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| Earth on Sep 25, 2011

Humboldt squid washing up on southern California beaches

High tides brought hundreds of Humboldt squid onto beaches along southern California last week. No one knows for sure why.

It must have been a surreal sight for kristoforc, seeing hundreds of beached Humboldt squid along the shoreline, some still flapping helplessly at the water’s edge. In a video that he posted on September 19, 2011, on YouTube, the synopsis read:

I was walking with my roommate on the beach in San Diego and suddenly a small wave washed up hundreds of squid. No one seems to know why this happened. Some of the onlookers tried throwing them back in the water, but they kept washing back up.

Humboldt squid, once thought to inhabit east Pacific tropical and subtropical waters, have been expanding their northward and southward ranges in the past decade. As a result, they’ve become common in waters off southern California, and incidences of squid washed ashore, which used to be rare, have increased since about 2003.

These enigmatic creatures live at depths of 660 to 2,300 feet (200 to 700 meters), coming close to the surface at night to feed. Like many other squid species, they’re believed to be relatively short-lived – perhaps one to two years – and are thought to die en masse after spawning. During their lifetime, Humboldt squid eat voraciously and grow at a fast rate. They’ve been known to reach lengths of 6 feet and weigh in at 100 lbs, though the specimens that beached along southern California coastlines during the week of September 17, 2011, were typically about 1 to 2 feet in length.

That week, along the southern California coastline, dead-squid-on-the-beach stories were reported in local newspapers and made for dramatic local TV news. Meanwhile, many local beach communities wasted no time clearing carcasses off the beach to beat the unpleasant odor that comes with lingering dead squid on hot beaches.

But at Little Corona and China Cove beaches, which are protected areas, there would be no dead squid pick-ups. Michelle Claud-Clemente, marine protection and education supervisor for the City of Newport Beach parks department, was quoted in a September 23, 2011 article in Corona Del Mar Today:

Yesterday we had a bit of a squid die-off. From the number of fish found with the squid, I think the squid were feeding and got caught up in the surf …. This is a normal event and we did not/will not remove [the carcasses]. High tide tonight … should take care of a lot of the carnage.

Laura Detweiler, City of Newport Beach recreation and senior services director, also told Corona Del Mar Today:

This happens from time to time as squid spawn or feed to close to the shoreline. High tide washed these guys in this morning and won’t wash them away until this evening when high tide hits again at 6:49 p.m.. We cannot remove them as this is a protected area. We need Mother Nature to take her course.

At the time of the squid beachings, fishermen were reporting larger than usual squid catches, as shown in this short video clip posted by Dana Point Fishing and Whale Watching.

KCBS, a Los Angeles CBS affliate, featured a story, on September 23, about Newport Beach fishermen returning from what had been very successful fishing expeditions. One 40-person expedition returned with a staggering 990 Humboldt squid. Dan Phillips, a fisherman, spoke about the experience to KCBS correspondent Michele Gile:

It’s hard work. They fight hard. You’ve got to remember, you’re working a mechanically, manually-worked reel … and they’re jet-propelled.

These are intriguing news stories. But what’s the back story on the squid invasion?

In the past decade, the northern hemisphere’s Humboldt squid range has been expanding northward. Off the southern California coast, they’ve been a boon to recreational fisheries, especially when the squid congregate in enormous numbers close to shore, as was apparent on the week of September 17, 2011. But it has hurt the commercial hake fishery because hake is one of the prey taken by Humboldt squid. And as the squid expand their range southward along the coast of South America, they could also inflict similar damage on the hake fishery in those regions.

Humboldt squid have been found as far north as waters off Sitka, Alaska. They washed up on beaches along the Oregon coast in October 2008, and, as seen in the video clip below, on British Columbia beaches in August 2009.

Scientists investigating the expanding Humboldt squid range have proposed several explanations. It’s possible that the squid have benefited from the steep declines in large fish species, like tuna and billfish, that prey on juvenile squid. Or perhaps their range expansion could be tied to El Nino events, which periodically bring warm waters northward. Some researchers are studying the expansion of low oxygen zones — dead zones — in the eastern Pacific, caused by a variety of climatic and environmental factors. These dead zones are inhospitable to fish but Humboldt squid have adapted to survive in low oxygen waters. As a result, expanding dead zones have become new habitat for Humboldt squid. (These dead zones, in most cases, are found in deep water. At night, Humboldt squid move to the oxygen-rich waters near the surface to hunt for food.)

In the past decade, the increasing northward range of Humboldt squid has made these creatures common off the coast of southern California. Sometimes, large numbers of squid congregate close to shore, perhaps to feed or spawn. Some of them get washed onto beaches during high tide, causing the stranding spectacles seen during the week of September 17, 2011. It’s a phenomenon that’s likely to reoccur. Still, it’s unlikely that anyone could ever get used to the sight of these large bizarre-looking creatures washed up on beaches.

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