David Nasby of St. Paul fishes the St. Croix River because it’s nearby and because it’s flush with fish. And surprises.

May 1, the Sunday of the first weekend of border-water fishing on the big river, Nasby was on the St. Croix with a cousin, Kevin Birch of Champlin.

Looking for walleyes, Nasby and Birch were trolling in about 14 feet of water on the Wisconsin side about a quarter-mile south of the mouth of the Kinnickinnic River.

The water temperature was 50 degrees.

“That’s when it hit,” Nasby said. “I thought it was a good smallmouth.”

But the fish wasn’t a bass — or any warm-water species, for that matter. Instead, Nasby and Birch had hooked a brown trout measuring 25 inches long. The fish hit a white No. 5 Flicker Shad.

“Well, the Kinnickinnic has trout, so I suppose it came from there,” Nasby said.

Six days later, Nasby was back on the St. Croix, this time with his son-in-law, Manny Gomez. The two were trolling for walleyes, again with Flicker Shads, including the No. 5 that had fooled the brown trout.

“We were in about 14 feet of water and trolled over a 9-foot hump where I had caught a big walleye last summer,” Nasby said. “As the lures dropped off the hump, one of our rods just bent over.”

The struggle that ensued was endless. Or so it seemed. Finally, a half-hour later, a garage-sized flathead catfish appeared near the surface.

“I don’t know how old that fish was — 30, 40, 50 years, whatever — but I don’t think it had ever seen daylight before, because once it neared the surface, it dove again for another 20 minutes,” Nasby said.

The trout and the big cat are only two of an all-star lineup Nasby has caught in the St. Croix this spring. Other fish he has tricked include smallmouth bass, walleyes and a 12-pound sheepshead.

All were released.

“I like to catch fish,” Nasby said. “But I don’t eat ’em.”