is typically the hottest month of the year and July 2010 seems to be following that historical weather pattern.
Surface water temperatures in most lakes spiked into the mid-70s this past week. The sudden increase in water temperature finished off the mayfly hatches and is quickly increasing the algae bloom in many lakes.
The end of the mayfly hatch breaks up the food chain that had been active in deep water for more than a month. This forces both predators and baitfish to search for new feeding opportunities in other parts of the lake.
Fish are fully dispersed into much of the basin of the lakes during the mayfly hatch. Once the thermocline begins to set up in the deep lakes and the algae blooms begin to reduce the water clarity in the lakes, the number of usable acres in the lakes begins to shrink again.
Shallow lakes act differently than deep lakes in the summer.
Shallow lakes like Winnibigoshish, the main basin of Leech Lake, Big Traverse Bay of Lake of the Woods and Upper Red Lake are large enough and shallow enough that strong winds periodically turn over the water column, which breaks up any temperature stratification in the water and evens out the oxygen content from the surface to the bottom of the lake.
Walleyes and other species of fish are able to use all depths in the shallow lakes during the summer, while fish in deep lakes have to deal with a thermocline.
The thermocline is a narrow, but distinct point in the water column where water temperatures make their most drastic temperature change.
The thermocline sets up a barrier in the water column, where the water above and below the thermocline stops mixing.
Fish in deep lakes with a thermocline may go below the thermocline as long as they can find enough food to eat and the oxygen levels are in the tolerable range.
During extended periods of hot weather, oxygen levels below the thermocline may drop too low to support fish, which forces the cold water species into the warmer water above the thermocline to find suitable oxygen levels.
Anglers should expect many fish species to be changing locations. The general progression of most fish species in lakes with a thermocline is towards structure and shallower water.
Walleye action has slowed in most lakes, especially during hot days with little wind. The days are still very long and there is no reason for walleyes and other species to feed when the conditions are not in their favor.
Anglers may be able to coax a few fish to bite during non-peak feeding periods, but the best walleye action has been in the mornings and evenings or after dark on many lakes.
Many anglers have started using spinners for walleyes, which adds vibration and flash to their presentation to help walleyes target their baits more effectively.
Spinners also add lift to anglers' baits, making it harder to keep baits close to the bottom. Most anglers can use a 1 ½ or 2-ounce bottom bouncer with their spinner rigs to keep them close to the bottom at higher speeds.
A two-hook spinner rig works best with night crawlers. Anglers can snip off the tail of the night crawler close to the back hook, to force the walleyes to strike at the hooks. Singl-hook spinner rigs work better for leeches or minnows.
Anglers usually "feed" line to walleyes on a live-bait rig, but anglers fishing bottom bouncers and spinners should set the hook immediately when they get a bite. Anglers having trouble setting the hook may want to put the rod in a rod holder and let the fish set the hook themselves.
Anglers wanting to stay on active fish all day should consider fishing walleyes during the mornings and evenings and switch species like perch, northern pike, sunfish or bass when the conditions are too bright and sunny for a good walleye bite.
Paul A. Nelson runs the Bemidji Area Lakes Guide Service. He can be e-mailed at firstname.lastname@example.org.