Late Ice Transition Time

by Dave Genz with Mark Strand

Dave Genz explains seasonal movements under the ice, as we head from midwinter toward the late ice period

When it comes to any kind of fishing, ice fishing included, we sometimes place too much emphasis on details other than fish location. You can have everything else right on the money… Fish Trap loaded with fresh bait, the right lure, a great rod, Vexilar rigged and ready… but if you don’t have a good idea as to where the fish might be, it’s easy to drill up the wrong tree.

You can drill a hundred holes, but if they’re all in the wrong place, your bait will not be dancing in front of fish.

“It’s important to know about seasonal movements under the ice,” says Dave Genz, the godfather of modern ice fishing. “Those fish don’t just freeze in place down there all winter.”

Indeed. The dynamics that drive seasonal fish movements continue to evolve during the iced-over period, and fish can make significant moves between the time the ice forms and melts away.

“But it isn’t like the same thing happens in every lake,” stresses Genz. “So much depends on water clarity, depth, how long the ice stays, and how much snow there is. So it still comes down to where you have to search until you find where the fish are.”

Knowing that the ‘rules’ aren’t universal, and that you have to search for fish on your own, is a valuable clue. We’ll lay out the rules, which will give you a head start and let you check where the ‘book’ says fish should be.

“But if they’re not there,” says Genz, “that’s when the game really begins. If you’re not catching anything, keep moving until you do. I always say, ‘how long does it take to catch nothing?’”

Late Ice Transition Time

Now, the specifics, the rules, about where fish should be during this time of transition between midwinter and ice-out.

Assuming ice and snow have remained for a month or more, the shallow water is likely to have become low in oxygen, which can cause fish to move into deeper water. This ‘rule’ is fairly well known. What is less known is Genz’s theory on the importance of water temperature. It’s his belief that fish will move away from the coldest water, in favor of warmer depths.

In order to understand this, a quick reminder of what happens to water as it gets colder. You might have learned that water becomes lighter (weighs less) as it gets warmer, and that it becomes denser and heavier as it gets colder. This is true, but only to a certain point.

The interesting thing is that water becomes lighter again when it cools below 39 degrees Fahrenheit. So, in an iced-over lake, the coldest water (just above the freezing point of 32 degrees F) is just below the ice. The warmest water– 39 degrees– is at the bottom.

This dynamic can have a huge impact on fish location. It can explain why there are so many fish in middle depths and in ‘deep holes’ or basin areas, especially at midwinter. It can explain why, even when you have decent-looking, upright weeds or other cover in shallow water, there might not be many fish in the shallows.

This move into deeper water can occur as early as late fall, and in some lakes, an awful lot of fish stay deep all winter long. This, again, is why it’s so hard to make general rules about seasonal fish movements. The specific environmental conditions of each body of water are the real rule makers when it comes to fish movements.

“Still,” says Genz, “these are the general fish movements. They’re very similar to fish movements during the open-water time. In early winter, you tend to find a lot of fish in shallow water. As the winter wears on, you tend to see a lot of fish moving out to midlake spots, away from the shoreline. Then, as we get closer to spring, you tend to see the fish move back into the shallows, because life is returning to the shallow water.”

In a nutshell, those are the general seasonal movements fish make under a coating of ice. And now you see why we are calling this period the transition time leading up to late ice. In many bodies of water, the web of life will return to the shallows, and fish will flow up into shallow water in response to these changes.

Genz has always been on top of this change, and he always starts looking for it as daylength increases and the sun begins to eat away at snow cover, especially around shore. As more sun penetrates back into shallow water, weeds can begin growing again, even under the ice. One little bit at a time, the sun performs its magic, encouraging insect life to come out and play. the shallow water, in many systems, becomes hospitable again.

Eventually, the sun erodes the ice along shore, making it honeycombed, causing it to break free from the bottom in places where it had frozen shut. That lifting force can dislodge plants and insects alike, stirring things up. Long after shoreline ice has become a bit iffy on warm afternoons, the ice farther from shore remains safe to fish, and some of the best fishing of the year is at hand. (As always, wear a life jacket when you go ice fishing, go with at least one friend, and be certain of the ice conditions by checking with a chisel or auger.)

This final phase is actually last ice. By that time, the shallow water can be swarming with fish, some in for spawning runs, others in to eat and breathe the oxygen.

“During the transition between midwinter and late ice,” says Genz, “you have to look for fish to start moving toward the shallow spots. They might still be in deeper water, but they might be staging close to the shallows. That’s why this can be a tricky time, so you have to look, keep moving, drill enough holes to find where they are.”

Indeed. If you don’t find fish deep, look shallower. If you don’t find them shallow, look deeper, especially in places that are close to large south-facing bays, inflowing creeks and rivers, manmade inlets and canals. Be extremely careful around current, as you should always be. But anticipate this transition between midwinter and late ice, and you will have great fishing as the seasons change below you.

Winter Fishing Systems, Inc 2016