RED WING, MINN. – The "Judge" didn't make an appearance in our boat until 10:30 a.m., and it ruled against us on our first walleye of Opening Day.

Afloat on a narrow channel of the Upper Mississippi River about a quarter-mile south of Colvill Park, the bite was next to zero for the first four hours. Fellow anglers acknowledged as much as we all maneuvered around buoys, deadheads and sandbars on a bend in the Mighty Miss below lush, wooded bluffs.

"At least we can enjoy the scenery," one of the passing anglers said. "It'll pick up."

Within the half-hour, it surely did. Scott Ward, my lifelong friend from West St. Paul, converted the first bite of the day into a catch. Wishful thinking told us it just might be big enough to keep, but the "Judge" — our trusty steel measuring stick — adjudicated the fish at just under 15 inches, the minimum length for keepers along the border with Wisconsin.

"Well, at least we're on the board," Scott said.

Over the next 15 minutes, boats around us hauled in three more walleyes and a big bass. One of the walleyes was 19 inches, raising a few shouts and adding to what was a sunny, festive vibe on the river. At nearly any point in time throughout the morning, you could see 12 to 15 boats within close proximity.

Red-winged blackbirds and a loud rose-breasted grosbeak trilled and whistled from a nearby tree-covered island early in the day. By 11:30, the boat traffic included big cruisers weaving around clusters of fishing boats. Most anglers, including us, trolled slowly with live bait rigs or crankbaits.

Others (also including us), lowered heavy jigs for repeated short-range drifts down stretches of 12- to 15-foot water near shore.

Lake Pepin and the rest of Pool 4 along the Mississippi has long been a popular fishing destination, but fisheries biologists for the Minnesota Department of Natural Resources have been talking about a surge in perch, walleye and sauger populations. The boom has resulted from consecutive years of high water during the spawning season. Walleye counts in particular have been at near-record highs.

While many of the new fish are still too young to keep, they generally grow up faster than walleyes that swim in most northern Minnesota lakes. Growth rates are rapid in Pool 4 because of an abundance of forage. Nick Schlesser, DNR large lake specialist based in Lake City, said walleyes that measure just under 15 inches this weekend were likely born just two years ago.

The 2019 year class is one of several strong years classes of walleye and perch now coming of age in the area, he said.

Pepin also is home to a sizable sauger population and DNR's 2020 survey nets captured an average of about 30 sauger and walleye combined. Those fish already have grown to about seven to 10 inches long.

In truth, Pool 4 — with its Wisconsin border water designation — is open continuously for walleye fishing with a bag limit of four fish (walleyes and saugers combined) larger than 15 inches, only one over 20 inches. Saturday was Opening Day in spirit.

Schlesser's advice for May walleye anglers in Pool 4 is to fish the main channel border waters upstream of Lake Pepin's head. The fish should start showing up in the upper portion of the lake as the water warms, he said.

And if the walleye aren't biting, he said, anglers at this time can expect the drum, or sheepshead, to provide dependable action.