Visitors to Black’s Beach got quite a pungent surprise on Sept. 17 and 18. Hundreds of giant Humboldt squid (Dosidicus gigas) washed up on shore Saturday night and Sunday morning, greeting beachgoers with a rather fishy smell. The phenomenon, however, is not an isolated incident. The squid, it seems, have been making large group appearances more and more frequently in recent years, said some regular La Jolla-area beachgoers.

“People are seeing them more regularly now, which is perhaps a reflection of the fact that we have resident populations [of squid] here now,” said Nigella Hillgarth, executive director of Birch Aquarium. “The squid have seasonal migrations [from south to north], but there may be more going on to cause these events.”

Hillgarth said she and other experts aren’t sure what is causing the beachings, but one hypothesis is that the squid may have chased prey too close to shore and couldn’t get back out into the open ocean.

In 2009, dozens of Humboldt squid washed up on shore, possibly the result of a 4.0-magnitude earthquake offshore.

Hillgarth said there was no indication the event was the result of contamination in the water from the recent sewage spill caused by the regional blackout on Sept. 8. There were, however, other potential causes to be considered.

“We can’t rule out that they could have died due to eating some algal bloom or toxin in the water,” she said. “Really, [the species] is still quite a mystery. There’s still a lot of research going on.”

— Kendra Hartmann