Humboldt squid

Humboldt squid are generally found in the warm Pacific waters off the Mexican coast; studies published in the early 2000s indicated an increase in northern migration. The large 1997–1998 El Niño event triggered the first sightings of Humboldt squid in Monterey Bay. Then, during the minor El Niño event of 2002, they returned to Monterey Bay in higher numbers and have been seen there year-round since then. Similar trends have been shown off the coasts of Washington, Oregon, and even Alaska, although no year-round Humboldt squid populations are in these locations. This change in migration is suggested to be due to warming waters during El Niño events, but other factors, such as a decrease in upper trophic level predators that would compete with the squid for food, could be impacting the migration shift, as well.[9][26]

A 2017 Chinese study found that D. gigas is affected by El Niño events in the waters off Peru. The squid populations cluster into groups less, and are thus more dispersed, during El Niño events. Additionally, during warm El Niño conditions and high water temperature the waters off Peru were less favourable for D. gigas.[27]

The Humboldt squid's diet consists mainly of small fish, crustaceans, cephalopods, and copepods. The squid uses its barbed tentacle suckers to grab its prey and slices and tears the victim's flesh with its beak and radula. They often approach prey quickly with all 10 appendages extended forward in a cone-like shape. Upon reaching striking distance, they open their eight swimming and grasping arms, and extend two long tentacles covered in sharp hooks, grabbing their prey and pulling it back toward a parrot-like beak, which can easily cause serious lacerations to human flesh. These two longer tentacles can reach full length, grab prey, and retract so fast that almost the entire event happens in one frame of a normal-speed video camera. Each of the squid's suckers is ringed with sharp teeth, and the beak can tear flesh, although they are believed to lack the jaw strength to crack heavy bone.[19]

Their behavior while feeding often includes cannibalism and they have been seen to readily attack injured or vulnerable squid in their shoal. A quarter of squid stomachs analyzed contained remains of other squid.[28] This behavior may account for a large proportion of their rapid growth.[19][29] An investigation of the stomach contents of over 2,000 squid caught outside of the Exclusive Economic Zone off the coasts of Chile found that cannibalism was likely the most important source of food. Over half of the squids had the beaks of D. gigas in their stomachs, and D. gigas was the most common prey item. The researchers do note, however, that squids which were jigged in the light field around the survey vessel showed much more cannibalism.[17]

Until recently, claims of cooperative or coordinated hunting in D. gigas were considered unconfirmed and without scientific merit.[30] However, research conducted between 2007 and 2011 indicates this species does engage in cooperative hunting.[31]

The squid are known for their speed at eating; they feast on hooked fish, stripping them to the bone before fishermen can reel them in.[19]

Female squids lay gelatinous egg masses that are almost entirely transparent and float freely in the water column. The size of the egg mass correlates with the size of the female that laid it; large females can lay egg masses up to 3–4 m in diameter,[32] while smaller females lay egg masses about one meter in diameter. Records of egg masses are extremely sparse because they are rarely encountered by humans, but from the few masses found to date, the egg masses seem to contain anywhere from 5,000 to 4.1 million eggs, depending on size.[33]

Squid as taken at Port Otway, western Patagonia, 1888

A 24-kilogram (52 lb) specimen caught off the southern Californian coast displays deep-red chromatophoric coloring.

Commercially, this species has been caught to serve the European market (mainly Spain, Italy, France, and Ireland), Russia, China, Japan, Southeast Asia, and increasingly North and South American markets.

It is the most popular squid in the world, as of 2019 a third of all squid hunted is this species.[34]

The method used by both artisanal fishermen as well as more industrial operations to catch the squid is known as jigging.[11][17] Squid jigging is a relatively novel method of fishing in the Americas.[35] It is done by handlining by artisanal fishermen, or by using mechanical jiggers.[11][36] Jigging involves constantly jerking the line up and down to simulate prey, a reel with an elliptical or oval-shaped hub helps with this.[36][37] Squid jigging is done at night, using bright overhead lights from the fishing boats which reflect brightly off the jigs and plankton in the seawater, luring the squid toward the surface to feed. Squids seem to like to strike at the jigs from adjacent shadowed areas, especially the shade under the hull of the boat.[35][36] Often as many as 8 to 12 jigs are on snoods on one handline, and many more are used on automated squid jigging systems.[36] The lines are hung anywhere from 10 to 100m in depth, depending on the power of the lamps used.[36][37]

The jigs are called poteras in Spanish. Different types of jigs are suitable for either handlining or for mechanical jigging for jumbo squid. They are made from bakelite and/or stainless steel, and measure 75 to 480mm in length. Jigs can have a single axis, or one to three 'arms' (ejes) which wave around when the jig is jerked,[11] and a series of crowns (coronas) of bristle-like wire-hooks, the hooks lacking barbs, making up the tail.[11][36] The body of the jigs is usually phosphorescent,[11] but glow-in-the-dark lures may be attached to them.[37] Jigs are extremely selective, not only can one type of jig attract only squid, often the jigs can select for a single species of squid, and even specific sizes of that species. The more arms and crowns, the more hooks, the higher the chances of snagging and actually reeling in the squid.[11]

Since the 1990s, the most important areas for landings of Humboldt squid are Chile, Mexico, and Peru (122–297, 53–66, and 291–435 thousand tonnes, respectively, in the period 2005–2007).[17]

Based on 2009 national fisheries data, in Mexico this species represents 95% of the total recorded catch of squid. 88% of this is caught off the coasts of Sonora and Baja California Sur.[10]

Squid steaks, uncooked, in the USA

Because the flesh of the animals is saturated with ammonium chloride (salmiak), which keeps them neutrally buoyant in seawater, the animal tastes unpleasantly salty, sour, and bitter when fresh. To make the squid more palatable for the frozen squid market, freshly caught Humboldt squid are commercially processed by first mechanically tenderizing them, dropping them in icy water with 1% mixture of lactic and citric acid for three hours, then washed, then soaked in another vat with a 6% brine solution for three hours. There is also a method for home cooks to neutralize the unpleasant taste.[12]

Compared to other types of seafood, Humboldt squid is inexpensive in Pacific South America, retailing around US$0.30/kg in Peru, and about US$2.00/kg in Chile, in the early 2010s.[12][13]

In Chile the squid is eaten in chupes and paila marina.[12] In Peru, the practice of making ceviche from cheap squid began in the poorer parts of Lima when the meat became available in the 1990s, and has since spread to Cuzco. It is sold on the street in food carts, as well as cevicherias, restaurants dedicated to this cuisine.[13] In the United States it is made into 'squid steaks'.

Numerous accounts have the squid attacking fishermen and divers.[38] Their coloring and aggressive reputation have earned them the nickname diablos rojos (red devils) from fishermen off the coast of Mexico, as they flash red and white when struggling on a line.[14]

Although Humboldt squid have a reputation of being aggressive toward humans, some disagreement exists on this subject. Research suggests these squid are aggressive only while feeding; at other times, they are quite passive.[28] Some scientists claim the only reports of aggression toward humans have occurred when reflective diving gear or flashing lights have been present as a provocation. Roger Uzun, a veteran scuba diver and amateur underwater videographer who swam with a swarm of the animals for about 20 minutes, said they seemed to be more curious than aggressive.[39] In circumstances where these animals are not feeding or being hunted, they exhibit curious and intelligent behavior.[40]

Recent footage of shoals of these animals demonstrates a tendency to meet unfamiliar objects aggressively. Having risen to depths of 130–200 m (430–660 ft) below the surface to feed (up from their typical 700 m (2,300 ft) diving depth, beyond the range of human diving), they have attacked deep-sea cameras and rendered them inoperable. Humboldt squid have also been observed engaging in swarm behavior when met by the lights of submersibles, suggesting that they may follow or are attracted to light. Reports of recreational scuba divers being attacked by Humboldt squid have been confirmed.[41][42]

In Chile, at the end of the 50s and early 60s, electrophysiological and neurophysiological studies were carried out by the Montemar Institute of Marine Biology,[43][44][45][46][47] in Valaparaiso, Chile. The remarkable size of the squid giant axon and squid giant synapse possessed by the Humboldt squid made it ideal for manipulative work in the laboratory.[43] This research was chronicled in the documentary Montemar y Los Laberintos de la Memoria [Montemar and The Labyrinths of Memory]. 2016.