September 7, 2003

Discussing Santa Cruz shark
bait with a local guru

Sentinel surf columnist Ben Marcus talks with Santa Cruz shark guru Sean van Sommeran of the Pelagic Shark Research Foundation:

SANTA CRUZ SENTINEL: It's September. A woman was killed by a white shark at Avila Beach. There were persistent sightings of a white shark off San Onofre State Beach in Southern California. Does your research explain why there was a big white shark cruising off San Onofre last week?

SVS: Well, as I have said, from our research it appears that there is a migration of juvenile and sub-adult sharks that arrive along the California coast in late spring and early summer. As the season progresses into late summer and fall we see the arrival of the larger adult white sharks, like the one photographed recently off San Onofre. They hit the coastal areas in late summer and fall, and these arrivals continue into December. But by January and February, these same sharks are moving offshore into deeper water. This seasonal abundance appears most closely associated with the shoreward migration of the elephant seals.

SCS: Any action up here yet?

SVS: A couple of reports of sightings from Manresa and up the coast. Supposedly two guys got brushed by sharks at Scott's Creek and Waddell Creek, and a bodyboarder reported seeing an otter being attacked at Manresa. All possible. All believable.

SCS: What do you do at your foundation?

SVS: The PSRF is involved in research on the behavior of white sharks. We have been doing this since 1992 and have established the shark research study at AF1o Nuevo Island north of Santa Cruz. Part of this research involves tagging and tracking sharks at AF1o Nuevo with satellite transmitters that record a shark's global position, depth and water temperature every two hours. The tags record for months then pop off at predetermined times, come to the surface and upload that data to satellites.

SCS: Interesting stuff?

SVS: Very. Until recently it was thought white sharks were pretty much coast-huggers and not ocean-crossers. From our observations at AF1o Nuevo Island we saw great whites with swordfish harpoons stuck in them, and sharks wrapped up in long-lining gear and swordfish nets. That kind of fishing is all open-water and that is one of the reasons we arrived at that theory early on.

During the late 1980s, just before we were founded and white sharks were protected, they were openly hunted up and down the California coast, but specifically at the Farallones Islands near San Francisco by local fishermen who would sell the jaws. In 1990 there were two shark attacks a month apart at Davenport Landing, and then we had a problem with trophy fishermen targeting them. We tagged white sharks and blue sharks and came up with some fascinating data. One blue shark turned up less than 600 miles off the coast of Japan, which makes that the longest recorded transit by any shark. Most of the white sharks we tagged swam deep into the Central Pacific, and by that I mean they dove deeper than 500 meters. One of our sharks made it to Guadalupe Island off northern Baja, and one shark tagged by the Farallones guys made it all the way to the Hawaiian Islands and cruised Kahoolawe for several months.

SCS: I don't care how big and bad you are or how well you swim. How do you find Hawaii in the middle of all that?

SvS: Well, there has been a lot of research done on the sensors in the noses of white sharks and it turns out they are not just sensitive to vibration and electrical fields, but also magnetic currents and minute temperature differences. Who knows, they may even have a flow meter in there. The research was ground-breaking and not only academically interesting but crucial to management and conservation.

For example, the Monterey Bay Aquarium and everyone else has not had much success keeping a white shark or even a blue shark in captivity, and we think we know why. Many of these pelagic, open-ocean sharks spent a good part of the year swimming at great depths as much as several hundred meters, and that could be an important part of their physiology. They may need that time at that depth to survive, thermo regulate or whatever. Even a million-gallon tank is not going to satisfy that need, and that may be why white sharks will never make it in captivity.

Got a surf story? Contact Ben Marcus at TheBenM@aol.com.