When it comes to bass fishing, understanding the variables leads to a productive day on the water.

April is a month of transition in my part of northern Minnesota. Depending on the winter, during early April anglers can fish either on the ice or get their boat on open water.

Many large lakes have major rivers flowing into them that is used by many walleyes to spawn in the spring. The annual spawning migrations bring huge numbers of walleyes into the river systems from the lake and concentrates them where anglers have one of the best opportunities of the year to catch large numbers of big walleyes.

Walleyes migrate long distances to reach the perfect spawning sites.

Lake of the Woods is a huge border lake shared by Minnesota, Ontario and Manitoba.

The Rainy River flows out of Rainy Lake and runs for about 85 miles before it enters the Lake of the Woods, with many miles of shoreline on both sides of the river that are perfect spawning habitat for walleyes. Walleyes from all over Big Traverse Bay of Lake of the Woods migrate toward Pine Island late in the winter and stage at the mouth of the Rainy River until something triggers them to enter the river and spawn.

Anglers from all over Minnesota and neighboring states make their own migrations to the Rainy River in the spring, to participate in the spring walleye season that runs from March 1 to April 15. The Rainy River is still usually ice-bound on March 1, so the season actually begins as soon as anglers can get their boats in the river and that date varies from year to year.

The spring walleye limit is reduced to two walleyes under 19 1/2 inches, to protect the large female walleyes at this critical point of the year.

The spawning migration into the Rainy River begins before the ice leaves Lake of the Woods. At some point in March, you can usually find anglers ice fishing on Lake of the Woods while other anglers are putting their boats in the Rainy River to fish open water.

It is hard to beat the excitement of doing anything for the first time, whether it is getting out on the ice in early December or getting into a boat for that first day you can fish open water on the Rainy River.

I have fished this spring walleye season for much of my adult life, so it always brings back memories of good spots and big fish I’ve caught in the past.

I like to stay closer to the lake in the spring to fish for walleyes, but I have fished the entire Rainy River all the way to the dam at Rainy Lake in the past. (Incidentally, the upriver sections are good for smallmouth bass most of the summer.)

I have a mental picture of the entire Rainy River in my mind after many years of fishing it. The Rainy is an International Border Water, so Canada controls the north half of the river and the USA controls the south half. I can see the border on my Humminbird Helix 12 when I use the Lake of the Woods LakeMaster Mapchip, which is much more accurate than trying to estimate where you are in relation to the border with your eyes alone.

Anglers from both countries have to stay on their own side of the Rainy River, but each side has plenty of good spots to fish and the entire river is full of walleyes in the spring.

A spawning run of lake sturgeon into the Rainy River also happens in the spring. Walleye anglers catch plenty of sturgeon incidentally. Other anglers successfully target these sturgeon during the spring catch-and-release season.

The new G2 technology on the Humminbird Helix units gives anglers an unbelievable edge when fishing in rivers using the Mega side-imaging technology. The walleyes and sturgeon can’t hide. Anglers can search their half of the river with crystal clear images that show the actual fish migrating along the bottom and holding in the current breaks.

Once I have located the right school of fish, I position my boat slightly ahead of the fish and deploy my bow-mount trolling motor.

Want to learn more spring fishing techniques? Look for the full article in the April issue of MidWest Outdoors, available the first week of April at the newsstand or by subscribing on our website.