A shark preying on a seal at the Alcatraz Island dock was witnessed by a group of tourists and park officials Saturday. At around noon tourists waiting for the ferry witnessed a large pool of blood at the surface. What appears to be a 8-10 foot great white shark consumed the carcass at the surface within feet of the dock much to the excitement of young onlookers. A National Parks staff member confirmed the event by email.
“This is the first recorded predation event by a white shark I’m aware of in the San Francisco Bay,’ said David McGuire, Director of the San Francisco based shark conservation group Shark Stewards and Research Associate at the California Academy of Sciences. “It is definitely a white shark, about 8-10 feet, based on the video sent to us. The tourists were very excited.”
Although there is no known record of an attack on humans by a white shark inside the bay, great white sharks have been observed inside the Bay on several occasions. A study by theStanford Tagging of Pacific Predators documented several tagged sharks entering and exting the Bay in a study published in the Proceedings of the Royal Society in 2009.
New video released by the Alcatraz Ferry to Kron 4 shows a shark breaching as it strikes the pinniped. Although likely a California Sea lion (Zalophus californianus), it is possibly a harbor seal (Phoca vitulina).
Five white sharks were recorded entering the Bay over a period of two years in a study published by the Stanford Tagging of Peacfic Predators program; one shark entering and exiting four times in one year. The only documented white shark fatality in San Francisco came on May 7, 1959, when Albert Kogler Jr., 18, died while swimming in less than 15 feet of water after he was attacked off Baker Beach, about one mile west of the Golden Gate Bridge.
“For me its pretty exciting and a sign that the health is returning to the San Francisco Bay ecosystem. We swim in the Bay every day at the Dolphin Club without a shark encounter. Its why we call this month Sharktober.” said McGuire. “The risk of shark attack is extremely low. Over eighty swimmers from the Dolphin Club and South End Rowing Club swam from Alactraz last week, and another race is scheduled for next weekend. It is up to the leadership what to do, but I suspect this shark is well fed and long gone.”
The Dolphin club- SERC traiathlon starting with 60 swimmers from Alactraz was a success and without any views of sharks. Story on SFGATE below. Shark Steward’s David McGuire helped lead offf the test swim on Friday, entering very near to the location of the predation event the week below. Our swimmers also swam unscathed
Shark Stewards has an observation program called Shark Watch and observations can be recorded in the citizen science data base. The public is encouraged to report any white sharks to public safety officials and can alert on twitter with the hastag #SharkWatch.
Practices on how to avoid a white shark attack are on the Shark Stewards web site at sharkstewards.org.