San Pedro Workshop to Study Local Spider Crab Population


Bring your soft-soled shoes, warm clothing--hip waders if you have them--and become a marine naturalist for a day. No experience necessary.

The Cabrillo Marine Museum in San Pedro is inviting people over the age of 13 to take part Saturday in an ongoing research program on the spider crab population at the Point Fermin Marine Life Refuge near the museum.

In a “Science at the Seashore” workshop from 12:30 to 3:30 p.m., people will be shown how to measure crabs, determine their sex and record data. They’ll then spend two hours observing and counting spider crabs at the tide pools.

“This is a way for the public to get some experience doing a research project,” said museum curator Cathy Crouch, who will conduct the workshop. “They get a better understanding of why we do research, how we do it and what we do with the data.”


The crabs, which have legs up to a foot long, are found hidden in surf grass at the extremities of the tide pools. “They are uncovered at the lowest low tides,” she said. “You have to really look for them.”

The research program began in 1986 when almost 300 of the crabs were counted in one day in the tidal area. “The museum was interested in what they were doing there and developed a monitoring program to check on when they occur,” she said.

The original number has never been equaled, with subsequent counts turning up no more than 70 crabs. Crouch said researchers haven’t determined why the numbers fluctuate, but it could be because of reproduction patterns or migration. “They could be out there, but somewhere else,” she said, adding that monitoring will continue at least five more years.

The workshop costs $5, and reservations may be made by calling 548-7563. Another spider crab workshop will be given Jan. 27 from noon to 3 p.m. The museum is at 3720 Stephen White Drive.