Line placement, lure presentation, and boat control are absolutely critical for early-season shallow-trolling success in lakes for trout. Shallow fish are easily spooked, however. You can't just motor through the shallows and expect fish to stay around or to be receptive to the offering you trail behind.
Fishing for shallow trout in lakes early in the season is a challenge because the water is undergoing dramatic changes and because trout can be almost anywhere.
To be successful, you should cover a lot of territory and be versatile.
Make Creative Presentations
The simplest method of shallow-trolling is to run a flatline straight out behind the boat. But whether you flatline or not, remember that the clearer the water, the shallower and spookier the fish, and the more local boat activity there is, the longer the line you need.
Trout in shallow water will move out of an oncoming boat's path. That is one reason why you seldom see trout in less than 15 feet of water on sonar. Proper boat maneuvering can bring lures into the range of fish that are out of the boat's path, so regularly alter the lure's path of travel by turning, steering in an S-shaped pattern or in other irregular ways, or by changing the speed of the boat. It is also a good tactic to sweep in and out from shore, and to plan strategic approaches to points, sandbars, islands, shoals, channels, and the like.
Start As Soon As the Ice Melts
You can begin fishing as soon as the ice goes out.
On inland lakes, I've found that good fishing occurs for several days immediately after ice-out. Success then drops for a short while until the water stratifies; then fish seek out the warmer surface water and angling success increases. A warm rain and brisk winds can make ice disappear overnight, so it's a good idea to keep an eye on conditions and to get on the water at the first opportunity.
One spring Saturday, I fished an inland lake that was mostly covered with thin ice. A warm front came through that night followed by a day of heavy rain, and the ice melted. Monday afternoon a friend and I spent an hour bypassing a washed-out road to reach the lake, but four hours of fishing yielded one 12-pound and two 5-pound brown trout. We came back the following day and caught four more, the best of which topped 10 pounds. Fishing was hot for a week, then slacked off temporarily. During that week, though, almost no one else was lake fishing, and they missed the fastest action.
Watch the Temperature
Generally, especially on inland lakes, the most dependable angling doesn't begin until the surface water temperature reaches the mid-40s. Many inland trout lakes are relatively small, a fraction of the size of the most prominent trout and salmon waters or any of the Great Lakes. Some are natural, some are manmade and used for water supply or hydroelectric purposes. They are all good two-story lakes, having respectable warmwater fish populations as well as brown and lake trout and/or landlocked salmon. They all have coldwater environs, with the greatest depths ranging from 70 to 120 feet.
In the early spring, there are concentrations of fish in 50 or more feet of water, often near the dams of the impoundments and over the main channels. But the deep-water temperature at that time is only several degrees above freezing, while the surface temperature is 8 to 12 degrees above freezing.
Concentrate on the upper layers of the lake. Trout individually move out of the deep levels to be in the more comfortable upper layer and to search for food. These fish are hungry and can be caught.