Their largest competitor just unveiled a $150 million expansion, which might make some casino managers want to fold.

But the Isle Casino & Racing in Pompano Beach has tried a different approach: They doubled down.

Something must be working. The casino’s slot revenues — their main income source — are up about 10 percent year-over-year since Feb. 2, the day rival Seminole Casino Coconut Creek added more slots, restaurants and other features. And the quarterly reports show a $48 million net income, tops among the chain of 15 Isle casinos in the United States.

“I think it’s a great example of getting prepared for the competition, in capital investment and improved customer experience,” CFO Dale Black said at a quarterly earnings conference call last week.

Adds Chad Beynon, vice president and senior analyst for Gaming/Leisure at Macquarie Capital, “I’m shocked they’ve been able to be as strong as it’s been. It’s one of the better returns on investments in the regional markets.”

The Seminole Casino Coconut Creek, one of seven operated by the Seminole Tribe of Florida, can offer blackjack, pay what comes out to be a 12 percent tax (compared with 35 percent on slots for the Isle) and allows smoking. Many gamblers prefer to light up, but the Florida Clean Indoor Air Act applies to casinos overseen by the state.

Although the tribe doesn’t release its figures, Coconut Creek took out an ad in May claiming “No Other Casino Stacks Up.” The gist of it: The tribal casino outpaces the Isle by more than 3-to-2 in slot action. And the Isle is the leader among the six South Florida pari-mutuels with slots, doing twice the business of competitors Mardi Gras Casino and Gulfstream Park Racing & Casino in Hallandale Beach.

The Isle has spun its non-smoking disadvantage into a positive, billing itself as a “non-smoking casino” and hoping to pluck the clean-air players. They also upgraded the buffet, improved the guest service program and devoted more money to slot promotions, handing out $6.4 million the past four months compared with $4.2 million over the same period last year.

The casino averaged more than $11 million in monthly slot revenues since Coconut Creek’s expansion, compared with more than $10 million for the same period.

“We worked to reintroduce the Isle to the market, so early on in the fiscal year we incurred some extra cost; now we’re seeing the benefit,” Black said.

Gregory Roselli, an analyst for UBS Securities, said, “At the end of the day, it’s a different enough product vs. Coconut Creek, which is big, smoky and has a Vegas feel. It might not appeal to the same crowd you’d find at the Isle.”

Roselli said players who go to a casino several times a week “might prefer a place where they know everybody and they’re better served.”

“The reason it works is because the Florida market is so deep,” he said. “There’s more than enough people to support both properties. As the Isle continues to grow its business, there’s enough room for them to grow its share without going toe-to-toe with Coconut Creek.”