Chas Champagne’s best day of scouting for Lake Pontchartrain speckled trout in recent years was actually accomplished in his car.

The owner of the Matrix Shad line of baits and avid angler had just returned from a Florida vacation three Octobers ago when he had some business-related phone calls to make.

Rather than sitting in a stodgy office, he decided to multi-task and drive around his neighborhood in Eden Isles and next door in Lakeshore Estates. It was at the latter destination that he came across something that really caught his eye.

“At the back lagoon across from the Convention Center, I could see this super-hard grass line from my car,” Champagne recounted. “I was like, ‘Man, that’s got to be good.’ A light, little cold front had come through, and it was slick-calm on that back shoreline.

“I got home, and Kristie and I took the boat out. We went back there. I was using a jig, but you could have caught them on a stick bait. That grass line was like a wall that was about 10 feet off the bank, and it just canyoned down,” Champagne said. “It was a perfectly straight line all the way down (the shoreline). I would just cast right up to the edge of it, and let it free-fall. It was every cast down that whole shoreline. I fished that lagoon every other day for three weeks.”

The grass hasn’t grown as well along that shoreline in any year since, but Champagne spends his autumn days hunting for similar situations, and generally has no trouble finding them. But, without question, the autumn bite has changed dramatically in eastern Lake Pontchartrain in the past half-decade, and locating grass beds is now essential to success.

“The lake’s obviously gotten fresher,” Champagne said. “It used to be when you got into September, the L&N (train bridge) and the Highway 90 bridge over the Rigolets would really get awesome, and it would be those really big fish.”

That annual run peaked in September 1999, when Jason Troullier caught the third-largest speckled trout — an 11.24-pounder — ever brought to scales in the Bayou State.

“It’s not like that was a fluke fish,” Champagne said. “Every August, September and October, that was the thing to do — fish structure and deep water in the Rigolets, and catch really big fish.

“But I personally think that breed of fish really isn’t around this time of year anymore. The 14-inchers can’t live in that environment. In that deep water, they’ll get eaten by something bigger than them.”

So Champagne doesn’t try to force the issue. He’s adjusted by perfecting his grass-mat pattern. Most of the time, it’s accomplished by throwing jerk baits (also called stick baits and twitch baits) to the edges of grass beds close to relatively deep water.

“The fish are hanging 4-to-5 feet down in water that’s 8-to-10 feet deep,” he said. “The Matrix Minnow, when you throw it, it’s a really slow-sinking bait, so you can fish it down to 8 or 10 feet. The grass line might be right up tight to the bank, whether you’re in Geohagen (Canal), Lakeshore Estates or Eden Isles. You don’t want to do it along a 2- to 3-foot-deep shoreline. If I did that in Lake Catherine, I’d be dragging grass the whole time.

“The fish are suspended,” he said, “but they’re using the edge of that grass to ambush the bait that comes out of it.”

In the fall, grass beds tend to hold white shrimp migrating through the estuary to spawn outside in the big bays and sounds. The speckled trout know relating to grass is essential to filling their bellies and adding fat reserves for the winter.

Champagne said he throws the jerk baits right up to the edge of the grass, and he uses a particular cadence to attract the most bites.

“It’s like a walk-the-dog thing — twitch-twitch-pause, twitch-twitch-pause,” he said. “I’m not saying if you cast and reel it wouldn’t work. But I fish it like I’m walking the dog underwater.

“The pause is really important, I think. I can’t tell you how many times I’m relaxing the bait, just sitting there for a second, and all my slack gets straightened out,” Champagne said. “They love clobbering that thing when it’s not moving. It’s fun. You don’t need to catch more than 5 or 10 fish to enjoy it.”

Although the jerk bait fish won’t rival the one Troullier’s 1999 giant, they are still nice-sized trout, Champagne said.

“You fish a jig or a popping cork, and they’re all 12-inchers, but you switch to that jerkbait, and all of a sudden, they’re magically 16-to-18 inchers,” he said.

Champagne’s favorite colors are something he calls “nightmare,” which has a black back with a clear belly and “pink lemonade,” which has a green back with a pink belly.

To locate areas to throw them, Champagne relies on quality eye wear.

“The No. 1 most important thing is to make sure you’ve got polarized sunglasses on,” he advised. “You can’t see those hard grass lines without them, and that’s really important.”

Especially if you happen to be scouting from your car.

Follow Amy Wold on Twitter, @awold10.