Shark sightings: How officials decide which ones are credible

Sharks are regularly sighted in the waters off San Luis Obispo County, particularly during the summer and fall. Three credible shark sightings were reported on three consecutive days in September, but none have been reported so far in October.

Whenever a report is made, a Cal Fire battalion chief runs though a list of more than 20 questions: Did you see a fin? How big was it? How far was the shark from the beach?

The answers are meant to determine whether a sighting is reliable enough to justify posting warning signs on local beaches. Most reports are not deemed to be credible.

Although a variety of agencies, including harbor patrol and municipalities, can post shark warning signs, many are posted by Cal Fire. Battalion Chief Phil Veneris in Los Osos is one of three coastal battalion chiefs who evaluate the credibility of shark sightings.

“We try to determine the environmental conditions at the time of the sighting as well as how experienced the person is with the ocean,” Veneris said. “It’s a very high standard.”

“A lot of times, we can make a determination if it is credible fairly quickly,” Veneris said.

If a sighting is deemed to be credible, authorities will post signs for three days warning the public of the sighting and further warning that people entering the water do so at their own risk.

Beaches are closed only in the event of a confirmed shark attack.

Shark experts note that despite the frequency of sightings, attacks are uncommon. Efforts by local authorities to warn beachgoers of the danger posed by sharks increased following a fatal shark attack in Avila Beach in 2003.

Although the warning signs are almost always used for shark sightings, they could also be used in the case of an aggressive sea lion, elephant seal or other dangerous marine animal. However, they are not used for non-life-threatening marine animals such as stingrays and jellyfish.

The procedures for determining the credibility of a sighting are spelled out in a 90-page policy manual that can be found online at www.calfireslo.org. They are based on procedures used in other shark-prone areas such as Hawaii and Australia.

“We are trying to be consistent,” Veneris said.