Late summer and early fall see a sweet pattern for super-size walleyes and northern pike on lakes across the Upper Midwest. It hinges on the thermocline, and it can produce big fish all the way up to fall turnover.
Longtime guide and NAF friend Scott Glorvigen tipped me off to the fact the program is on fire right now on north-central Minnesota’s lakes Winnibigoshish and Cutfoot Sioux. While fishing a tournament with his son, he stumbled into the mother lode of big pike, catching numerous fish over 10 pounds, with a number in the high teens and two true gators topping 20 pounds. And yes, hungry ’eyes were smiling, too, as they boated fish up to 28 inches in the process.
The key was finding an area where low levels of dissolved oxygen forced baitfish out of the cool, deep hypolimnion into the metalimnion, or middle layer of a stratified water column. Home of the thermocline, this slice of paradise is worth seeking out on lakes that stratify by temperature.
Predators and baitfish may roam anywhere the metalimnion sets up, but places where it hits classic structure such as offshore reefs set the stage for epic feeding binges and great fishing. Glorvigen uses his Lowrance HDS sonar to pinpoint the hot zone. It’s usually easy to spot, since a thin layer of suspended particles often rests atop the hypolimnion underneath it. If you don’t see it right away, he suggests adjusting sonar sensitivity until a slight band appears. You can also gauge its location by noting the depth and which you stop marking fish.
Once he finds the fish-rich middle ground, Glorvigen typically focuses on a 10-foot section of the column just above the thermocline. Crankbaits take fish suspended in open water, but on structure, big minnows on live-bait rigs get the nod. Glorvigen’s go-to setup consists of a 7-foot medium-action spinning outfit spooled with 10-pound-test superbraid such as steel-gray Northland Bionic Walleye Braid or Berkley FireLine Crystal, tipped with a 6- to 7-foot leader of Berkley Professional Grade Fluorocarbon in the 8- to 10-pound range.
Fluoro is abrasion-resistant enough to handle most pike, while the braid’s sensitivity is critical to monitoring the minnow’s behavior, he explains. When the minnow gets excited, you know a big predator is lurking in the neighborhood. Often, letting the minnow run on slack line will trigger a strike, and thin-diameter braid is also easier for the minnow to pull through the water.
He typically rigs a 6- to 9-inch or larger creek chub or redtail chub on a size 1 or 2 upturned red hook. Light lip-hooking keeps the bait lively and struggling, though at times, predators show a preference for baits hooked in the corner of the mouth. If cold fronts and light biters dictate a stinger hook, he adds a No. 12 to No. 16 treble near the dorsal fin, but he cautions that the extra steel may impede the minnow’s movements.
In clear water, speeds of .7 to .8 mph are ideal. Dark water calls for a slower pace, to give predators time to find the bait. In either case, when a pike or walleye grabs the minnow, Glorvigen gives it room to run. He keeps his bail open and trigger finger on the line, so it’s a simple matter to strip line off the spool. Let the line coil on the surface and watch the coils. As soon as they start straightening out, raise your rodtip while reeling fast. When you feel the weight of the fish, set the hook.
Such maneuvers typically result in firm hookups without full-scale swallowing, and are a perfect way to enjoy great fishing until fall’s cooling water temperatures wash away the thermocline in late September or early October.