Great white shark activity — including attacks on sea otters — has increased noticeably in recent months in San Luis Obispo County waters, according to state wildlife authorities.
The activity comes in the form of increased credible sightings as well as an unusually large number of attacks on otters, said Mike Harris, a state sea otter scientist working out of Morro Bay.
“I’ve certainly heard of more credible sightings than in years past,” he said. “That’s anecdotal evidence that there are more sharks present.”
Because little is known about white sharks, biologists are unsure what’s causing the increased activity. One thing is for sure — sea otters are paying the price, particularly in the Morro Bay and Pismo Beach areas.
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Scientists collected 19 injured or dead shark-bitten otters in August and seven already in September. The 10-year average for August is seven and six for September.
This is odd because sharks don’t typically feed on otters, Harris said. They start out their lives eating fish and then transition to seals and sea lions, which have a lot of blubber, making them a more nutritious meal.
“This would explain why the majority of the otters collected have a single bite mark,” Harris said. “These bites are more investigative — like a taste test.”
There have also been credible reports on various websites that track shark incidents. At one site, www.sharkresearchcommittee.com, the public can read summaries of shark incidents from around the state.
The availability of small waterproof cameras allows kayakers and others to take pictures of sharks, which helps biologists determine whether they are white sharks, Harris said. For example, video of a white shark shot by a paddle boarder off San Onofre recently went viral.
Biologists offer several theories why there is so much shark activity in the Pismo Beach and Estero Bay areas. For one thing, they often congregate here at this time of year to feed on the profusion of seals and sea lions.
Unusually cool ocean temperatures this summer may also play a role. This could create mild conditions particularly attractive to sharks.
“Without much data on the white shark population off California, we can only speculate as to the cause for the increase in the otter bites,” Harris said. “But perhaps there are more juvenile sharks in the area, testing various prey items as they transition.”
The state Department of Fish and Game does not have an estimate of how many white sharks live in California waters. Only limited research has been done to study the DNA of sharks and identify individual sharks using unique characteristics.
Anyone who enters the ocean runs the risk of an encounter with a white shark. Experts say the only way to reduce the risk is to avoid areas where sea lions, harbor seals and elephant seals congregate.
Deborah Franzman of Nipomo was killed by a great white while she was swimming near a group of sea lions off Avila Beach on Aug. 19, 2003.
According to state statistics, there have been 95 white shark attacks in California since 1950 with 11 of them fatal. The rate of attacks has not risen over time even though record numbers of people are engaging in marine activities, such as surfing, swimming, kayaking and diving.
More information about white sharks can be found at www.dfg.ca.gov/marine/pdfs/sharkfacts.pdf.