Castillo clicks a new chart up onto the computer screen, this one showing a map of the Pacific coast of North America and pinpointing where great whites have been caught and how much they weighed. "We have a strong concentration of white shark catches around San Diego and another around San Francisco. We can clearly see two groups. We have very large sizes north of Point Conception and smaller sizes in the south."
Sea lion and seal populations are increasing in local waters, Castillo concedes, but he says they aren't near levels needed to support a population of adult great white sharks. Other factors make the San Diego-Ensenada stretch of the Pacific an unlikely destination for large white sharks, he adds. "You have to remember that these animals are very fragile in biological terms. Contamination and pollution affect them. We have a high volume of navigational traffic in Southern California and all of Baja. This is a disturbing activity for these animals."
All that data notwithstanding, a great white whopper did show up in a tuna net in local waters. Castillo believes it was an anomaly, not a portend of shark-infested waters to come. "That shark was over five meters," he adds. "That is a very rare size, no matter what region we're talking about."