A large patch of oil that crept into the Mississippi Sound, the fertile waters between the state’s barrier islands and its mainland, was a sobering reminder that luck here could run out.

So far, Mississippi has been relatively spared by the massive leak in the Gulf of Mexico when compared to neighboring states. Mississippi hasn’t been inundated with thick oil like some marshes in Louisiana or beaches on the Florida Panhandle.

Oil creeping inside the barrier islands in recent days was a wake-up call for coastal residents such as Darlene Kimball, owner of Kimball’s Seafood on the docks in Pass Christian.

“I kept praying and praying that we’d be protected because we’ve been so fortunate,” she said. “All I can do now is pray, pray, pray.”

Crews cleaned up the large patch of oil found floating Wednesday near Dog Keys Pass, said Cortnee Ferguson, spokeswoman for the joint information center in Mobile, Ala., jointly run by BP PLC and the Coast Guard. Other workers were dispatched to clean tar balls off the beaches of East Ship and Petit Bois islands.

Ferguson described the oil found in the Mississippi Sound as “a mat of floating tar balls.”

State officials, however, called it a large mousse-like slick, with one patch a mile long.

It was not immediately clear how much oil washed ashore on the islands.

Though the spill has mostly missed mainland Mississippi, it has hammered the tourism and shrimping industries here. Some shrimping areas are open, but many shrimpers have gone to work fighting the oil for BP, leaving fewer to trawl.

Kimball’s business is down to practically nothing. She used to bring in thousands of pounds of shrimp and oysters every week during the season but now makes do buying the little shrimp she can get or buying frozen shrimp and paying more for it.

“My livelihood is based on product coming in, and with no product, I have no livelihood. I don’t know what I’ll do,” she said.

In nearby Gulfport, dozens of workers walked the beaches on Thursday scouring the sand for any signs of tar balls or oily debris.

The latest oil sightings create a “heightened concern” that Mississippi may eventually see heavier oil come ashore, but workers remain diligent in trying to spot it far offshore and clean it up out there, said Lauren Thompson, spokeswoman for the Mississippi Department of Marine Resources.

The state is still seeking commercial fishermen with boats bigger that are 50-feet long and capable of fighting the oil farther south in the Gulf, she said.

Still, Gov. Haley Barbour’s office said things could be worse.

“We’ve been lucky that we haven’t seen more, but we’d hoped to see less,” said Dan Turner, Barbour’s spokesman.

“We’ve known that the oil is out there and we are continuing to actively purse an offensive and defensive strategy to get as much of it up as far out as we can,” Turner said. “The idea was to get as much of it as we cold south of the barrier islands and to try to keep it out of the passes.”