Some people don’t understand the allure of ice fishing. Others understand it so well that in winter they’re on hard water every chance they get.

Count Chad Schaub and Anthony Rodriguez among the latter. Both from Michigan, they’ve been on Chisago Lake, just north of the Twin Cities, all week.

Previously, also for weeklong fishing jags, Schaub and Rodriguez were on the frozen Mississippi near Alma, Wis.; Hebgen Lake in Montana; and Lake Metigoshe in North Dakota.

Competitive ice fishermen — yes, there is such a thing — Schaub and Rodriguez will be on Chisago Lake on Sunday, vying as they did in Wisconsin, North Dakota and Montana for thousands in cash and other prizes in a North American Ice Fishing Circuit (NAIFC) contest.

As many as 60 two-person teams (team entry fee: $200) will be on the ice when competition begins at 8 a.m. Sunday. Fishing will continue until 1 p.m., with a weigh-in to follow.

On Chisago, teams will be allowed to weigh eight sunfish and eight crappies. The fish must be alive.

Last year, 39 teams competed on Chisago in an NAIFC contest, with a winning weight of 7.42 pounds (also for eight sunfish and eight crappies) earning a top prize of $2,400.

In its eighth year, the NAIFC is the brainchild of Jack Baker of Northfield, Minn.

“My daughter, who’s a freshman in college, started ice fishing when she was 5, and she and I began competitive ice fishing together when she was 6,’’ Baker said. “She just loved to ice fish, and still does.’’

A golf pro in summer, Baker saw a business opportunity in 2008 when the Trap Attack ice-fishing tournament series shut down. He and a partner, Mike McNett of Chicago, jumped in, founding NAIFC with five tournaments over the 2008-09 winter, including one on Chisago.

This winter, seven stops are scheduled, including the national championship Feb. 6-7 on Mille Lacs and nearby Knife Lake.

“Usually we invite the top 10 finishers from each of our tournaments to compete in the championship and hold it in the following December,’’ Baker said. “But this year there was no safe ice in December, so we pushed it back to February.’’

An ice-fishing evangelist, Baker uses the NAIFC contests to spread the gospel of hard-water angling. This weekend, for instance, in addition to the Sunday competition, events designed to attract more people to ice fishing will be held in Chisago City and nearby Center City.

Friday night, at Frankie’s Live Bait and Marine in Chisago, a 5-7 p.m. ice-fishing seminar open to the public will be offered during which experts will discuss and demonstrate various winter angling techniques, including jigging and hook and bait selection.

Saturday, from noon to 1 p.m. at the Center City Fire Hall, a “Kids Ice Fishing Camp’’ will be held, followed from 1-3 p.m. by an opportunity for kids and their parents to apply what they learned on the ice, fishing.

Equipment is provided, and kids who attend will be given free ice-fishing rods.

As many as 400 people have attended previous NAIFC seminars and clinics.

On Sunday, competing anglers will be limited to Chisago Lake, the channel between Chisago and South Lindstrom Lake, and South Lindstrom Lake.

Entrants will line up for the 8 a.m. start in the order in which they registered for the contest. Snowmobile and four-wheeler travel is allowed, as is walking.

“But we don’t have a shotgun start,’’ Baker said. “In fact, no passing is allowed. Competitors must move onto the lake in the order they’re lined up.’’

Minnesota law allows individual anglers to keep 10 crappies and 20 sunfish (or bluegills or hybrids). Theoretically, Baker said, it’s possible anglers will keep more than the eight crappies and eight sunnies that they will weigh.

“But almost no one does that,’’ he said. “These guys already know what the average size of these fish is in Chisago, and they want to beat that. They’re not going to keep smaller fish while they travel around the lake. Either way, they have to have the fish they’re going to weigh separated from any other fish when they return to the starting area by the deadline, 1 p.m.’’

Despite the intense interest in competitive ice fishing among some traveling anglers, including the NAIFC-leading Michigan pair, Schaub and Rodriguez — who by Sunday will have pre-fished Chisago for a week — the biggest cash prizes for individual contests usually go to locals, Baker said.

“Oftentimes they know the lake best,’’ he said. “I know on Chisago, everyone will be looking for the hybrid sunnies that swim in that lake, some of which can grow to 10 inches. Those are winning fish.’’

Weigh-in following the contest’s 1 p.m. close will be at Frankie’s. Legendary ice guru Dave Genz will officiate.

More information, and online entry forms, are at www.naifc.com.