When You See A Shark Off SoCal's Coast... Who Ya Gonna Call?

They're big, they're burly -- and they're baaaaack.

We're talking about basking sharks, the second largest fish in the world, and they've been spotted all over the coast of Southern California for the first time in decades.

Scientists with the National Oceanic and Atmospheric Administration are reporting dozens of basking shark sightings from Ventura and the Santa Barbara Channel, all the way to Los Angeles and the Channel Islands.

Basking sharks can grow up to 30 feet long -- almost the size of your average Metro bus -- and boast a mouth that can stretch open to more than 3 feet wide. (Lucky for us they eat plankton, not people.)

While they're found pretty much all over the world, especially off the coasts ofIreland and Scotland, basking sharks are a fairly rare sight in Southern California.

In the 1950s and '60s, boaters and fishermen reportedly spotted them in the hundreds or thousands, They've since all but disappeared -- until now..

"It's a pretty big deal," said NOAA fisheries biologist Heidi Dewar, who is part of the team that's now keeping a close eye on the sharks. "Time will tell if this is a one-off rebound or a real comeback."

No one is quite sure why basking sharks seemed to disappear, but Dewar said there's strong evidence that, locally, many of them became victims of commercial fishing bycatch. They were also targeted eradication efforts against populations of basking sharks in British Columbia to keep them out of salmon fishing nets.

Fortunately for the sharks, things have changed quite a bit since then. In 1994, California banned gill and trammel net fishing within three nautical miles of the state's coastline, and that zone appears to make up a good portion of the sharks' preferred feeding grounds.

A basking shark spotted by NOAA researchers near Santa Cruz Island (Pike Spector/NOAA)

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Dr. Chris Lowe with the Shark Lab at Cal State Long Beach agreed that the latest sightings appear to be a good sign, but noted that it could also just be another indicator of climate change.

Warming ocean temperatures and recent marine heatwaves are causing plankton and other microorganisms to slowly shift north up the West Coast, bringing the larger animals that feed on them (e.g.: basking sharks) with them.

"Ultimately, what we don't know is why they show up at certain places at certain times," Lowe said.

That knowledge gap is largely due to the fact that scientists simply haven't had the opportunity to properly study their range in the Pacific or what their regular offshore habitats look like. And because it's been so long since one of them was spotted, data collection on basking sharks in California has been sporadic and inconsistent over the years.

"It was, honestly, off my radar that we used to have basking sharks off California," Dewar said.

NOAA researchers follow a basking shark for satellite tagging off Santa Cruz Island (Pike Spector/NOAA)

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But with more basking sharks popping up in recent weeks, NOAA is now actively maintaining a database of those sightings -- and they're asking anyone who sees one to let them know.

"We can take that data and link it to environmental conditions that day and try to get a better sense of what their preferred habitat is or even get a boat out on the water to catch up with them and put a satellite tag on them," Dewar said.

So if you do spot a basking shark, help a scientist out and call NOAA's basking shark hotline at (858) 334-2884 or send an email to basking.shark@noaa.gov.