Friday, April 09, 2010

"Humboldt Squid... Thriving-Thanks to Ocean Dead Zones"

From Scientific American:

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.

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.

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