CORPULENT CALAMARI: Changes in the eastern Pacific Ocean make many researchers think the Humboldt's range will continue to expand. But the jumbo squid's ecological impact has yet to be determined. Image: SCOT ANDERSON
Although many of the Pacific Ocean's big species are floundering, one large creature of the deep seems to be flourishing. The Humboldt squid (Dosidicus gigas, also known as jumbo squid, owing to its sizable nature) has been steadily expanding its population and range: whereas sightings north of San Diego were rare 10 years ago, the squid are now found as far north as Alaska.
Many researchers attribute the squid's recent success to the very climate, current and oxygen-level changes that have been hurting populations of other species in the diverse California Current.
"I find their adaptability and their perfection in dealing with anything nature throws at them to be a remarkable feature," says William Gilly, a professor of biology at Stanford University whose lab has spearheaded much of the U.S. work on Humboldt squid. "They're able to explore and take advantage of new environments that are compromised in any way." And they can move quickly, says John Field, a fisheries biologist with the National Oceanic and Atmospheric Administration's Southwest Fisheries Center, adding: "They're capable of very large migration patterns." Gilly's group recorded one squid that was tagged in Monterey, Calif., and last detected around Mexico 17 days later.
Humboldt squid are formidable predators, reaching about two meters in length and 50 kilograms, dwarfing the 30-centimeter-long California market squid (Loligo opalescens) that often end up as calamari. (Despite their outsize nickname, however, jumbo squid are not the largest cephalopod in the seas—that honor goes to the colossal squid, Mesonychoteuthis hamiltoni, rare specimens of which have measured more than five times the size of most Humboldt squid.) But their impressive size is just one of the things about these squid that keep divers, fishers and scientists fascinated.
Despite their often-unnerving abundance recently in coastal waters and commercial fisheries alike, little is known about the lives of these prodigious creatures of the deep.
Although these large squid are thought to live for only a year or two, they emerge from an egg measuring about one millimeter long. To sustain such rapid growth they appear to have nearly endless appetites.
Hungry, hungry Humboldts
A growing mass of these hungry squid could have a large impact on some fish stocks, especially those that are already faltering.
"They can eat pretty much all they want," Gilly says, noting that researchers have found a range of meals inside the squid, ranging from tiny krill to 40-centimeter-long hake—and even some salmon remains. Humboldts have even been known to eat each other.
As evidence for their impact on U.S. fisheries continues to trickle in, their effect off in Chile, where the squid have been prevalent for much longer than most parts off the U.S. coast, has been more conspicuous: "There's very strong evidence that the squid expansion had a huge impact on the hake fisheries," says Field, who helped organize a symposium on the animal in 2007. "It looks like they're doing the same migration as hake, which concerns me."
The squid are making it harder to measure some fish populations, such as the hake. Humboldt are often found in and around hake schools and have a very similar sound signature as the fish, Field explains. So researchers who survey hake populations with hydroacoustics, which uses sound waves to detect and measure marine life, often get unusable data.
The squids' presence is also being felt in terrestrial food webs. With expanding ranges, there has been increasing interest in these squid among sportfishers of the U.S. west coast, and commercial fisheries for the squid are growing in Mexico, Chile and Peru. But humans are not the only land lovers that have begun sampling these squid. Both bears and wolves have been observed dining on Humboldt, likely from carcasses that have washed ashore, an occurrence that is only likely to increase with growing squid populations.
Continued research will help scientists understand more about what these squid are eating—and what's eating them—as well as where they are spending the majority of their time. "There's a lot of squid out there, and there's no reason they wouldn't be having an impact" on local ecosystems and food webs, Field says. And especially if the squids' range continues to expand, he adds: "I wouldn't rule out the potential for a huge impact."