There’s a sweet spot in North Idaho waters and it has to do with temperature.

When spring water temperatures hit the 50-degree mark, warm water fish start to become active.

That means bass, crappie and other panfish will chase what anglers toss at them.

“Once the water hits 50 degrees everything starts to move,” Brandon Kron at Black Sheep Sporting Goods said.

The 50-degree mark is so sweet that open water fishers have traded the winter doldrums for a fast-tip rod and roof top boat.

In North Idaho’s many smaller lakes, climbing water temperatures have prompted bass to feed heavily as they enter the prespawn or spawning period.

“Within the next two weeks most small lakes will spawn,” Blake Becker said.

During the prespawn, bass eat a lot to prepare for the time after the spawn, when they guard their beds and quit feeding, which can be a week or two at a stretch.

Once water temperatures hit the mid-50s, male and female bass roam the shallows and clear circular areas in the lake bottom — called beds or nests — where females lay eggs.

In large bodies of water like Lake Coeur d’Alene the temperature might vary from one end to the other, so all bass do not all spawn at the same time.

“I feel like Coeur d’Alene almost has three spawns in one lake,” said Becker, who owns Becker’s Tackle Shop. “In Coeur d’Alene some fish have already spawned.”

Bass in the lake’s southern end, and in its shallow bays, spawn earlier than at the lake’s northern reaches.

Water temperatures in Lake Pend Oreille last week were in the mid- to upper-40s, Becker said.

Regardless of where or when, smallmouth bass will spawn earlier than their largemouth cousins, usually on gravelly or rocky bottom when water temperatures range between 56 degrees to the mid-60s. Their beds can be found at depths of 2 to 20 feet. Bigmouths prefer temperatures warmer than 60 degrees and spawn on soft bottoms in shallow, weedy areas.

“Anywhere that looks like a swamp,” Kron said.

Site fishing is easier for largemouths because their circular beds fanned into a lake’s mud or sand are in shallower water at depths of a foot to 6 feet. But with a little experience and a good vantage point — usually from a boat ­— anglers can spot the gravel nests of smallmouth bass in deeper water.

Because nests are aggressively defended by male fish, they are a good target for anglers. Spring bass techniques often include using soft worms or crawfish fished near the bed to excite and agitate the males.

“They are protecting the beds, so if you throw anything near it, they will go for it,” Kron said.

Soft plastics, jigs, and other bottom baits are effective. Drop shooting a worm or crawfish to keep the bait near the bed works well too.

Despite their aggression, bass may not hit a bait with force. Sometimes they will simply push or move a nearby bait away from the bed.

“They will pick it up and move it,” Kron said. “It may not be in their mouth.”

More often, though, a bass on a bed will strike a lure.

“They will probably attack it,” he said.

As daytime atmospheric temperatures push into the 80s this weekend as predicted, the warming will spread to North Idaho’s 40-plus navigable lakes and the spawn will be in full swing.

“It’s all going to happen shortly,” Becker said. “It’ll be worm and flip-flop weather.”