SOLANA BEACH, Calif. -- With no sightings of a shark that killed a retired veterinarian off Solana Beach, San Diego-area beaches were reopened Monday morning.

David Martin, 66, was swimming with friends about 7:30 a.m. Friday, training for a triathlon, when he was killed by an apparent great white shark about 150 yards from shore in Fletcher Cove, near where he had lived for 38 years.

Following the attack, shark warning signs were posted along the eight miles of beaches between La Jolla and Carlsbad, and lifeguards advised people to stay out of the water along 17 miles of San Diego County coastline.

The Encinintas Surf Festival just north of Solana Beach was canceled, but surfers and others were not ordered out of the water amid near-record heat.

Helicopter crews scanned the shallows along the beaches over the weekend, but no shark sightings were reported and officials planned to lift the warnings Monday.

"This shark is probably long, long gone by now, but this is all precautionary," said Capt. Craig Miller, Marine Safety Officer for the city of Solana Beach.

Sunday, Martin's family returned to the scene of his death to grieve but also celebrate his life.

"He died doing what he liked, surrounded by his friends, in a place he loved," said son Jeff Martin. "Even through our grief, this gives us an inner peace."

He said the shark attack shocked most everyone.

"People would ask us about sharks and we just kind of laughed -- we're Solana beach, it doesn't happen here," he said.

When asked, he said the shark would not scare him out of the water.

"I went surfing yesterday, does that help?" he said. "I'm taking my boys out tomorrow."

Martin was training for a triathlon in a group of eight swimmers, all in wetsuits, when he was attacked from below, thrust into the air, then dragged under.

White sharks feed primarily on seals and sea lions, and experts said the shark may have mistaken the swimmers for a pod of seals.

Shark attacks are rare in the San Diego area. In 1994, a woman's body was found with shark bites along Ocean Beach in San Diego. Before that the most recent fatal shark attack in the county was in June 1959 when a free diver was killed.

But some used the shark attack to press their argument that a protected area for seals -- Children's Pool in La Jolla -- should become a beach for people, instead, although it is 10 miles away from Solana Beach.

"Seals have a place on the California coast. I just think it's very important that place isn't within a few feet of the largest open water swimming areas in San Diego," Mitch Thrower, co-owner of Triathlete Magazine, told CBS News.

On Aug. 19, 2003, at Avila Beach in San Luis Obispo County, a woman who regularly swam among sea lions there was fatally attack by what was believed to have been a great white.

The most recent fatal shark attack in California was Aug. 15, 2004, when an abalone diver was attacked in Mendocino County.

White sharks, which generally prefer water colder than that along the Southern California coast, are known to give birth in warmer waters.

Encinitas Lifeguard Lt. Paul Chapman told the San Diego Union-Tribune a baby white shark was found at a nearby lagoon about two weeks ago.

Volker Hoehne, president of the San Diego Free Divers, told the newspaper that members of the club also reported seeing two great whites under water off Oceanside last week.

With near-record high temperatures throughout the area, San Diego's main beaches were packed over the weekend, with most people taking advantage of the cool water as usual.

Lt. Nick Lerma of the San Diego Lifeguard Service said that even though many people were talking about the shark attack, he saw little change in the behavior of beachgoers.