Dosidicus gigas, the only species in the genus, is the largest and most powerful member of a family of oceanic squids, the ommastrephids. Jumbo squid can reach 50 kg mass and 1 m mantle length (~2.5 m overall length) and are endemic to the eastern Pacific, ranging from southern Chile to Alaska. It is a locally abundant and voracious predator that, despite its muscular physique and formidable beak, consumes mostly vast quantities of small fishes and crustaceans. The squid is also cannibalistic, but the extent of this behavior in nature is not known. A non-scientific introduction to jumbo squid can be found at http://news.nationalgeographic.com/news/2003/07/0718_030718_jumbosquid.html

Dosdidicus gigas in captivity. Photo by L. Roberson.

Perhaps the jumbo squid is most widely known through the numerous mass strandings that have occurred over the last several years in California and the Pacific Northewest, as far north as Sitka, AK (http://news.nationalgeographic.com/news/2005/02/022 3_050223_giantsquid.html). Reasons for these strandings are unknown. Another unknown, which has given rise to much popular controversy, is to what extent Dosidiucs poses a threat to humans. Although they have a reputation for being dangerous, especially to divers, this is more a matter of personal perspective and opinion than fact ( http://www.montereycountyweekly.com/issues /Issue.03-10-2005/cover/Article.cover_story).

Current research in the Gilly lab is focused on the migratory behaviors of Dosidicus in the field, both in the Sea of Cortez and in the Monterey Canyon system off Monterey Bay, CA, and on aspects of its physiology that allow the squid to make numerous excursions into a midwater low-oxygen environment. Studies of migrations rely on a variety of tagging methods -- conventional plastic tags, implanted archival electronic tags and pop-up satellite tags. This work is supported by TOPP, the Tagging of Pacific Predators project. See http://news-service.stanford.edu/news/2007/march14/squid-031407.html and www.newscientist.com/article.ns?id=dn11374

Jumbo squid being landed prior to tagging in the Sea of Cortez . Photo by J. Schulz.

Pop-up satellite tag attached to jumbo squid just prior to release. Photo by W. Gilly.

Respiratory physiology research involves measurements using live, captive squid onboard research vessels in the Sea of Cortez (National Science Foundation support) and off Monterey in collaboration with scientists at Monterey Bay Aquarium Research Institute. Some work is also carried out at the Moss Landing Marine Laboratories, Moss Landing, CA.

Jumbo squid in respirometry flow-tank at Moss Landing Marine Laboratories. Photo by L. Zeidberg

Jumbo squid in the Sea of Cortez are both ecologically important (as predator and prey for sperm whales, bill-fishes, tunas and sharks) and economically critical to many communities. In the area around Santa Rosalia essentially the entire economy is focused on squid fishing. Jumbo squid is now the third largest fishery in Mexico. Our tagging studies have revealed a seasonal migration of jumbo squid between the fishing grounds off Santa Rosalia (summer and fall) and Guaymas (winter and spring). Migrations into and out of the Sea of Cortez are not yet understood.

Squid fishing zones off Santa Rosalia and Guaymas. Seasonal migrations are indicated -- eastward in late fall; westward in late spring. Exact routes are unknown. Map by Ashley Booth

Inside a jumbo squid cleaning and processing plant in Santa Rosalia. Processed squid are exported to Korea.

See other Dosidicus pages:

MBARI films squid

New Volvo semi-rig on the beach for hauling fresh squid from San Bruno (just south of Santa Rosalia) to Mexico City via La Paz and ferry.

An auspicious discovery marked graduate student Danna Shulman's first field season. During her participation in a research cruise in the Sea of Cortez in June 2006, an enormous gelatinous egg mass was found by diving scientists. Bubbling with excitement, they took video, filled sample jars, and handed them over to Danna, whose interest the early life history of squid was well-known. She watched the embryos hatch, delighted by this unprecedented opportunity.

It was generally agreed that this tremendous egg mass (the size of a VW bug) and the tiny hatchlings (smaller than a grain of rice) could only belong to the great Humboldt squid, with which the Gilly lab has become so enamored in recent years, and whose eggs had never been seen before in the wild. A genetic analysis back at the lab confirmed this identity, and Danna's research on the early life history of this species was well on its way.

When incredibly fortuitous egg masses aren't being dropped in her lap, she produces hatchlings in petri dishes, by collecting eggs and sperm from adult squid and performing artificial fertilization. Larger juveniles can be caught off the side of a boat at night, by dip net. As the baby squid grow from hatchling to juvenile, their body shape and muscle structure change dramatically, affecting their swimming and thus their ability to catch prey, evade predators, and disperse throughout the environment. Danna is describing the anatomy and mechanics of this transition (for more on this topic see The Illustrated Guide to Making Squid Babies by Danna Shulman).

Electronic tagging studies have been carried out by the Gilly group as part of the TOPP program since 2001 (See ATTENTION FISHERMAN! poster). Gilly was able to expand the research program in 2005 with funding from the National Science Foundation, Packard Foundation and National Geographic Society. The most surprising finding of this work is the amazing ability of Humboldt squid in the Sea of Cortez to tolerate low oxygen (hypoxic) conditions at hundreds of meters beneath the ocean surface -- depths that have 10% of the oxygen concentration normally found at the surface. The squid do not only tolerate this hypoxia, they remain in this hostile environment all day long and actively feed there. At present we do not know exactly how they accomplish this physiologically. But other predators, including sperm whales, elephant seals, sharks and large tunas probably wish they could duplicate the feat--they all dive to the daytime squid depth but can only remain there for much shorter times.

Although Humboldt squid were abundant off Monterey in the 1930's, they essentially vanished until 1997-98, when they reappeared with El Nino. Since then they have become entrenched in the Monterey submarine canyon, and postdoc Lou Zeidberg published a noteworthy paper on this topic in summer 2007 that was covered by the New York Times. This squid is a major predator that is probably restructuring local and regional ecosystems. Since 2004, Humboldt squid have spread from central California to Glacier Bay, Alaska. Their ecological impacts in these rich waters remain to be investigated.

During the last two years, Zeidberg has also studied the local market squid, Loligo opalescens, discovering that 90% of eggs hatch nocturnally and that infestation of the egg capsules by an annelid worm, Capitella ovincola, actually improves the hatching rate (see Video/Photos). Zeidberg will remain in the lab next year but has accepted a position working with a group from NOAA in La Jolla. They will be examining the population dynamics of the market squid.

Fall 2007