PAUL NELSON FISHING: Cooler conditions delay mayfly hatches

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The wind has been consistently strong through most of the fishing season. The wave action from the strong winds keeps mixing the upper layer of the water column and helps the water temperatures in the lakes stay cooler.

Most large walleye lakes still have surface water temperatures in the mid 60s in the mornings, which is the best time of the day to compare water temperatures and track the warming of the lakes.

There were a couple of hot days this week, with more moderate temperatures expected this weekend and then more hot next week.

The cooler conditions help extend the early summer fishing patterns and has been delaying the mayfly hatches. There were some grey colored mayflies starting to hatch last week, so there will be many more on the way soon.

The green tinted mayflies are the largest mayflies in our lakes and they are the last major insect hatch in June. There are more minor insect hatches that continue all summer including many hatches of different varieties of dragonflies.


Dragonflies are experts at catching insects. They like to hang around anglers in boats, using them to attract other insects and to have a place to rest away from shore while they hunt.

Many larger perch have disappeared from the shallows and have headed for deeper water. The perch often hang along the breakline, feeding on insects hatching out of the mud, but also feeding on a variety of forage, similar to their cousins the walleye.

Most walleyes have moved a little deeper, with the majority of them feeding from the outside edge of the cabbage weeds down to about 20 feet.

Each lake is different, anglers need to use their electronics and fish the areas where they are seeing fish on sonar. Once an angler becomes familiar with reading their electronics, it is hard to fish somewhere you are not seeing fish.

The spottail shiners are done spawning and are quickly disappearing from the bait stores. Good jigging minnows are hard to find, with most walleye anglers switching to live bait rigs with leeches, night crawlers or larger chubs.

Anglers can catch perch on fatheads and jigs, but there are usually better choices for walleyes. Fathead minnows work better on lakes where walleyes don’t have large populations of shiners to utilize as forage.

Walleyes react to what is available as natural forage in their home lake. If walleyes have lots of choices, they are usually more picky about what they eat. If walleyes don’t have a lot of choices for food, they will usually be less picky about what they eat.

Leeches and night crawlers are an example of things walleyes like to eat, but they don’t have a lot of either one as natural forage in their lakes.


Some night crawlers wash into the lakes during storms, but most of the nightcrawlers walleyes see are on the end of anglers hooks. Nightcrawlers probably look like a big bug to the fish, but it is the scent and taste that tells walleyes it is something good to eat.

Anglers also use ribbon leeches for bait, which again may be present in the lakes in low numbers, but their natural habitat is freeze out ponds that don’t have predators. Leeches are scavengers and eat dead minnows, frogs and other things that live with them in their ponds.

Ribbon leeches have no need for a protective slime because they don’t have natural predators like larger fish in their ponds.

Horse leeches live in lakes with lots of predators. Their main job is to clean up the things that die in the lakes, along with crayfish. Almost every angler has tried to use a horse leech for bait, but no one I know has ever caught anything on them.

If anglers pick up a horse leech, there is a slime that sticks to your hand that is hard to wash off with just water. Horse leeches have developed a protective slime that causes potential predators to avoid them.

Paul A. Nelson runs the Bemidji Area Lakes Guide Service. Guided trips for 2020 can be booked by calling or texting (218) 760-7751 or by email at

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