Southern California has been invaded by hordes of Humboldt squid in recent days, a bizarre onslaught for a deep-sea creature that normally keeps a low profile. The invasion began last week in San Diego, according to GrindTV and the Los Angeles Times, and has since spread as far north as Santa Barbara, with "perhaps millions" swarming offshore and hundreds reportedly washing onto beaches.


The Humboldt squid — aka "jumbo squid," but not to be confused with giant squid — also invaded California in 2007, when some as large as 20 to 40 pounds washed ashore, and they showed up again last year. This year's invasion isn't quite as jumbo as those, the Ventura County Star reports, with most of the squid ranging from 5 to 10 pounds, but it's surreal nonetheless.


And while surfers and beach-goers marvel at all the red, alien bodies littering the coast, fisherman have been reeling in live ones by the thousands.


"They're kind of everywhere, from the shore to the islands and anywhere in between," Hilal Helweh of Channel Islands Sportfishing tells the Star. "I don't know how far north they're going to go," adds Mike Thompson of Ventura Sportsfishing. "It seems like there's a steady stream of them, not one school."


Humboldt squid live in the Eastern Pacific at depths of 660 to 2,300 feet, according to the Smithsonian National Zoo, and normally gravitate south of the equator — they're named after the Humboldt Current, located in their historic habitat off South America's west coast. Recently, though, they've been venturing farther and farther into the Northern Hemisphere, periodically swarming around California and even as far north as Sitka, Alaska. This, according to the Smithsonian Zoo, is "raising alarm about ecological problems possibly underlying the northward migration."


What kind of ecological problems? Scientists aren't sure, because Humboldt squid are so elusive and mysterious that little is known about their biology or behavior. Their eggs have never been observed in the wild, for example, and we don't even have an estimate of their global population size. But because the northerly invasions are so unusual for these reclusive creatures, many experts believe some kind of environmental change has triggered the behavior. From the Smithsonian:


"Some oceanographers suggest that warming oceans are at fault, while others speculate that declining numbers of the squid's predators due to overfishing may have allowed Humboldts to expand their range."

Scientists have also floated the possibility that these migrations are spurred by El Niño-related shifts in ocean currents, and may even represent "an attempt at permanent colonization," GrindTV notes. What is clear is that the squid make themselves at home while vacationing up north, feasting on a wide array of native fish — many of which are likely inexperienced in evading jumbo squid. Humboldts grow up to 6 feet long and can gain 100 pounds in a year, requiring voracious appetites that experts worry will cause long-term damage to West Coast fisheries. 


Still, many fishermen don't seem to mind the occasional invasion for now, as long as they can catch palatable squid in place of lost fish. One angler tells the Ventura County Star this year's swarm makes for better eating than in '07. "The better thing is the taste," says Helweh of Channel Islands Sportfishing. "[In 2007], they were so big they tasted horrible. They were not table fare. These taste a lot better."


The Humboldts can vanish as suddenly as they appear, however, so anyone hoping to capitalize on this year's invasion better hurry. According to the Redondo Beach Patch outlet, the squid have already disappeared from around Long Beach. "Thousands, maybe millions here one day and then gone the next," says skipper Andy Siratt of Long Beach Marina Sportfishing.


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Russell McLendon ( @russmclendon ) writes about humans and other wildlife.

Squid row: Jumbo squid invade California (again)
'Jumbo' Humboldt squid are swarming off the California coast, creating a tentacled spectacle from San Diego to Santa Barbara.