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Paul Nelson: Water levels, temperatures continue to rise on area lakes

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outdoors Bemidji,Minnesota 56619
Paul Nelson: Water levels, temperatures continue to rise on area lakes
Bemidji Minnesota P.O. Box 455 56619

Lakes and rivers in the Bemidji area continued their fast rise, both in water levels and in surface water temperatures.

Surface water temperatures determine much of what happens in the lakes. The timing of the changes that happen over the course of the summer are also largely determined by water temperature.


Most species of fish in the lakes spawn in the spring, with tulibees and whitefish the notable fall spawning exceptions.

Water temperatures choreograph when each species spawns, with the timing and the location where each species of fish spawns all part of an elaborate, highly organized symphony.

If there could be time-elapsed videos to document the comings and goings of each species as they spawn, anglers would be amazed at how connected everything is and how complex the timing has to be to give every species in the lake a time and place to spawn.

The males typically come in first and leave last, so there are fertile males ready whenever the groups of female fish move in to spawn.

Anglers may notice when they fish for crappies in the spring that most of the fish will be the dark colored males. Occasionally, however,  a school of lighter colored females will move into the area, usually during peak feeding conditions. This trait is typical of most species of fish.

The dark color on the male crappies and the light colors on the female crappies are most pronounced in the spring because of the spawn.

It is still possible to tell the difference between male and female black crappies the rest of the year as the colors fade, but it is not as easy as it is during the spawn.

Surface water temperatures in most lakes in the Bemidji area are in the upper 60s. Most lakes should break through the 70-degree mark soon, which is the point when summer fishing patterns start to develop.

Bass, crappies, sunfish and muskies are among the last species to spawn each spring. The next big thing in the lakes after the fish spawn is the insect hatches out of the mud basins in the lakes.

The shift from shallow spawning fish to deep hatching insects helps spread the fish as they disperse into the lakes.

At the end of the aquatic insects’ one to three-year life cycle, they emerge out of the mud, rise to the surface of the lake, molt and turn into flying insects to complete their life cycle.

One of the first insects to hatch out of the mud are midges, which look like mosquitoes without stingers. They also are known as blood worms in the larval stage.

There are also several species of mayflies and dozens of dragonfly species that hatch out of the lakes. Some species have such a short life as insects they don’t even have mouths to feed. They just mate, lay their eggs back into the lakes and die within a few days of molting.

Other species, including dragonflies, have a longer life as winged insects. They are insect eating machines and often hover around anglers’ boats, picking off the smaller insects drawn to the boat by the humans inside.

Muskie season opens on Saturday. Anglers will probably see more male muskies early in the season, but somebody usually finds an active female with all of the fishing pressure on the opener.

There is a DNR proposal in the works to increase the muskie size limit to 54 inches, with a 48-inch size limit on hybrid muskies. A hybrid muskie is a cross between a female muskie and a male northern pike.

Another change likely to be implemented is the opening of trout lakes in Becker, Beltrami, Cass, Crow Wing and Hubbard counties to winter trout fishing. The trout lakes in those counties have been closed in previous winters.

Anglers can get more information on these and other proposed changes at the DNR website or make comments by contacting The deadline for comments is 4:30 pm on July 18.

PAUL A. NELSON runs the Bemidji Area Lakes Guide Service. He can be contacted at