They have spent close to 20 years studying the elusive ocean predators from Santa Cruz, up to Tomales Point in Marin County, all the way to the Farallon Islands.
Various environmental actions to protect the creatures appear to be working.
"It's real indicative that the ecosystems we have here are healthy," Oregon State University Professor Taylor Chapple said. "It's healthy enough to support, they're healthy enough to support this population of, this stable population of really big large apex predators."
Each shark has a unique dorsal fin which makes them easier to track.
Scientists say the population increase does not mean we will see more attacks.