5 possible reasons for the increased shark activity in Southern California

Many people in Southern California (and Orange County specifically) have sharks on the brain at the moment. Between the devastating attack on a swimmer this past weekend that has left a woman fighting for her life, to multiple sightings up and down the Orange County coast that has caused numerous beach closures, people are buzzing about it all.

And yes, there was also another shark attack last Memorial Day in Corona Del Mar. And while it certainly seems like there are more sightings, keep in mind that technology is a factor in this as well — everyone now has an iPhone or a drone and there’s rarely a sighting that goes undocumented nowadays.

But why this increase in shark activity in Southern California recently?

We spoke to Christopher G. Lowe, Ph.D., Professor of Marine Biology at California State University Long Beach and Director of the Cal State Long Beach Shark Lab to find out some possibilities for all of this.

Below, Lowe outlines five possible reasons for the recent influx in shark activity around Orange County:

1. Increased white shark population

“Shark populations are increasing [in Southern California] because we’ve done a better job at protecting white sharks.

“They have been protected in California for 20 years now. Protecting them from being killed in commercial fisheries has allowed the population to recover.”

2. Increased marine mammal populations

The population can’t recover this well without having food. Marine mammals were on the verge of extinction in the Pacific by the early 1900s — they weren’t protected until the 1970s. Since then, marine mammal populations have recovered better than anyone could want.

“That has allowed the adult white shark food source to come back.”

3. Southern California is a white shark nursery

“Southern California is a nursery for white sharks, a place where females come and give birth to their young. We think they do that because it’s a safe place for them, it’s a good place for them to learn how to feed and the water is warm closer to shore.

“The young white sharks are very temperature sensitive. When the water is warm, they like those conditions. When the water is cold, like in our normal winters, they don’t like it and typically leave. When they get a little larger, they’re less susceptible to cold water.

“But it’s pretty rare to have adult white sharks along our beaches. We just don’t see big white sharks off our beaches. We see big juveniles, and a big juvenile can be up to 12 feet long — but that’s still a juvenile.

“The big juveniles are from three to five years old. Males mature from 7 to 9 years old and females mature around 12 years old. Which is when they’re over 10 or 12 feet, and that’s the age group we know the least about.”

4. Weather patterns like El Nino

“Conditions like El Nino change the migration pattern of these sharks. During that recent El Nino winter, none of the babies that were born at Southern California beaches (that would normally leave during the winter) left.

“It made it look like suddenly there were more sharks that came from nowhere. Sharks born the previous year just didn’t leave and then the next spring new sharks came in, so it made it look like we had way more sharks than normal.”

5. Rising sea temperatures

“When it comes to global climate change and ocean temperature rise, scientists want to make predictions based on the distribution of species. White sharks can keep their bodies warmer than the water they swim through, they can be found as far north as the gulf of Alaska and as far south as the equator.

“They have this ability that other shark species don’t. The problem is, as global temperatures and ocean temperatures rise, white sharks might get pushed to areas where they don't normally occur in high numbers.”

Also keep in mind

“Two things for the public to keep in mind: First, we now have all these great science tools that we can use to answer these questions. The problem is is that there is no funding for this work. For the first time we have the tools to answer the questions, there’s just no money to do the research.

“Second, we really need people to maintain a perspective. They have to remember that while shark attacks occasionally occur, they’re still unbelievably rare.

“When you think about how many millions of people use Southern California beaches every year, we have so few incidents. It’s really something we have to keep in perspective.”

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