To find big lake trout in late summer, find their preferred food. Here’s how

When the temperature drops almost overnight from a record high—the “feels like” reading was 41° C (105° F)—to a cool 19°C (66°F), you know the fish are going to reactive negatively. But we were determined to catch lake trout, even if we knew they would have their mouths closed tighter than a mouse trap.

September is one of our favourite months to target the big dwellers of the deep and the perfect time to catch (and release) some of the biggest fish in the lake. Diet studies have shown conclusively that up to 85 per cent of the catch in September is comprised of female lake trout that are bulking up, and gaining nourishment to finish off the maturation process of the eggs that they are carrying and will shortly deposit.

I like September for another reason, too. Many lake trout lakes become anoxic and hypoxic in late summer, losing oxygen in the lower reaches as a result of the decomposition that has been occurring in the basin.  This forces the trout—and the trout’s food—to suspend up higher in the water column where oxygen levels are still sufficient.

On our recent Doc Talks Fishing podcast, our good friend, Dr. Chris Therrien highlighted how the biggest lake trout typically fatten up by feeding on soft silvery ciscoes that have a preference for water temperatures around 12°C (54°F).  So the first thing we did when we launched the boat was drop the Fish Hawk thermometer into the water and find where that band of preferred cool water. It was about 48 to 52 feet down, so we highlighted on the Humminbird Helix chartplotter all of the structures—underwater points, reefs, humps and rock piles—that intersected with the ideal band of water temperature. I like to think of it as exposing the lake trout “zone of chaos.” And mayhem is what we enjoyed.

The fishing wasn’t easy as the trout wouldn’t chase, as they typically do, when we pulled our Crush City minnowbaits away from them. We had to hold the baits steady and still, let the trout circle them repeatedly and sometimes even bump them with their noses. But we managed to put a trio of perversely plump lake trout into the boat, and then, back into the lake.

It is too bad you weren’t able to join us, you’d have had a ball, but hop into the boat with us virtually right now and watch how we did it.