COLUMN: Anticipating spring turnover

Fishing is now in full swing on many lower altitude lakes here in the South Interior

Fishing is now in full swing on many lower altitude lakes here in the South Interior, at least for those anglers who don’t mind sitting out in the cold and rain.

As for myself, I am waiting for a bit better weather. I’m also waiting for a number of my favourite lakes to go through the process of spring turnover.

Normally, spring turnover begins five to eight days after ice-off. This year, however, due to all the rain and cold temperatures, turnovers have been inconsistent.

Spring turnover occurs when the colder water on the surface of a lake starts to mix with warmer waters below. How does this happen? Well, according to what I was able to find out on the Internet, when water temperatures reach approximately 4 C, water molecules become more dense, ultimately sinking to the bottom of the lake and pushing the water it has displaced to the surface.

As temperatures drop to below freezing, surface water forms into ice, effectively capping the lake and preventing further energy loss.

Throughout the winter months, the ice and snow block the sun and photosynthesis ceases. Vegetation on the lake floor begins to die off and decay, giving off heat, which also warms the waters of the lower layer.

In spring, after ice-off, neither water layers will mix until each layer is similar in temperature and then, with a little help from the wind, the layers start to roll over and mix. During this mixing of water layers, the lake tends to become clouded and muddy. Fishing slows right down. Only after the turnover process is completed, will the lake again become rejuvenated with oxygen and the fish start to actively feed.

When both air and water temperatures do begin warming up, it will certainly herald the start chironomids hatches. A successful fly fisher will have a large variety of chironomid patterns in their fly box. The majority of chironomid hatches take place in waters that are no more than 20 feet deep, and although individual chironomids are often tiny, one only has to look at the tremendous number of empty chironomid pupae cases floating on the water to realize just how many are hatching. The pupae stage can be anywhere from less than a quarter of an inch to as large as three quarters of an inch. In shades of pale green to brown, wine and black, chironomid pupae are easily identified by their pronounced segmentation along the abdomen, and the presence of white, feather-like gills on the head and sometimes on the tip of the abdomen.

The pupae emerge from protective tubes in the lake bottom to begin their ascent to the surface by trapping gases under the skin of their abdomen and thorax. Upon reaching the surface, a split forms along the back of the thorax, the winged adult emerges and the mature insect flies off to mate and begin the cycle all over again.

It is during their ascent to the surface that chironomid pupae become easy prey for opportunistic trout which will often feed almost exclusively on the emerging pupae.

Most anglers fish chironomid patterns with a floating line and a long sinking leader.

An integral part of fishing with chironomid patterns is having enough patience to wait for such a tiny fly to sink to the required depth. Strikes are often subtle and hard to recognize. It can take three to five minutes for a fly to sink 20 feet in the water. A slow retrieve is also essential – a couple of inches, pause, a couple more inches, then a longer pause. Too fast a retrieve and your presentation looks too unnatural.

More often than not the trick to post turnover chironomid fishing is to find that one chironomid pattern that the trout just can’t resist. On the other hand, a person can always go see Bill at Westside Stores and ask him which pattern is working best on what lake, like I do.