It Must Be Something in the Water : Ventura: Two tourists say they were bitten at the beach. One believes it was a shark, lifeguards suspect a sea lion, but no one is quite sure.

Lifeguards knew something attacked two swimmers in the surf at San Buenaventura State Beach last weekend.

One victim thought it might have been a shark. The other was certain it was a sea lion.

Exactly what it was, however, remained as murky Thursday as a Ventura fog bank.

For a time Thursday morning, lifeguard supervisor Kirk Sturm thought animal-control workers had the culprit. Rangers patrolling Ventura’s beaches reported finding an ailing sea lion at Harbor Cove near Ventura Harbor.

Initially, Sturm--a strong doubter of the shark-attack theory--said flatly that he thought the sick sea lion was probably the mystery beach biter.

Sick or injured sea lions have been known to make unprovoked attacks on swimmers, he ventured.

But just as it was starting to look like it was safe to go back into the water, efforts to capture the sea lion were abandoned and the mammal was allowed to waddle back into the ocean.

About that time, Sturm changed his mind.

“We don’t know exactly which sea lion was doing the biting,” he admitted.

Does that mean swimmers now need to be on the lookout for a deranged sea lion wreaking Jaws-like havoc along Ventura’s beaches?

No, said Sturm.

“We’re not considering anything to be unsafe yet,” he said. “We are monitoring the situation and if anything changes, we will take action to protect the safety of swimmers.”

What remained clear Thursday was that two tourists swimming at San Buenaventura beach near Seaward Avenue on Sunday afternoon required medical treatment after being bitten by something in the water.

The first attack occurred about noon, when a 21-year-old man stepped into the water and immediately felt something bite him. The Lancaster resident, whose name was not available, suffered a laceration on his foot, Sturm said.

“It was really gushing blood,” said Erica Tomaschow, a waitress at the Eric Ericsson’s fish house nearby. “He said it was a shark.”

But Sturm disputed that possibility.

“The marks weren’t indicative of a shark bite,” Sturm said. “They were more like scrapes.”

The second attack, about two hours later, occurred in about the same location, Sturm said. Peter Dewees, a San Francisco educator, said he was bodysurfing when he saw a dark, sinuous shape coming toward him.

The animal clamped down on his knee and swam away when he pushed it, Dewees said. And that’s when he saw it.

“A wave came in and I saw a perfectly silhouetted sea lion in its crest. I could see fins and a snout,” Dewees said.

Dewees required 35 stitches to repair the damage to his knee, he said. But he is not bitter--his Ventura escapade even brought him a little notoriety. San Francisco Chronicle columnist Herb Caen mentioned it in his column.

If the attack was mounted by a sea lion, it is very unusual behavior, said Burney Le Boeuf, an expert in marine mammals at UC Santa Cruz. He noted that California sea lions live in colonies on the Channel Islands and that July is breeding season.

A sea lion may become aggressive if it thinks someone is threatening its mate, he said.

“If they’re going to be rambunctious, it’s right now, especially if someone gets too close,” Le Boeuf said.

Although Dewees seemed certain about what he saw, officials said they will never know for sure what bit the men. And whether it was the same animal.

And whether it is still out there.