The Farallones Longest Studied White Shark and the Devil's Teeth

The Red Triangle and Our Oldest Local White Shark

Surfers and divers along the central and northern California coastline have long been aware that large great white sharks (white sharks) are observed and encountered most during the fall months. Scientists such as California Academy of Sciences researcher Dr. John McCosker have also documented a significantly larger rate of encounters with humans (>40%) in what is called the Red Triangle during these months. Peaking around October, we call these months of higher observation and encounters with white sharks “Sharktober.” The fall months are also the period when adult white sharks return from the middle of the Pacific to the Farallones and other coastal seal aggregation sites as part of an incredible five thousand mile annual migration.

As early as the 1980s, researchers at the Farallon Islands Dr. Peter Pyle and Scot Anderson recorded large white sharks arrive in late summer, and feeding in spectacular predation events on the pinnipeds that gather to mate and feed. Identifying these sharks via matching photographs of dorsal fins, these scientists were able to identify individuals and document their disappearance each winter, and return the next year. This includes the now famous shark Tom Johnson, first observed in 1987 and tracked across the Pacific and back again.

Migration Patterns of Tagged White Sharks (Source Jorgensen et al. Proc Biol Sci. 2010)

Tom Johnson (TJ) is the longest studied white shark in the world. Numerous photographs and several electronic tags have been used with this shark as technology has developed over the past few decades. A satellite tag on TJ in 2004 was one of the first to show that white shark males regularly migrated to the white shark Cafe in the central north Pacific, between California and Hawai’i. Smaller scale acoustic tags have shown that Tom’s regular hunting grounds are around SE Farallon Island and Tomales Point in Marin County.

Tom Johnson, like many other sharks, is recognizable by his scars and the distinct shape of his dorsal fin. Tom’s length was recorded to be at least 13 feet long, and today measures nearly 17 feet. Since white shark males mature between 10 and 12 feet, long term tracking and observations of Tom have proven that white sharks are very long lived. A study published in the journal Marine and Freshwater Research suggested males take 26 years to reach sexual maturity, whereas females aren’t ready to have babies until they’re about 33 years old, much later than originally estimated. This would make Tom well over 50 years old. That study also showed that white sharks can live over 30 years and possibly as much as 70 years. Tom disappeared for several years and it was feared he might have been lost to fishermen in the open sea, but Tom re-appeared two years ago. Now thats a good reason to celebrate Sharktober!

Visit the Farallones

Join Shark expert David McGuire on a unique exploration into the Greater Farallones National Marine Sanctuary, observing, photographing and recording marine wildlife from seabirds to whales, and maybe even a great white shark!

We lead these unique trips each Sharktober when the white sharks return from their amazing migration of over 4000 miles round trip to forage in our National Marine Sanctuary. As part of NOAA’s National Marine Sanctuary White Shark Stewardship program, we collect data using photographs and observations on whales, seabirds and white sharks while educating the public on the importance of white sharks and all life in the ocean.
These unique natural history trips to the Devil’s Teeth, (the Island of the Great White Shark) focus on the history, geology and biology of the Greater Farallones and San Francisco Bay. We only book in fall when the white sharks return and the weather is clement for our passengers and students. We focus on shark conservation and the health of the entire marine ecosystem in our sanctuary. Although we will watch whales and seabirds, and seek sharks- these trips are conservation and outdoor marine education and are not shark specifically watching of diving trips- but we often see sharks!

Contact for more information.

Note: These trips are not affiliated with the Earth Island Institute.