Professional shark photographer Greg Amptman and San Diego diver Michael Bear encountered 3 large Sevengill sharks (Notorynchus cepedianus) off the coast of La Jolla this week. One was a large male, about 7 ft long, the second, a more medium sized-shark and the third, which came right up to Amptman's camera port, before abruptly turning away when the flash went off, was also large: 7-8 ft.
Sevengill sharks are not unknown here in San Diego, their presence having been noted by local divers since about 2007 or so. They begin appearing around April of each year and stay local for about 6 months before disappearing again until the following April-May. It is not known where they go or even the reason they linger in the area, although it is speculated that they may be coming into shallower waters to mate, due to the large numbers of females that have been seen and photographed with mating bite marks on them. There has also been some evidence that, wherever they go for the winter exposes them to bites from the Cookie Cutter Shark (Isistius brasiliensis), which is a benthic, or deep-dwelling shark.
They are now seen quite commonly by divers in certain parts of La Jolla.
Bear runs a local citizen science project, now under the auspices of a local non-profit group called Ocean Sanctuaries, which will attempt to identify which individual Sevengills are returning from year to year by subjecting high definition photographs of them taken by local divers to a pattern recognition algorithm to establish a basline study for future researchers.
See here for more information: http://sevengillsharksightings.org/our-methodology-introduction/
Sevengill sharks are not normally aggressive towards divers, unless they are pulling strings of bloody fish behind them. Worldwide, there have been fewer than a dozen attacks since the 17th century. They are in the Cowshark family and are identified by their unique freckling pattern of black marks on the dorsal and later sides.
For more information on Sevengill sharks, see below: