Summer is big-fish season—but only if you fish deep enough. Here’s why

You don’t hear it as often these days, as you did in the past —more modern excuses have taken its place— but it’s still opined by plenty of anglers who have miserable days out on the water.  It is the old wives tale that the fish lose their teeth in the middle of summer and that their resulting sore mouths cause them not to eat.  Of course, it is as ridiculous an excuse today as it ever was in the past.

We were enjoying a good chuckle about this nonsensical fabrication on our recent Doc Talks Fishing podcast with Dr. Christian Therrien, because Chris has sampled some humongous lake trout, smallmouth bass, walleye and pike up to 50-inches in length while using test nets.  And when he has analyzed their stomach contents they’ve been full and satisfied. So why the gnashing of teeth —sorry, I couldn’t resist the pun— about sore jaws and lethargic fish?

It is because the grumblers are typically fishing in areas of the lake where the water is too shallow and warm, and not out in deeper cooler sections where soft, silvery, oily, nutritious and delicious ciscoes are attracting the prodigious predators.  Indeed, as Chris explained in the podcast, when you find the ciscoes —also known as lake herring and tubliees— you find the biggest walleyes, bass, northern pike, muskies and trout.

“We have models that can predict where they’re going to be with incredible precision,” he says. “So why cisco move the way they do and where they occupy the way to do is a balance of water temperature, food, predation risk and environmental factors.”

Undoubtedly one of those last key considerations is finding where the water temperature that cisco find most agreeable —between 10°C and 15°C or 55°F and 60°F —  converges, connects and intersects with the structures where the top predators are lounging.

“I look for the structure that might hold some of the cisco’s prey,” says Therrien.  “They really like to feed on mysis shrimp.  Mysis like to hang out near the bottom and they’ll come up in the evenings and feed on the accumulated plankton and then head back down. So if you can find a bottom overlap —a main lake hump, a shoreline— that intersects with the thermocline, that’s a good area.”

Therrien says pinch points and wind swept areas producing oxygen also fuel the productivity of the system. So he looks for breezy points and areas of current that move plankton and carbon throughout the system. And when he finds a spot where the ciscoes flourish and thrive, the giant lake trout, walleye, smallmouth bass, northern pike and muskies are never far away.

The listen to the entire podcast with Dr. Christian Therrien, who specializes in studying the habits and habitat of ciscoes, tune into the latest episode of our Doc Talks Fishing podcast on your favourite podcast provider, or click on the link below.