Squid Run – Invasion of the Cephalopods

New Year’s Eve, and the clock was just about to strike midnight. In the streets and bars of San Diego’s famed La Jolla district, bands were blaring, bodies were gyrating and the party-goers were feeling no pain. But the terrestrial celebrations were rather tame compared to the orgies and feasts taking place in the waters immediately off the beach at La Jolla Shores, roughly a mile away. Literally millions of squid had invaded the La Jolla Submarine Canyon. With them had come a host of hungry predators and scavengers intent upon feeding on the squid.

Photo Op

For an underwater photographer and filmmaker, it is difficult to ask for a better opportunity to film animal behavior and natural history. As a rule, wildlife photographers, especially those of us who work underwater, are constantly racking our brains trying to figure out ways to get close to animals in order to film them well. But with the squid, the dilemma was that there were so many, I was finding it almost impossible to frame up a good shot. I couldn’t even clear my mask or grab my regulator without simultaneously grabbing a handful of rubbery squid. There were squid around our heads, between the second stage of our regulators and chins, under our armpits, between our legs and under our fins. My assistant, Mark Thurlow, later told me that he felt like we were diving in a swimming pool three-quarters of the way full of some kind of jiggling pasta.

Wild Scene

Groups of squid were mating everywhere we looked, and squid egg casings already obscured the sand bottom. Furthermore, a variety of fishes and other animals including bat rays, thornback rays, sheep crabs and sea lions were feeding on the squid. Talk about a wild scene.

Of course, there were scenes like the one we were witnessing all over Southern California that night, as the La Jolla Submarine Canyon is only one of any number of sites where market squid gather to mate during typical Southern California winters. Also known as common squid, these cephalopods usually inhabit deep water, but they mate and lay their eggs in much shallower surroundings. The mating and egg laying typically occur over sandy bottoms, sometimes at depths as shallow as 30 to 40 feet/9 to 12 m, but more commonly in slightly deeper, cooler water. The event is often referred to as a “run,” and during heavy runs, which can last for several weeks or even months, literally millions of squid gather to mate in coastal canyons and along steep sand drop-offs at the offshore Channel Islands.

The instinct to mate among market squid is incredibly strong, and the males appear frantic as they attempt to embrace a female. Market squid are only believed to live for one year, just long enough to reach sexual maturity, mate and die. It is quite common to see three, four or more males all clutching the same female in an undersea orgy.

Squid are capable of swimming forward, backward and sideways with near equal rapidity, jet-propelling themselves with a directable siphon and undulating tail fins as they seek out a mate. When mating, squid often change colors rapidly as they pulsate from creamy white to deep purple to brown and green. The color changes are believed to express excitement and communicate with other squid. Often when a male is successful in his efforts to grab onto a female, his tentacles instantly blush a scarlet warning to deter other males from attempting to woo his mate. In an effort to ensure that he perpetuates his own genetic code, a mating male quickly and adeptly passes a packet of sperm underneath the mantle of the female. Soon afterwards she will use the sperm to fertilize her eggs.

After mating, the females plant a single egg casing in the sand. The whitish 8- to 12-inch-/21- to 31-cm-long egg casing contains approximately 200 eggs. It is estimated that only a few will live long enough to reproduce. While each female plants a single egg casing, the sheer number of egg casings transforms the once-brown bottom into a shag carpet of egg casings. Five to seven days after an egg casing is planted, you can see the bright-red eyes of the unhatched embryonic squid inside. In another week or so the eggs will hatch, and the newborns will instinctively head for deep water. One year later, those that manage to survive will take part in the mating ritual.

Shortly after mating, the captivating color shows slow and cease as the adult squid weaken, taking on a sickly, pallid hue. Their sucker-lined tentacles soon become grossly disfigured, and their bodies show signs of marked deterioration. With their life cycle complete after only a year, death is not far away.

The Morning After

Within a time span of a few hours to a few days after heightened mating activity, the sea floor becomes covered with piles of dead and dying squid. The squids’ weakened state makes them easy prey for a wide variety of scavengers and predators who are quick to take advantage of the opportunity to gorge themselves. Often bat rays, horn sharks and angel sharks devour so many squid that they end up immobilized on the sea floor with pieces of partially eaten squid dangling from their mouths. It is a scene reminiscent of the need to get to the closest couch after a Thanksgiving Day feast when you are stuffed full of turkey and stuffing.

As a general rule, bat rays are somewhat wary of divers, but during squid runs it is not uncommon for these rays to swim, rest and feed within touching distance of divers.

Rockfish, black seabass, cabezon, sculpin and myriad other fishes often join the fray. Lobster and crabs leave the protective confines of nearby reefs to forage out in the open on the dead and dying adult squid.

High up in the water column sea lions, harbor seals, pilot whales and blue sharks prey upon the concentrations of still-living adult squid. Blue sharks rarely come so close to shore, but the presence of so much easy-to-catch food is sometimes too much to resist. On the surface, flocks of sea gulls, pelicans and other seabirds gather to feed. The great concentrations of seabirds, sea lions, seals and occasional pilot whales at the surface are a sure sign of the activity below.

Even with so many hungry mouths to feed, the squid often die off in such huge numbers that in places they become stacked one on top of the other in piles that are 2 feet/.6 m thick. Interestingly, the seemingly vulnerable egg cases are not heavily preyed upon. Some specialists suspect that this is due to the presence of proteins that prove repulsive to potential predators. However, once they hatch, newborn squid become fair game for a wide variety of predators.

Hatchling squid are sought after by a variety of crustaceans, fishes, seabirds and marine mammals. In fact, life is so difficult for squid, specialists estimate that from the average egg casing, which contains approximately 200 squid eggs, only a half-dozen or fewer will survive for one year, when they will attempt to mate before they, too, perish.

Many of the species that prey upon the squid, such as blue sharks and pilot whales, are highly migratory, so there is little question that common squid play a vital role in marine ecosystems in many oceans, in addition to local waters in Southern California.

Because of the importance of the squid, some specialists are very concerned about what appears to be declining numbers in market squid. Common squid are commercially fished as a food source and for biological studies due to their highly developed optic nerves, which makes them ideal for research and teaching. In recent years the take has been alarmingly low in many areas that had been very productive in the not-too-distant past. It is difficult to say with absolute certainty whether the reduced catch is part of a natural cycle, a result of the recent El Niño or due to overfishing. Fisheries specialists will be keeping a close eye on the matter during upcoming seasons.

Diving the Squid Run

When the squid do mate at depths that are safely accessible to sport divers, it is generally during the middle of winter. However, I have witnessed a heavy run in August in San Diego during the mid-1970s. Whenever a run occurs, it is a wonderful time to dive as long as conditions allow. The squid are driven by strong instincts as they search for willing partners, and they pay little attention to outsiders, whether potential predators or underwater photographers, so getting close is not a problem.

Sometimes the activity is hot and heavy during the day, but as a rule it is much more intense at night. If you do have the opportunity to night dive with the squid, it is wise to become familiar with the dive site during daylight. As a rule, there are far more squid around at night, and dive lights often prove to be squid magnets. At times I have been surrounded by so many squid that I could not see my fins, gauges or dive buddy. The concentration quickly dissipated when I turned my light off or covered the beam for a moment, but it can be rather disorienting to be surrounded by a dense cloud of swirling squid. That feeling is heightened considerably if a sea lion or bat ray — or occasionally, a small shark — suddenly pokes its head into view. Make sure you are mentally prepared for such close encounters.

In addition, in many places such as San Diego’s La Jolla Canyon and in a variety of sites at the Channel Islands where divers enjoy the squid runs, the bottom is a bit deep and drops away quickly, so be sure to monitor your depth gauge. As with any night dive, it is wise to do what you can to make sure you know the area well before making a night dive with the squid.

Story and photos by Marty Snyderman