Two weeks ago a satellite tag from a great white shark washed ashore onto Angel Island inside the San Francisco Bay. The tag was from a nine foot male shark tagged a year ago by Stanford's Tagging of Pacific Predators (TOPP) and has been verified as one of theirs. Was the shark inside the Bay? Skeptics claim the tide could have brought the tag in. This could be true but it still means the shark was close enough for the shark to enter the front of the Bay for the tag to wash in. In fact, TOPP's data has shown that tagged white sharks have entered the bay and exited. One shark returned two years in a row.
Historically white sharks have very likely frequented the deeper waters of the San Francisco Bay, yet with few human encounters. The front of the bay is host to larger fish, pinnipeds, harbor porpoises and sharks like sevengills and sixgill sharks. It is plausible that a hungry white shark might follow one of their prey into the Bay and have a scan around before leaving.
The only white shark attack in the bay occurred in 1959 outside the Golden Gate to a man swimming off Baker Beach.
Should swimmers be concerned about sharks in the Bay? I think it is the opposite. Sharks should be worried about humans.
Last week I and a few friends swam without wetsuits from the beach at the Dolphin Club in Aquatic Park San Francisco around Alcatraz Island and back over 3.5 miles to raise awareness for shark conservation. This second annual event is intended to alert the public that sharks are here in the Bay, and that sharks are important and potentially at risk. We departed in the pre-dawn in 56 degree waters. The building ebb created a roadblock for the swimmers behind and a few of us struggled to get past a 2 knot current before heading back to the beach.We swam tight to the rock, past decrepit warning signs, the aging prison building and crumbling guard towers from a vantage that few ever have.
As the strengthening ebb dragged me towards the Gate I had to swim in an easterly direction. Head down in the water I had two hours to contemplate. I thought about all the men and women who have swam unmolested by sharks over the past centuries. I thought about the many species of sharks, sixgill sharks, sevengills, soupfins, spiny dogfish that swim unseen in the cool green waters. I thought about the myth of Alcatraz, the shark infested waters, and that the greatest risk to the prisoners was really hypothermia and not the sharks.
I thought about Lou Marcelli and his recent passing, and what he thought when he swam in the Bay. Lou was the "Commodore " of the Dolphin Club, a swimmer, a fisherman and a truly iconic character. Loved by all who knew him, I thought how he would be swimming in the Bay one last time when his ashes are to be scattered.
I also recalled the humorous insights Lou shared when we interviewed him in our documentary Swim for Sharks, we produced last year. Lou and other dolphin clubbers account sea lion bites, ships, pelicans and even angry grebes as the real threats to swimmers, not the sharks.
We completed the swim after 3 hours in the water- over twice last year's swim. We swam because sharks are in trouble worldwide. An estimated 100 million sharks are being killed each year, and several species are endangered. Sharks are important for the health and balance of marine ecosystems, including the Bay. For ocean health and the health of fish populations humans rely on to survive, we need sharks. That is why I will keep swimming, and fighting for sharks- white sharks in the Bay or not.
This weekend November 3rd, we are heading out on our Farallon Islands marine science and wildlife expedition to see whales, seabirds and discuss sharks. Please join us!
Follow the adventure on the shark adventure blog.
We have a matching grant to support our Programs- You can still sponsor a swimmer!
David McGuire, MEH
Director, Shark Stewards.org